Why I don’t take vitamin D supplements

Vitamin D has been associated with numerous health benefits, including cardiovascular and immune health, bone strength, and prevention of cancer. However, studies claim that most of us are deficient in vitamin D, and thereby unnecessarily vulnerable to increased heart disease, stroke, cancer, diabetes, osteoporosis, infection and autoimmune disorders. According to a review of recent studies in Natural News, there is a woldwide epidemic of vitamin D deficiency:  59% of the population is “vitamin D deficient”.  The article goes onto to speculate that “What’s becoming increasingly clear from all the new research is that vitamin D deficiency may be the common denominator behind our most devastating modern degenerative diseases.”

Supplementation with vitamin D capsules is advocated even by “primal” advocate  Mark Sisson, normally one to take inspiration from our paleolithic ancestors, shunning medication and embracing a lifestyle of eating whole foods and engaging in moderately stressful, playful exercise:

We can’t all bask in the midday sun.. For those of us unable to run shirtless and shoeless through a sun kissed meadow…our option is oral intake… food will help, but it won’t suffice. You need something stronger. ..take a good D3 supplement if you can’t get real sunlight. As long as you don’t go overboard on the dosage, you’re good to go. If it’s not in an oil-based capsule, just take it with a bit of fatty food (not a stretch for an Primal eater). It travels the same pathway and results in the same benefits. It’s always easier to just let nature take its course, but it’s not always realistic. A good general rule is 4000 IU per day.

Therefore, we should supplement with vitamin D.  Right?

Not so fast.  A closer examination shows that low vitamin D levels may be a consequence, not a cause, of poor health.  And that supplementation with Vitamin D may actually be counterproductive.  Let me explain.

Homeostatic regulation.  First, I’d like to return briefly to a previous post I wrote.  In The case against antioxidants, I presented evidence that supplementation with antioxidants is not only unhelpful, but may actually be counterproductive.  In my article, I surveyed several meta-analyses of  the antioxidant vitamins A, C, and E — demonstrating a lack of benefit from supplementation, and in some cases positive harm.  At first, this result surprised me. How can one explain it?  After all, we know that vitamin-rich fruits, vegetables and herbs are good for us.  Extracts from these anti-oxidant-rich foods have been shown to neutralize reactive oxygen species (ROS) in the lab.  Hence, it must be the case that fruits, vegetables and herbs are good for us because of their antioxidant content – right?

Wrong. As we all know, correlation does not always imply causation.  And it turns out that fruits, vegetables and nuts may improve our resistance to oxidative damage for reasons other than their antioxidant content.  A more likely reason is that these foods are rich in polyphenolic phytochemicals–such as bioflavanoids– that stimulate the cells in our bodies to turn on a transcription factor called Nrf2, which activates our “xenobiotic” defense system.  This xenobiotic defense system or Antioxdiant Response Element turns on the production of a number of  endogenous anti-oxidant enzymes–such as superoxide dismutase and glutathione peroxidase–that inactivate ROS species catalytically.  That means that unlike the antioxidant chemicals in foods–which quickly get used up one-for-one when neutralizating oxidant molecules–the anti-oxidant enzymes turn over thousands of times, and are thus far more potent and sustainable defenses.  In addition, these enzymes are produced in cells throughout the body, localized where they are needed most.

In short, empowering our in-born antioxidant defense system is much more effective than supplementing with chemical antioxidants.

But what is even more startling is that supplementing with endogenous antioxidants can actually suppress your body’s endogenous ARE defense system.  Startling, but not too surprising once you realize that the ARE system is homeostatically regulated. That means that your metabolism compensates for external changes by making the appropriate internal changes in order to restore a rough balance.   Just as body temperature, blood glucose, and countless other internal variables are regulated, our defenses against oxidative stress are regulated.

Homeostatic regulation, ubiquitous in biology, evolved to help us adjust to changing circumstances, and to conserve resources. If antioxidants are supplied from the outside, there is less need to spend energy and internal resources making our own anti-oxidant enzymes, so the organism turns town their production. In my earlier article, I surveyed studies showing that this is just what happens, concluding:

So it appears that, by consuming more antioxidants, we become dependent upon them and perversely reduce our innate ability to detoxify. With any let-up in the constant supply of external defenses, we become more vulnerable to oxidative and inflammatory attack. And the externally supplied antioxidants themselves are in any case much less effective than the endogenous ones.

I ended by recommending that we select foods and herbs not for their anti-oxidant content, but rather for their hormetic ability to stimulate our native ability to produce’s its own detoxifying antioxidant enzymes. At the top of that list are brightly colored and bitter foods and herbs, such as broccoli, blueberries, red peppers, curcumin, green tea and even chocolate.

The moral of the story:  When possible, build your own capacity rather than relying on external supplies.

Now on to vitamin D.  Not everyone realizes that this “vitamin” is actually a hormone — a secosteroid in the same family as other steroid hormones like testosterone and cortisol.  As a hormone, the primary function of vitamin D is to regulate levels of calcium and phosphorus in the bloodstream, thereby promoting healthy bone formation.  But vitamin D also regulates a number of other important processes in the body, such as activation of both the innate immune system and the adaptive immune system.

The diet can supply vitamin D as either D2 (ergocalciferol, from plants) or D3 (cholescalciferol, from animals), but it is most effectively synthesized in the skin by the action of UV-B rays in sunlight acting on 7-dehydroxycholesterol.  (Yes, it all starts with cholesterol!).  But neither D2 nor D3 — the molecules present in supplements or food — are biologically active forms of the vitamin.  The diagram at right shows how vitamin D must first be converted by hydroxylation to calcidiol (usually designated as 25 (OH) D, or just “25-D”) in the liver and then further hydroxylated to calcitriol (1,25 (OH)2 D or just “1,25-D”) in the kidney.  It is the 1,25-D form that is biologically active, binding to the vitamin D receptor (VDR) and activating a cascade of important biological functions, such as calcium absorption in the intestines.  So a well-functioning liver and kidney are required in order for vitamin D to be effective.

Vitamin D studies. Nobody doubts the important role of vitamin D in the body.  But are higher levels of a hormone like vitamin D–whether or not provided as a supplement– always a good thing?  Well, that is far from clear.  In a review of vitamin D studies in The End of Illness, David Agus, professor of medicine at University of Southern California, cites both positive and negative consequences of increased vitamin D levels.  On the positive side, a 2009 study presented by the Intermountain Medical Center in Utah, following 27,686 men older than 50 years over the course of a decade, found that those with the lowest levels of vitamin D had:

  • 90% higher incidence of heart failure
  • 81% higher incidence of heart attack
  • 51% higher incidence of stroke

Pretty impressive association!  And yet Agus also cites two negative studies worthy of comment:

  • A 2010 double-blind, placebo-controlled study, published in the Journal of the American Medical Association, found that older women who received annual oral high-dose vitamin D had an increased risk for falls and fractures.
  • A 2008 study, published in the Journal of the National Cancer Institute, found that vitamin D does not reduce the risk of prostate cancer, and furthermore that higher circulating levels of 25-hydroxyvitamin D may be associated with an increased risk of more aggressive forms of prostate cancer.

Correlation vs. causation.  Agus points out that most of the vitamin D studies are “observational studies” that show associations. They uncover a correlation bertween vitamin D levels and some other condition. But they don’t show cause and effect. The few mechanistic studies of vitamin D action were mostly carried out in cell culture, for example adding vitamin D to breast cancer cell cultures suppressed their growth.  But in real humans, vitamin D is part of a homeostatic regulation system.  Vitamin D doesn’t just do one thing, like promote bone growth.  It is involved in as the regulation of as many as 2000 genes, turning up the expression of some, turning down the expression of others.

So how do we interpret these associations? As Agus points out, in regard to the Utah study:

An association, however, does not prove cause and effect. Another way of looking at this study is to say it’s quite possible that a heart condition lowers vitamin D levels, directly or indirectly— by keeping people with health challenges indoors and out of the sun. Also, obesity throws another wrench into the problem because excess fat absorbs and holds on to vitamin D so that it cannot be properly used in the body. Hence, is low vitamin D in this study just a marker for those who were obese? It’s the old chicken-and-egg conundrum. The same can be said for hundreds of other such studies that link the health (or lack thereof) of an individual to levels of vitamin D.

This is the key point:  Low vitamin D levels may be a biomarker for other problems.  It may be the consequence, rather than the cause, of certain conditions such as heart disease or obesity. For the same reason, high vitamin D levels may be a biomarker for good health.  Agus quotes Dr. JoAn Manson, chief of preventive medicine at Brigham and Women’s Hospital:

People may have high vitamin D levels because they exercise a lot and are getting ultraviolet-light exposure from exercising outdoors. Or they may have high vitamin D because they are health conscious and take supplements. But they also have a healthy diet, don’t smoke, and do a lot of the other things that keep you healthy.

If vitamin D level in the blood is merely a biomarker, a consequence of good or bad health, then adding vitamin D to the diet will not necessarily improve your health.  To really know whether vitamin D supplementation is beneficial, we need to look at interventional studies, where supplements are provided, and the outcomes are compared with those of control subjects who don’t get the supplement.  In fact the two above-cited studies on the effects of supplementation on bone fractures in older women, and prostrate cancer in older men are two such interventional studies.  And they showed that vitamin D supplementation was harmful in both cases.  And note that the positive Utah study I cited above–showing a correlation between low vitamin D levels and elevated incidence of cardiovascular disease and stroke–was an observational study, not an interventional one.  The men in that study with the higher vitamin D blood levels and lower incidence of heart disease were not given supplements.

Vitamin D levels are homeostatically regulated in our bodies, and this process varies with your genetics and health.  As one examlple of this, people with lighter skin color and less melanin in the skin evolved to make higher vitamin D levels even with reduced sun exposure; the converse is true of those with darker skin. (This may explain why African Americans are at much higher risk for vitamin D “deficiency”, particularly if they live in higher latitudes and work indoors).  People vary widely in the level at which they regulate vitamin D levels in their blood — it tends to be homeostatically controlled in a given individual, but the “normal” level may vary between 8 and 80 ng/ml, or even more widely than that.  Vitamin D levels are are genetically controlled by 3 or 4 genes, and are under control of the vitamin D receptor.  (This homeostatic regulation of vitamin D levels will sound familiar to those who read my previous post, “Change your receptors, change your set point“).  As Agus notes,

When your cells are deluged with vitamin D…they will pull back on their sensitivity to vitamin D by reducing their number of receptors for vitamin D. But if there’s a perceived shortfall of vitamin D in the bloodstream, your cells will up-regulate— create more receptors for vitamin D— to become more sensitive to every vitamin D molecule that passes by. What happens, then, when we consume lots of vitamin D from unnatural sources such as supplements? (I use the term unnatural to imply that it’s not coming from the sun, which is a source of vitamin D that has built-in regulatory mechanisms.) No doubt our bodies are adept at adjusting using their feedback loops as I just described, and the constant surplus of vitamin D means our cells are constantly down-regulating. If we took the supplemental vitamin D away, our cells would up-regulate to make up the difference. Vitamin D has multiple downstream signaling molecules, for the vitamin D receptor signals several reactions.

So if you take vitamin D supplements, and vitamin D is regulated homeostatically, your body will turn down its endogenous production of vitamin D.  If you believe that vitamin D is a “biomarker” of good health, do you really want to turn down the upstream processes that synthesize vitamin D?  Think about that before you pop a vitamin D capsule.

Unintended consequences.  Even worse, taking vitamin D supplements may actually suppress the immune system.  This “alternative hypothesis” of vitamin D has been put forward by Trevor Marshall and Paul Albert.  Supplementation with vitamin D will tend to increase levels of the inactive form of vitamin D–that is,  25-D.  Conversion of inactive 25-D to active 1,25-D in the kidneys is not immediate, and may not be efficient, particular if kidney function is less than optimal.  Now here is the problem:  While both the inactive 25-D and active 1,25 bind to the  vitamin D receptor (VDR), only the 1,25-D turns on the VDR, allowing it to perform its beneficial functions; the inactive 25-D actually inhibits the VDR.  This is a problem because the VDR is the “gate-keeper” of the innate immune system, regulating over a thousand genes. So elevated levels of 25-D can result in immunosuppressive effects.  As Albert writes in Vitamin D: the alternative hypothesis:

Indeed, the secosteroid 25-D may exert palliation on the innate immune system not unlike the way corticosteroids exert palliation on the adaptive immune system. So is it possible then that supplemental vitamin D is now perceived as a wonder substance simply because it effectively palliates the inflammation associated with diseases across the board? If so, this would certainly explain why its effects are most noticeable in the short-term and why efficacy often diminishes in the long-term.

And we need to also take into account the regulation of vitamin D levels through homeostatic feedback processes.  Consider that it is typically the 25-D form of vitamin D–not the biologically active 1,25-D– that is measured in blood tests.  And there is very little correlation between the active and inactive forms, as shown in the the figure below, from a 2009 study by Blaney et al., published in the Annals of the New York Academy of Sciences in a sample of 100 Canadian patients. As the authors note, while  many of the subjects had very low levels of 25-D–the type reported in most blood tests–most of them had levels of 1,25-D elevated above the normal range. Can those subjects with low levels of 25-D but elevated levels of the biologically active 1,25-D truly be considered vitamin D deficient?

Because low levels of 25-D are often associated with inflammatory conditions such as cardiovascular disease and autoimmune disease, people jump to the conclusion that low 25-D levels are a cause of the inflammatory condition.  On this point, listen again to Albert:

Yet, the alternative hypothesis must be considered – that the low levels of 25-D observed in patients with chronic disease could just as easily be a result rather than a cause of the inflammatory disease process. Our research suggests that this is the case. Indeed we have found that 1,25-D tends to rise in patients with  chronic disease and that these high levels of 1,25-D are able to downregulate through the PXR nuclear receptor the amount of pre-vitamin D converted into 25-D, leading to lower levels of 25-D.  I describe this finding further in my paper.  So are we really facing an epidemic of vitamin D “deficiencey” or are we simply beginning to note more signs of an imminent epidemic of chronic disease – an epidenmic which would be exacerbated by increasing the amount of vitamin D added to our food supply?

So the body is making enough active vitamin D to deal with inflammation–maybe even too much, leading to downregulation of the inactive 25-D precursor.  Trevor Marshall has also pointed out that elevated levels of 1,25-D may result from impaired activity of the  VDR, which is essential for innate immunity.  The excess 1,25-D can cause problems with other secosteroid receptors in the body, such as the thyroid receptor.  But adding more 25-D, beyond what is needed, will tend to only further inhibit the VDR, interfering with its beneficial anti-inflammatory actions, and impairing innate immunity.  In other words, well-intended supplementation with Vitamin D3 may actual backfire. Something to think about!

Marshall is currently conducting studies with a protocol involving restriction of vitamin D and use of an agonist drug that binds to the VDR receptor, upregulating it, and acting as an immuno-stimulant to treat immune disorders like arthritis and multiple sclerosis.  Marshall’s protocol is controversial, because it flies in the face of the orthodoxy about Vitamin D.  He acknowledges that vitamin D supplementation can indeed deliver some short term benefits because it acts as an immuno-suppressant–in much the same was as corticosteroids like prednisone. But just as prednisone is useful for acute treatments, yet is harmful if taken chronically, the immune-suppresant effects of vitamin D on the VDR may be detrimental.

One need not go to the extent of restricting or avoiding vitamin D to exercise some caution about actively supplementing it.  If supplementation has risks, is there anything you can do to ensure adequate levels of the active form of vitamin D?  Certainly, it is important to have at least an adequate level of D3 entering the liver, by eating foods rich in vitamin D,  and through biosynthesis from adequate exposure to sunlight.  But you also want to make sure that the conversion processes to 25-D in the liver and 1,25-D in the kidneys are functioning well.  Which means eating a low-inflammatory diet — that is, one that is low in sugars, processed omega-6 vegetable oils and other pro-inflammatory compounds.

Here is the takeaway from this vitamin D story, together with my earlier post about antioxidants: Inflammatory conditions, such as heart disease, infection or autoimmune disease are often associated with reduced levels of certain biomarkers in the blood,  such as antioxidant vitamins or hormones.  Our natural instinct is to conclude that these are “deficiencies” that need to be corrected.   While that may sometimes be the case, particularly in extreme cases, you should keep in mind the direct supplementation with additional vitamin or hormone may actually be counterproductive–by shutting down or impairing your body’s own ability to mount it’s own defense against oxidative stress and inflammation.

Rather than taking hormone and vitamin supplements, it is more effective to stimulate your body to strengthen its own defense and detoxification systems.  I’m not against all supplementation — for example, I believe that ingestion of phytochemical-rich vegetables and herbs is useful as a hormetic stimulus.  But I think we have to overcome the simplistic notion that if X is a good thing, we should consume more of X.

The body is more than a repository for chemicals — it is a self-regulating organism with hundreds of complex and dynamic feedback loops, evolved to enable us to adapt to changing circumstances and meet many challenges.  We should take care that what we ingest is used to build up our natural capacities, not subvert them.


February 11, 2013 update:  For suggestions on how you might be able to get the benefits of vitamin D supplementation without the possible downsides, see the more recent post:  An alternative to vitamin D supplements?

December 7, 2013 update:  A comprehensive review of 290 vitamin D interventional studies and 172 randomized trials, published in this month’s Lancet, adds further support my thesis that vitamin D levels are a consequence, not a cause, of health status


Low serum concentrations of 25-hydroxyvitamin D (25[OH]D) have been associated with many non-skeletal disorders. However, whether low 25(OH)D is the cause or result of ill health is not known. We did a systematic search of prospective and intervention studies that assessed the effect of 25(OH)D concentrations on non-skeletal health outcomes in individuals aged 18 years or older. We identified 290 prospective cohort studies (279 on disease occurrence or mortality, and 11 on cancer characteristics or survival), and 172 randomised trials of major health outcomes and of physiological parameters related to disease risk or inflammatory status. Investigators of most prospective studies reported moderate to strong inverse associations between 25(OH)D concentrations and cardiovascular diseases, serum lipid concentrations, inflammation, glucose metabolism disorders, weight gain, infectious diseases, multiple sclerosis, mood disorders, declining cognitive function, impaired physical functioning, and all-cause mortality. High 25(OH)D concentrations were not associated with a lower risk of cancer, except colorectal cancer. Results from intervention studies did not show an effect of vitamin D supplementation on disease occurrence, including colorectal cancer. In 34 intervention studies including 2805 individuals with mean 25(OH)D concentration lower than 50 nmol/L at baseline supplementation with 50 μg per day or more did not show better results. Supplementation in elderly people (mainly women) with 20 μg vitamin D per day seemed to slightly reduce all-cause mortality. The discrepancy between observational and intervention studies suggests that low 25(OH)D is a marker of ill health. Inflammatory processes involved in disease occurrence and clinical course would reduce 25(OH)D, which would explain why low vitamin D status is reported in a wide range of disorders. In elderly people, restoration of vitamin D deficits due to ageing and lifestyle changes induced by ill health could explain why low-dose supplementation leads to slight gains in survival.






  1. Ulrik

    Excellent, thought-provoking post. Extrapolating your point, I guess for every nutrient we need to evaluate the optimal dose, and how to get it (this is something Paul Jaminet also often talks about). We can add to that also how often, and whether to adjust according to diurnal and annual cycles.

    E.g., intermittent fasting, or going low-carb in the winter, and higher carb in the summer through seasonal eating. That accounts for the fuel nutrients, fats and carbs.

    Then we have amino acids, which is obviously a quite complicated story. My thinking so far is that it’s best to vary it up as much as possible, aiming for complete sources, but of widely different amino acid profiles. Basically, nose-to-tail eating.

    For minerals and elements, I feel supplementation might be necessary, dependent on where you live (obviously, there’s no endogenous production of these). Some have to be carefully balanced, e.g., potassium vs sodium, and copper vs zink, etc.

    For “Vitamins” like vitamin D, it’s more dicey, and it’s great that you’ve dug through the research. I look forward to your thoughts about other micronutrients.

    • Todd


      I think we tend to obsess too much about carefully balancing or cycling nutrients. Let’s keep it simple: avoid inflammation and get adequate intake of natural fats, proteins, and phytonutrient-rich vegetables and fruits containing adequate soluble fiber. While it is obviously true that we can’t synthesize essential minerals, most of us–unless severely malnourished–get sufficient amounts of these in a balanced diet. If you remain healthy, your metabolism can likely take care of absorbing, utilizing and balancing the minerals it needs. Where there are mineral deficiencies, it is often due to malabsorption (stemming from diet-induced inflammation, high-phytate grains, hyperinsulinemia, and impaired gut health) rather than a true lack of minerals in food.

  2. Ron

    WOW, I just took my very first D-3 supplement yesterday! I’ve done so because of performing my own [limited?] research and following the NuSi team who, not only outwardly support the supplement, but take it themselves. No, haven’t gotten my D levels checked recently, but with the winter rapidly approaching and less and less time being spent outside, I thought it to be a fairly reasonable health decision…

    I respect all of the reading/opinions/research on these subjects, but who or what should I believe anymore? That’s MY conundrum!

  3. Leonardo

    Interesting perspective.

    But in the case of Vitamin D, which is practically impossible to get adequate levels from food, wouldn’t a low level simply be a result of inadequate sunlight exposure? And if so, wouldn’t supplementation be the best solution?

  4. Ben

    I read on one of the paleo blogs like Chris Kresser or Michael Eades that some people (genetic) can’t synthesize vitamin D through the skin via sunlight very well and need supplementation.

    • Todd

      Ron, Leonardo and Ben,

      Who to believe? I respect Attia, Taubes, Kresser and Eades. But go back and read their evidence and arguments for supplementing with vitamin D. As I emphasize in my article, nobody doubts the correlation between low levels of measured 25-D and higher incidence of inflammatory conditions like heart disease, cancer, infection, and autoimmune disease. But do those guys provide any research showing that low vitamin D (25-D) actually causes these health problems? Or is it mere association–in which case cause and effect may be reversed? Are there any interventional studies showing that supplementing with vitamin D has any long term benefits? (Short term reduction in infections may be due to immunosuppression, not a desireable long term strategy).

      A very small part of the population may indeed be genetically incapable of synthesizing vitamin D from sunlight, or may consume foods totally lacking in vitamin D (although that would be rare, given the prevalence of government-mandated vitamin D enrichment into dairy and other foods). But for the rest of us: the Minimum Daily Requirement of vitamin D was established based upon correlations, before the science understood the regulation of 1,25-D and the role of the Vitamin D Receptor. The whole point of my article is that the conventional understanding of what constitutes an “adequate” level of vitamin D may be flawed and in need of being revisited. I think it may be more productive to focus on what dietary and lifestyle factors favor the proper utilization and regulation of vitamin D, and the function of the vitamin D receptor.

      I welcome evidence and arguments that challenge my thesis.

      • http://www.ncbi.nlm.nih.gov/pubmed/21135266

        This was a study that showed Vitamin D supplementation for a year in overweight men increased their Testosterone levels. They went from in the deficient range (where many doctors would start hormone replacement treatment) to the low end of the normal range.

        Testosterone has been shown to improve Metabolic syndrome, and aid weight loss & waist circumference reduction.

        • Sabine

          That is a study which is pretty flawed for me – they are overweight, so there is a good chance they don’t go outside much, especially not when the sun is shining, and even when they do, they are likely to cover up more than a man with a muscular body.

          Now the funny thing is, there could be a chance that as overweight men, they actually have an increased requirement for Vitamin D, but that should be compensated by the extra amount of skin they have due to their figure.

          If you now imagine, they need more Vitamin D than someone skinny, but are less likely to expose their skin to the sun (sweating issues, cultural issues, embarrassment, sedentary lifestyle), then disaster is clearly on the way.

          Of course if supplements helped them towards health, fair enough, but I would imagine some weeks at the beach in swimming trunks may have been just as effective.

      • Zorro

        “But do those guys provide any research showing that low vitamin D (25-D) actually causes these health problems? Or is it mere association–in which case cause and effect may be reversed?”
        Now let’s put it the other way around: Do you provide any research supporting your point of view?

        • Todd


          My “point of view” is skepticism regarding purported benefits of vitamin D supplementation. I’m not claiming with any certainty that Vitamin D supplementation is useless or harmful. I’m simply claiming that the positive case for vitamin D supplementation is inconclusive. The evidence doesn’t not support interventional benefits. I think I’ve made the case. So I’m not sure what you mean by evidence supporting “my point of view”.

          The strongest evidence for my skepticism is the figure in the above post, showing essentially zero correlation between levels of 25-D (what your doctor measures) and 1,25-D (the biologically active form of vitamin D). From this we can directly deduce that if your doctor measures a low 25-D status, this tells you nothing about any meaningful measure of your biologically relevant calcitriol levels.

          Beyond this, there are additional concerns about flooding your body with a secosteroid with broad systemic effects that typically show up in the long term, regardless of any short term symptomatic relief. Google the history of supplementation with predisone, testosterone, growth hormone and other steroid hormones. Great short term benefits. Longer term problems.


  5. Nate

    Thanks for the very well written post. Vitamin D has become a very hot topic. There are hundreds-if not thousands- of correlation studies showing beneficial effects of vitamin D. Of course, as you so rightly point out, correlation is not causation. The largest flaw in the logic of the vitamin d proponents is that obesity has been shown to cause vitamin d deficiency (through sequestration in fat tissue)-but obesity itself it correlated with many different poor health outcomes.

    While by no means an expert, here is my take on the vitamin D issue. As I understand it, there are three mechanisms of action of Vit. D: endocrine, paracrine, and autocrine. Endocrine activity is well established, causing bone mineralization, and its deficiency causes rickets (osteomalacia in adults). 1, 25 vit. D is the endocrine (active) form of vit D. Symptoms of rickets do not appear until the vitamin d level is very low. No doubt about it, the treatment for rickets is supplementation with vit. D.

    The controversy comes in the paracrine and autocrine activity of Vit. D. Paracrine activity refers to hormonal activity that occurs in tissue close by-while autocrine activity refers to to a cell taking up 25 vit D, converting it to 1,25 vit D, secreting the vitamin d-which then acts on the same cell.

    One of the reasons autocrine and paracrine activity are controversial is that it is usually claimed that they reduce the incidence of other diseases-for instance, colds, cancer, multiple sclerosis, depression, asthma, etc. The list of diseases claimed is very long. But rather than causing a single, distinct disease, such as rickets, deficiency here causes an increase in the incidence of a variety of other diseases-with other causes.

    The vitamin D advocates claim that a “normal” level of vitamin d-in order to have good functioning of autocrine and paracrine effects-is higher than that needed for endocrine effects.

    In the past, health benefits have been claimed for other vitamins by trying to obtain a “supranormal” level of the vitamin-such as antioxidants, vitamin E, vitamin C. Under scrutiny, these claims have failed.

    The vitamin D advocates, however, make a different claim-that the “normal” level is higher than what we see in order to induce rickets. If they are correct, and the normal level is higher, then supplementation is probably healthful.

  6. Nate

    The last comment was getting a little long, so I split it in 2.

    There is evidence for an autocrine effect in cancer prevention. Apoptosis is “programmed cell death”, by which a cancerous cell “commits suicide”. Apoptosis is a vitamin D mediated, autocrine effect:


    There are also randomized controlled trials showing decreased cancer incidence in people supplemented with vitamin D:


    Another autocrine effect of vitamin D is the secretion of Cathelicidin-an antimicrobial peptide:


    There have been RCTs showing decreased infections in people supplemented with vit d, and other RCTs showing no effect.

    It’s all very difficult. What really is the “normal” level for vitamin D? If the lower level is correct, trying to supplement to a “supranormal” level will probably not help, and may harm. On the other hand, if the higher level is correct, supplementation will probably help.

    I’ll tell you what we do in our family. I take-and give my kids-supplements for half the year-winter. That way, there is a period of no supplements-but plenty of sunshine.

    Its completely anecdotal, but since we started supplementing with vitamin D, no one has got cancer! More to the point, my kids are remarkably healthy. They are the ones who always get the award at the end of the year for perfect attendance-no school days missed for illness.

    • Todd

      Hi Nate,

      Many thanks for bringing to my attention to the studies you linked. A few thoughts:

      1. I wonder about the significance of the cell culture studies. Since they consider only the direct action of the 1,25-D on hormone signaling and apoptosis, they leave out the regulatory effects on the Vitamin D receptor (VDR) upon over a thousand genes in other cell types, and other secondary effects such as feedback downregulation of 25-D levels.

      2. Regarding the 2008 cancer intervention study by Lappe et al. I don’t have access to the full study, just the abstract you linked. But, as one reviewer noted, the reduction in cancer incidence appears to be statistically insignificant. Out of about 1200 women, there were 4 cancers in the supplementation group, versus 7 in the placebo group. Four years is also a fairly short time to be able to draw conclusions about cancer mortality. So I’m still looking for interventional studies that show statistically significant long term benefits of vitamin D supplementation.

      3. You are certainly right to point out a possible beneficial effect of vitamin D’s induction of cathlecidin as a result of VDR activation. This may in part explain the reduced rates of infection that have been noted following vitamin D supplementation. (http://news.harvard.edu/gazette/story/2012/08/vitamin-ds-impact-on-infection/), although the effect is not consistent (http://www.sciencedaily.com/releases/2012/10/121002161751.htm), and suppression of infection or immune response is what I would consider to be a short term response. We can of course also suppress infections with antibiotics and apply steroids to dampen immune response. I wouldn’t hesitate to do this on an acute basis in an emergency. But my general approach to health is to use hormesis and other methods to stimulate and strengthen the body’s defense and repair mechanisms, rather than resorting to palliative approaches which could weaken us in the long term.



      • Here is the link to the full study by Lappe et al in your #2 point above:
        It looks like there was a total of 50 participants who got cancer during the course of the study. As far as I can tell the Ca + D group had less cancer than the placebo group and it was a P value of .013; less than .05 is statistically significant.

  7. Bill Rowles

    Let’s be quite clear that D3 synthesis via UV action on the skin, can raise levels of 25(OH)D substantially. I’m wondering whether there exists in correlation with elevated incidence of autoimmune diseases and cancer in Mediterranean regions as a consequence of VDR inhibition?

    It’s also clear that sunlight synthesis appears to be no different in effect to supplementation.

    I honestly doubt hormesis is relevant in this case 25(OH)D is stored in the liver, released and converted as required. Homeostatis is the ruling process, not hormesis.

    • Todd


      No disagreement about the effectiveness of sunlight in vitamin D synthesis, and the equivalence of supplemented vs. synthesized 25-D. Quoting from what I wrote in my post

      The diet can supply vitamin D as either D2 (ergocalciferol, from plants) or D3 (cholescalciferol, from animals), but it is most effectively synthesized in the skin by the action of UV-B rays in sunlight acting on 7-dehydroxycholesterol.

      I’m also not sure where you get the idea that I’m confusing hormesis with homeostasis. I’m clear on the difference between these two processes. Hormesis is a biological phenomenon whereby a beneficial effect (improved health, stress tolerance, growth or longevity) results from exposure to low doses of an agent that is otherwise toxic or lethal when given at higher doses. It has its roots in a set of defense and repair processes which act to resist damage and restore function. That is the connection between hormesis and homeostasis — a set of regulatory processes by which an organism acts to maintain a relatively constant internal environment. The connection is that the stresses of hormesis activate homeostatic processes to result in what Mark Sisson has termed “supercompensation” — a strengthening of defensive capabilities. So the hormesis of weight lifting induces muscle trauma and supercompensating muscle repair. Cold showers, intermittent fasting, and Stoicism all work by similar processes of super compensation. None of these processes would work without homeostasis. So homeostasis is a necessary condition for hormesis.

      But the action of homeostasis is not always a response to hormesis. Sometimes it just involves a response to a minor disturbance, like the physiological responses to acidifcation of the blood or a drop in body temperature, so as to return the organism to the starting point. So in the case of the vitamin D (25-D) storage or synthesis, there is homeostasis, because these levels are regulated. No hormesis is involved. And I never said it was involved.

      Why does my article have to do with hormesis, you may ask? Well, not all of my articles are directly about hormesis, even though that’s the main theme of my blog. But the connection is spelled out very clearly in the last 3 paragraphs of my blog post above — easy enough to scroll up and read them.

      • Bill Rowles

        Hmmm – still implicit, Todd.

        I think the crux of it is more a question of just how much D we thrive on. The arguments that we adapted to have less melanin as we migrated northwards are compelling, and it would seem that this pre-hormone is critical to optimum health.

        Since your article is speculative, I can also speculate..

        The Inuit obtain D from diet, and are likely replete, despite virtually nil by UV synthesis. In effect, this could be seen to be a kind of “supplementation”.

        I think the data from Grassroots Health are the most interesting, and no-one is making a fortune out of promoting supplementation – it’s way too cheap. So we can rule out “conflict of interest” from those promoting supplementation – er, but not in the case of those promoting sun lamps (!)

        It seems to be the case, though, that there is a wide variation in individual requirements.

        What I find most “challenging” is the assertion that 25(OH)D can actually cause VDR inhibition – unless we entertain the concept of liver saturation. But then, surely, we would be at the toxicity threshold?

        My main point remains – is there any epidemiological evidence to support abundant sunlight exposure with VDR inhibition, as might be expected in Mediterranean climates? (Presumably elevated incidence of the cancer and autoimmune disease, as reported by Grassroots Health)

  8. I wonder if supplementation from more complete food sources, like cod liver oil with no synthetic vitamins added, would have a different effect due to the “synergy” (Weston Price’s term) between vits. A and D.

  9. Over on Seth Roberts’ blog there has been a steady stream of posts relating to D supplementation with the general theme that it seems to matter *when* you take D. If you take 4000 or so first thing early in the morning, it helps you sleep better and thus feel more alert when awake. If you take D later in the day, it does not have this beneficial effect.

    The working hypothesis is that our bodies expect to see sunlight in the morning and getting an early pulse of D simulates that, helping set our circadian clock better. Sleeping better in turn promotes health in all sorts of ways – if D helps you sleep better, that boosts the immune system.

    Most existing studies of D supplementation do not instruct people to take it at a particular time, so they might be missing out on this benefit.

    • Bill Rowles

      I don’t “buy” this at all.

      25(OH)D is not released into the bloodstream until hours after UV exposure, and is then stored in the liver, being released “as required” and converted to the active form in various sites, but primarily the kidneys.

      In supplementation, it seems to be irrelevant whether you take 42,000iu weekly, or 6,000iu daily, let alone what time of day you take it.

      Everything I’ve seen on this topic is subjective, and has not been studied.

    • I notice that when I take vitamin D I get sleepy right away. So I take mine at night to help me sleep better.

      Also, when I sun bathe at noon, or use light therapy regardless of the time of day, I sleep a lot deeper that same night.

      One benefit of light stimulus over just vitamin D suplementation might be the production of serotonin, which then gets turned into melatonin at night.

  10. RJ

    This came at a great time since I just finished my bottle of Vitamin D pills. I think I’ll hold off on buying another bottle for the time being.

    I was convinced that vitamin D really helped me with depression. After supplementing, I’d never feel as low and hopeless as I did before. Maybe this improvement in my mood was caused by something else. I’ll stop taking the D supplements and see how I feel.

    Thanks for the insightful post.

  11. Bill Rowles

    Trevor Marshall doesn’t strike a chord for me – here he gets a sound rebuttal:


    • Todd


      I followed your link to the letter by Marshall and the response by Hanley. Not sure I would call Hanley’s response a “rebuttal”. Hanley doesn’t really address Marshall’s main challenges to the consensus view about vitamin D “deficiency”, nor does he discuss the Marshall protocol. Hanley’s letter in fact acknowledges errors that Marshall pointed out an article that Hanley co-authored, and he agrees with Marshall that the 1,25-D is the most biologically active form of vitamin D. He then goes on to make some rather minor points regarding malabsorption syndromes and osteomalacia, where low vitamin D levels result in poor bone mineralization. I don’t think anyone (myself, David Agus or Trevor Marshall included) doubts the reality of true vitamin D deficiencies in cases such as these, or rickets. But that is tangential to the main question regarding whether “vitamin D deficiency” should be re-defined as broadly as it has been in recent years, and whether we should supplement at levels far higher than those need to prevent rickets or bone demineralization.

      Let me be clear here that I don’t follow everything that Trevor Marshall advocates. For example, I’m far from convinced about the soundness of his “Marshall protocol” that actually attempts to drive down levels levels of 25-D, including avoidance of sunlight, in order to treat certain chronic inflammatory and autoimmune disorders. However, I do believe that he and David Agus have at least raised valid reasons to be skeptical that active vitamin D supplementation is an unalloyed good thing. In that respect, they have done us a service by pointing to the lack of well-controlled positive interventional studies, the existence of studies showing deleterious effects, and the reality that vitamin D, as with any hormone, is subject to feedback regulation. The fact that vitamin D’s interaction with the VDR has widespread effects on regulation of hundreds of immune modulating genes, many of which are poorly understood, should give anyone pause. Vitamin D may indeed provide many people with short term benefits, e.g. reports of controlling asthma or depression. But what of the long term effects? Cortisone, predisone, and human growth hormone also have amazing short term benefits — but I wouldn’t advise use them chronically.

      I’m not anti-vitamin D. I just don’t think the case has been made for routine and long-term supplementation, except in cases of severe deficiency.

      Thanks for your note!


  12. Ron


    This may be a personal question, and delete this if it is :), but do you take any supplements at all? Mere curiosity.

    • Todd


      It’s a fair question. I do not take any vitamin or mineral supplements, or any hormones — not because I fear them, but because I believe I get the nutrients I need in adequate amounts from wholesome meats, vegetables and other foods, and I don’t have any apparent problems with absorption. But I also don’t necessarily trust published “standards” of how much is enough.

      I do not have a fully developed theory of whether and when supplementation is beneficial or not. I’m still doing a lot of reading on this. There is one pill I take every day, which I won’t reveal at this point, other than to say it is not a supplement, but a mixture of “hormetic” compounds which induce a beneficial endogenous antioxidant response and significantly shortens my recovery time after workouts.


      • Ron

        “But I also don’t necessarily trust published “standards” of how much is enough.”

        Totally agree!

        “…which I won’t reveal at this point”

        Thanks for the cliffhanger!

  13. pieter d

    Thank you for this post. A few thoughts and questions:

    Would you think that the health benefits of Vit D, if they are hormetic in nature, would have a U-shaped curve, with a ‘sweet spot’ for optimal health, much like exercise?

    You mentioned Mark Sisson and evolutionary reasoning, so wouldn’t you think that comparing vit D levels from people living most of the time inside with levels from ‘outside living people’. Do you have any data on this?

    Thanks again.

    • Todd


      While I sometimes take inspiration from the observations of “paleo” authors like Mark Sisson and Robb Wolf, I’m not convinced that so-called “evolutionary reasoning” is a sound methodology. The evidence for what our ancestors ate and how they lived is sparse and often speculative. There is great variety in human dietary practices and even genetics. And of course, our more primitive forebears did not necessarily live longer or exhibit great health. It’s wise to balance these anthropological or evolutionary studies and speculations with modern physiology and biochemistry. Of greatest interest and importance, in my view, is a sound understanding of homeostatic regulation — how our body and metabolism responds to and compensates for what we ingest and what we do.

      I think that it is too simplistic and reductionistic to posit a single optimum or sweet spot for individual nutrients or biomarkers — whether they be macronutrients like fats, or hormones, vitamins or minerals. Certainly at the extremes, very low vitamin D is associated with rickets, and very high levels with toxicity. But there is no single optimum level for all individuals in all health conditions. These chemistries need to be considered as parts of a complex, dynamic system that is in constant flux. A level that represents “deficiency” for one person may be adequate or excessive for another. In certain cases it is the balance, not the absolute level that is important. For example, Vitamin D exists as part of a regulatory system that includes Vitamin A, calcium and zinc.

      Furthermore, as my article indicates, Vitamin D levels – when measured as vitamin D3 or 25-D — may be more of a consequence than a cause of health, and do not correlate well with the biologically active form, the 1,25-D. I have no doubt that people who spend more time outdoors have higher 25-D levels — because they are synthesizing the precursor in their skin. And they are healthier. But so what? Are they healthier BECAUSE they synthesize more Vitamin D? And should we replicate this by supplementing with Vitamin D? That is not proven.

      Wealthy people own more sports cars, but they are not wealthy BECAUSE they buy sports cars. And buying a sports car will not make you rich.

  14. Nate


    A little off topic, but did you see this article on the mechanisms of action for omega-3 PFA’s?


    Hormesis makes another appearance!


    • Todd


      Thanks for the excellent article. It potentially resolves a mystery I had always wondered about: How can such easily oxidized n-3 PUFAs, which go rancid and become harmful when oxidized, exert such beneficial biological effects? The hormesis explanation is not only appealing, but also has good experimental support from the article. I think this rationale also supports another line of thinking that I’ve been intrigued by: namely, that while chronic exposure to elevated levels of reactive oxygen species (ROS) is generally detrimental, we in fact benefit from intermittent, more selective exposure to oxidative “stress”. Chris Masterjohn likes to frame oxidation as a means of cellular “communication”. Stamping out this communication is not desireable. Rather, what we want is a well-regulated system of oxidative communication.


  15. alphagruis

    Very interesting post.

    A nice and now well documented example of low 25 D as a consequence rather than a cause of illness is primary hyperparathyroidism. Removing the tumor(s) spontanenously restores “normal” 25 D levels in blood.

    Supplementing vit D in these patients before bad glands parathyroidectomy is quite dangerous.


    • fay louise

      hi, i want to say that low vitamin d is a consequence and a cause and a red flag of dysfunction processes in the body.

      the example you make of HPTH and vitamin d: the reason why the “vitamin d level spontaneously improves” suddenly miraculously after a parathyroidectomy is…. because the out of control PTH has stopped converting the available vitamin d that is available,.. so it in-a-sense stabilizes, though it is often still very low, but will improve/raise just because the offending gland/s are removed.

      in that sense it cures the vitamin d deficiency at causative level, if that person would otherwise have a normal vitamin d level, in there day to day life.

      being speculative, who is to say that the parathyroid gland would never have had developed over activity if there was more than ample vitamin d in circulation in that persons lifetime?
      we can not prescribe behavior to nutrients for our convenience of understanding, we have to look at the physiology and mostly we dont know is the long and short of it,. nutrients do not work in isolation and to discount that is dumb, magnesium, boron are crucial as well for parathyroid health,.. so who knows? no one does the testing on these nutrients during lifetimes to see when and how.

  16. David


    Dr Joseph Mercola claims that in winter, the best way to get D3 is from his tanning beds. http://tanningbeds.mercola.com/

    I see some support for this idea at:

    What do you think of Mercola’s claim?

    • Todd

      An advantage of tanning (or direct sun exposure) over supplements is that vitamin D synthesis in the skin is self-limiting, so toxic build up is unlikely. I’m a bit skeptical of tanning beds, because even though brief, the rate of UV exposure is much higher than normal, more of the body is exposed, and the risk of skin cancer is elevated (http://www.cancer.gov/newscenter/entertainment/tipsheet/tanning-booths). If you are going to use tanning beds or spend a lot of time in the sun, the sane approach is to build up a base slowly. If you are pale and suddenly increase your exposure, your risk of burning (and cancer) are elevated than if you build up a base level of melanin in the skin.

      The bottom line, however, is that claims that most of us are “deficient” of Vitamin D are overblown — even in the winter. Rickets may have been a problem during the Great Depression, but not today. Many other factors besides vitamin D affect calcium absorption, so we can’t blame osteoporosis on vitamin D deficiency. Getting moderate sun exposure and eating a diet with a good source of animal and fish fat in the diet provides enough vitamin D for most of us.

  17. David Leitner

    A bit off-topic, but…

    What is your opinion on supplementing turmeric or standardized circumin?

    • Todd

      Tumeric is one of the few things I “supplement” — though I’m not sure it technically should be considered a supplement, since it is not a matter of correcting a dietary deficiency, as much as it is one of stimulating natural defenses. It is a Nrf2 activator, known to upregulate endogenous antioxidant enzymes. I have found it personally effective in reducing muscle soreness and improving post-workout recovery. I’ll be posting more on that at some point. For now, you might check out my post, “The case against antioxidants“.

      • David Leitner

        Thanks, Todd. Turmeric is one of the few things I take. I was not aware of the NRF2 connection, but I know turmeric seems to be very good. I love your work. Keep it up!

  18. Julie in Houston

    I’m preparing for pregnancy in the next 6 months. I’m reading a lot of support for the Green Pastures fermented cod liver oil/butter blend because it carries with it the vitamins needed to metabolize D. Is this something you’d recommend at this point. I hear/read so much conflicting information that it’s hard to decipher what’s best. Do you have any other recommendations for pre-natal supplements? I know Chris Kresser speaks about supplements quite often but I don’t want to break the bank! Any thoughts on pre-natal supplementation would be much appreciated. Love your info!

  19. Chris Oldglory


    Thank your the great article.

    Would you through fish oil in this as well? In other words, most primal/paleo folks say don’t worry about supplements EXCEPT vitamin D and fish oil. With your article pointing to the fact that perhaps supplemental vitamin D is not as beneficial as we think, should we be supplemental fish oil either?

  20. Conrad

    Unfortunately, writings like this tend to do more harm than good. Sure, it’s good to question things. It seems by the logic of this article that I should perhaps limit my water intake and keep my hydration at a low level to upregulate the hormones that signal my body to store water, since of course that is controlled homeostatically.

    Seems like this article is full of a lot of “could be’s” and very little good science. In light of all the good info currently on vit d supplementation, I’ll wait for some better info before jumping ship.

    • David Leitner

      Conrad, what harm is being done? Todd is raising important questions. Your analogy is not accurate. Is water a supplement or a required nutrient?

      • Conad

        My analogy is correct. Vit D3 is not merely a supplement, it also is a required nutrient. If it wasn’t then we wouldn’t even be talking about it. If we put water in a capsule and market it, is it no longer a required nutrient? No, that doesn’t change, supplements aren’t inherently inferior. Chemicals are chemicals, your body doesn’t necessarily know the difference. Ever heard of molecular mimicry?

        I’m not against healthy skepticism. I’m against skepticism that doesn’t understand the facts. I’m against stirring the pot to create drama.

        The harm I see is in taking a substance that is showing great promise in good solid research. A substance that more and more people are taking and improving their health with and throwing confusion in to the mix.

        This article lacks scientific substance and depth in comparison to others who are finding objective data to support maintaining optimal levels. As an example, the author apparently doesn’t understand the immune MODULATING effects of this substance as he didn’t give any acknowledgement to it when addressing suppression of the immune system. This is often a good thing and Vit D doesn’t just keep suppressing the immune system more and more the longer you take it.

        • Todd


          You suggest that I am trying to “stir the pot to create drama.” That’s not my intent. I’m just trying to get at the truth, and present the results of what I found. I”m open to any new information that would warrant changing my mind.

          You say that the article lacks scientific substance. In the above article I cited a substantive studies, published in reputable journals, that found negative outcomes (increased bone fractures and higher incidence of prostrate cancer) from vitamin D supplementation. I would like to hear your specific objections to those studies.

          You and I agree that both water and vitamin D are essential for human life. Beyond that, I think the analogy breaks down:

          1. We need to consume water because we can’t manufacture it in our bodies. By contrast, we can manufacture our own vitamin D–starting from a cholesterol derivative–by the action of UV-B in the skin.

          2. You are correct that both Vitamin D3 and water levels in the body are “regulated”. In the case of water, excretion and perspiration are “regulated” by salinity sensors in the kidneys. But this is very different that the feedback regulation of vitamin D, which is essentially a hormone. You would have to ingest extreme amounts of water — more than about 15 liters — to cause health problems such as hyponatremia. By contrast, vitamin D has hormonal action via ligand-receptor binding that initiate a cascade of genetic and physiological effects. 25-D levels are subject to feedback regulation by the biologically active 1,25-D form of the vitamin, via receptor binding to the VDR. (http://ajprenal.physiology.org/content/289/1/F8.full) Supplementing with high levels of D3 will not only downregulate vitamin D synthesis in the skin and liver; but by binding to the VDR, which in turn regulates more than 200 genes, many of which are associated with the innate immune system and cancer.

          Drinking a lot of water can cause little more than temporary discomfort.

          You are correct that vitamin is properly considered an immunomodulator, with both immunostimulatory and immunosuppressive effects, depending on the individual’s health status. However, as the authors of this review of vitamin D’s role in autoimmunity conclude, “On the whole, vitamin D confers an immunosuppressive effect.”:

          Thanks for adding to the discussion.


        • Todd,

          This is exactly why Conrad said, “Articles like these do more harm than good.” You are not accurately capturing the current scientific opinion of vitamin D. While it’s fine and good to be skeptical, you need to be evidence-based, and this review is not evidence-based. Here’s where you can learn more about evidence-based medicine: http://www.cebm.net/index.aspx?o=5653

          The increase in fractures is because they used a 500,000 IU mega-dose. We now know that mega-doses 300,000 IU and over superficially increase bone turnover, thus leading to an increase in fractures. Daily dosing does not negatively affect bone turnover, and in fact, meta-analyses show that vitamin D decreases fracture incidence.

          Researchers actually believe vitamin D can help in prostate cancer. Several trials have been completed demonstrating its safety in use for patients with prostate cancer and several trials are underway to see if it helps in treatment. There have been some randomized controlled trials that have shown vitamin D may prevent prostate cancer, too.

          Vitamin D supplementation does not down-regulate synthesis in the skin or decrease conversion of vitamin D to 25(OH)D in the liver (in fact for the latter, it does the opposite).

          Also, it seems like you don’t understand autoimmune diseases very well.

          • fay louise

            brant i want to thank you for hitting one of the many askew nails head on, i couldnt have said it better.

            the lack of knowledge in this article creates fertile ground for conjuring and instilling a fear based herd mentality to thinking,.. this is not a critical thinking work of writing nor is it ‘full of scientific facts’, its a cherry picked trove of misleading information presented with the wide-eyed-honest pretense that it is skeptical, questioning and looking for truth.. i call bullshit when i see it, and this article is ripe.

            the only thing i found interesting was a comment made by tish beram about polymorphism of the vdr gene affecting her cortisol and thyroid hormones.

        • Conrad

          Hi Todd,
          “This is the key point: Low vitamin D levels MAY be a biomarker for other problems. It may be the consequence, rather than the cause…
          IF vitamin D level in the blood is merely a biomarker, a consequence of good or bad health, then adding vitamin D to the diet will not necessarily improve your health.”

          Vitamin D levels do not APPEAR to fall in the biomarker category of being a consequence such as C-Reactive Protein levels.

          We both agree that vitamin D is essential for optimal health. I think we can both agree that there is a difference between major deficiency leading to rickets and lesser prolonged deficiency that may promote long-latency diseases. Essentially we have to get sunlight of an adequate UV intensity for our body to make this. Many people get very little sun exposure and many more cover themselves in UV blocking sunscreen and D is not present in adequate quantitiy in food. So what happens when we don’t get enough? Does our body down-regulate its need for this substance? This sounds like a big MAYBE.

          There are many nutrients that our body can’t make that we have to get from outside sources; various vitamins and minerals, cofactors for creating ATP, essential amino acids, etc. If we don’t get them then we WILL NOT express optimum health. Since many people are not getting adequate UV exposure, supplementation makes sense as the next best thing.
          Research/studies are not all created equal. In fact there are a lot of crap studies out there. Just because it’s in a journal doesn’t mean it’s good science. Here’s a link to a paper that discusses some of the common errors in Vit D research. (Page 6/7) http://www.chineseherbacademy.org/Vitamin_D.pdf

          This is my specific objection to those studies. I didn’t find links to see for myself but it doesn’t even make sense that Vit D would CAUSE and increase in falls nor an increase in fractures considering it’ role in calcium utilization amongst other elements of bone health. http://www.mayoclinicproceedings.org/article/S0025-6196%2811%2962740-7/fulltext

          I respect your time in putting together a lengthy blog post and addressing/citing various research and discussion on this topic. I know that these take a long time.

          • gh

            This is way late I know, but – the increase in fractures would have been because of the calcium to magnesium ratio in their bones being too high because of the vitamin d increasing calcium metabolism. If the women had supplemented magnesium along with the vitamin d there likely would not have been an increase in fractures. The same thing happens in people who drink a lot of milk – too much calcium makes bones more brittle, and magnesium makes them more flexible.

  21. sheilla

    So what do you say about people who are dealing with known autoimmune diseases, ( for me it’s Chronic Lyme disease and under active thyroid). I’m currently under the care of a Naturopathic Physician who monitors my vitamin D levels among many other things. She has me on 4,000 IU’s currently to bring up low Vitamin D levels. Any other suggestions on how to get those levels up without supplementation in the dead of winter.

    • Todd


      I acknowledge that Vitamin D can “help” moderate the effects of autoimmune diseases. No doubt this translates to feeling better in the short term. But it is likely that this is due to an immuno-suppressive effect. You would also feel better by taking a steroid like Prednisone. Just because vitamin D is “natural”, people seem to forget that it is basically a hormone.

      My main point is not to focus so much on achieving a target level of some biomarker like Vitamin D, but to address the root cause of what is causing the autoimmune disorder in the first place. I have some ideas on how to approach that which I hope to address after some additional research.


  22. JM

    my understanding is that vitamin D supplementation is ineffective and perhaps harmful if it is not balanced with vitamin A, K2 and magnesium (and I’m sure we’ll find even more co-factors that are involved in Vitamin D metabolism in the near future since all this vitamin D research has only come out in the past decade) so it does make sense that supplementation is not necessary.
    and yes, correlation does not equal cause…
    thank you for this article.

    • Todd


      Good points.

      I find it interesting that contemporary nutritionists think they have figured out the precise ratios at which vitamins and minerals must be balanced for perfect health, and to avoid harm — as if our metabolisms had not evolved to compensate for the ever-varying ratios that come to us through the food supply, and as modulated by our genetic and environmental variability. It’s like economists who try to micromanage a complex economy.

      Certainly we should be aware of gross deficiencies that endanger our health and bring us close to verifiable health problems such as rickets. I’m aware that vitamin D and other supplements can be helpful. But even if you feel better or address a short term problem by supplementing, that doesn’t mean long term supplementation is advisable. If you are generally healthy, it seems prudent to trust the biology of our bodies over the latest nutritional research and guidelines that seem to change every few years. For how many years exactly have people been supplementing with megadoses of vitamins. How many long term studies are there? And even if we have good data on single nutrients, do we understand the interactions and ratio effects?

      I’m quite healthy, thank you, without taking these supplements. Until I see longer term studies, I trust evolution more than the last 2 decades of nutritional research.


  23. This is a common argument that supplements =/= nutrients from food sources. While I can’t speak on evidence of other nutrients, I can speak that current evidence to date says vitamin D3 is vitamin D3, whether it’s coming from your skin, supplement or a pound of salmon.

    The general idea in supplementing with vitamin D is that few 21st century humans get enough sunlight to make adequate amounts of vitamin D. In fact, studies out of Africa found that Hadzabe and Masaai tribes have 25OHD levels around 45 ng/ml. The average indoor-lifestyle American would need to supplement with 4,000 IU+/day to achieve this level. To me, this is not blindly feeding the body a nutrient. This is a goal oriented practice with a target in mind: to achieve ancestral vitamin D levels.

    While we certainly need more evidence for vitamin D supplementation, for the time being, choosing not to supplement is choosing not to get as much vitamin D as sun-dwellers do. It’s a choice for the individual.

    There are actually quite a few randomized controlled trials showing that vitamin D supplementation is effective for a multitude of things:

    -1,000 IU/day for infants with heart failure improved their heart fraction.
    -Mega-dosing with vitamin D reduced risk of death fivefold for patients with cystic fibrosis vs placebo.
    -Mega-dosing with vitamin D reduced risk of death by two-fold patients admitted to the hospital for traumatic brain injury vs placebo.
    -50,000 IU/week prevented or delayed onset of multiple sclerosis vs placebo.

    These are all serious conditions with patients with serious needs. In these instances, choosing to administer a supplement to them is vital and evidence-based. I implore you to read more about some randomized controlled trials published last year here: http://blog.vitamindcouncil.org/2012/12/18/rct-vitamin-d-levels-and-traumatic-brain-injury/

    Lastly, sun exposure may be choice, for other reasons (it likely regulates a lot of things in the body), but in regards to vitamin D, again, there is poor evidence that sun exposure is better practice than supplementing.


    • Todd


      Thank you for your post. You may be surprised to know that I agree with you on a key point: that supplements like vitamin D can be helpful in acute treatment of people who are very ill. But I haven’t seen evidence that supplementation with vitamin D provides any long term benefits for those of us who are generally in good health.

      Furthermore, why should we care whether or not our measured vitamin D blood levels are lower than those of “ancestral” African tribesmen? By itself, the observation that the Hadzabe and Masaai have higher 25-D levels than do you or me proves nothing. For this to be a meaningful fact, we would need to establish that (a) these tribesmen live longer or are healthier than we are in some important respect; and (b) this is more than a mere association, that is, we would need proof that their higher vitamin D levels causes their good health or is somehow essential for it. It could also be the case that their good health is the cause, not the consequence of their higher vitamin D levels. Correlation does not establish causation, or the direction of causation.

      The randomized controlled studies you cite concern people with major illnesses: infants with heart failure, cystic fibrosis patients, and those with traumatic brain injury. Even assuming some of these ill people benefit, the traumatic brain injury study you linked is not so easy to interpret. The brain injury patients were divided into 3 groups and treated for 3 months:

      Placebo: 15% had “good recovery” (however that is defined)
      Progesterone: 25% had good recovery
      Progesterone + vitamin D: 35% had good recovery

      So vitamin D enhanced the benefits of progesterone. But since there was no “vitamin D only” leg to the study, we don’t know whether vitamin D by itself would have helped. In fact, the study report speculates that vitamin D helped progesterone due to “complementary mechanisms”. And this study was apparently designed to follow up on the observation that “Recent studies have suggested that vitamin D deficiency may worsen traumatic brain injury and reduce the effects of current treatment.” So we are left with a mixed picture about how effective vitamin D is for trauma patients. Sometimes it helps, sometimes it hurts.

      The other thing to point out here is that this study, like the others, was a short term study. You can find numerous studies showing that treatment of conditions with hormones and steroids provide significant benefits in the short term — weeks to months. But we know that the body responds to hormones and steroids by homeostatic compensations, and that sustained administration of these powerful agents can have significant side effects, including elevated risks of cancer and cardiovascular disease. We also know that megadosing vitamin C is very useful in treating acute infection. But long term studies show problems with megadosing vitamin C and other antioxidants. I’ve listed a number of such studies in my article, “The case against antioxidants

      I come back to my main point: For healthy individuals — not those with major illnesses — the case has not been made that long term supplementation is helpful. In fact, I’ve cited several studies in my article indication that vitamin D can be harmful in some cases. It’s not so black and white as advocates of vitamin D supplementation suggest.


  24. I wouldn’t say there isn’t any evidence that supplementation helps long-term health, it’s just the highest standard of evidence – randomized controlled trials – have not been done yet for a large scale population. These kinds of trials cost millions of dollars and are just now underway:

    • In the United States, they’re administering 2000 IU/day or placebo to 20,000 participants.
    • In Finland, 1600 IU/day or 3200 IU/day to 18,000 participants.
    • In New Zealand, 3300 IU/day or placebo to 5,100 participants.
    • In Europe, 2000 IU/day or placebo to 2,150 participants.
    • In the UK, 2000 IU/day or placebo in 20,000 participants.

    Results are coming in 2020. While waiting for the results before you start supplementing is always an option, I’ll offer a hint: they’re studying these doses because they think there is benefit.

    I think you should care about ancestral vitamin D levels because it places the burden of proof on the argument that we don’t need those vitamin D levels. Right now, people calling for higher vitamin D levels/supplementation are asked for proof, when based on what we know, the burden of proof should be placed on the argument that lower levels are fine, when there is poor evidence this is the case.

    Thanks for the breakdown of the randomized controlled trial I posted.

    I actually meant to link to this blog here which flies through the results of 21 randomized controlled trials published in 2012: http://blog.vitamindcouncil.org/2012/12/31/a-look-back-at-2012-a-few-key-randomized-controlled-trials/

  25. David Kipping

    Evidence and arguments that challenge your thesis:

    1. Adapted from http://www.vitamindcouncil.org/news-archive/2008/professor-marshalls-recent-discovery/:
    If low vitamin D levels are the result of disease, then cancer would cause low vitamin D levels, not the other way around. Professor Joanne Lappe directly disproved that theory in a randomized controlled trial when she found that baseline vitamin D levels were strong and independent predictors of who would get cancer in the future. The lower your levels, the higher the risk. Furthermore, increasing baseline levels from 31 to 38 ng/ml (77.5 to 95 nmol/L) reduced incident cancers by more than 60% over a four year period.
    Therefore, remaining vitamin D deficient (below 40 ng/ml) will cause some who are otherwise generally in good health to die from cancer.

    2. For people living outside (sub)tropial regions we know that vitamin D levels follow a seasonal pattern: highest during the end of the summer and lowest towards the end of the winter. Which makes perfect sense as on these latitudes there is no UVB available for the skin to produce vitamin D during fall and winter.
    We also know the flu and common cold bottom in the summer and peak in the winter.
    So whenever vitamin D levels peak -overtly caused by the UVB of the sun- infectious diseases like the flu and common cold bottom. If vitamin D would be mainly immunosuppressive it would be the other way around; causing less resistance during the summer thus more harmful infections.

    • Todd


      Thanks for engaging in the debate. (And for doing so in a straightforward, respectful manner). Let me try to respond to your specific points:

      1. You say “If low vitamin D levels are the result of disease, then cancer would cause low vitamin D levels, not the other way around.” I don’t see how the conclusion here follows from the premise. Low vitamin D might result from diseases that have nothing to do with cancer — say, compromised immunity, infection or other causes. That leaves open the question of whether or not cancer is causally related to vitamin D levels.

      2. I already commented on the Lappe study in my above comment #10 in reply to Nate:

      Critical analysis of Lappe’s data suggest the study was flawed because the control group was not properly randomized, the duration of the study was too short, and the incidence of cancer too low to establish statistical significance:

      3. As you indicate, the increase of vitamin D levels in the summer and in the tropics is exactly what we should expect, since UVB catalyzes vitamin D synthesis in the skin. But the fact that colds and flus are ALSO less frequent in the summer does not by itself prove that this has anything to do with vitamin D levels. It is merely a correlation. There could be countless other seasonal factors (e.g. ability of infectious organisms to spread or thrive) that influence the incidence of respiratory infections. In general, if the incidences of A and B go up and down together, then it is possible that A causes B, that B causes A, that both are separately caused by C, or that it is mere temporal coincidence. June is the most popular month for weddings and graduations, but June graduations don’t (usually) cause June weddings 😉

      4. Let’s suppose that Vitamin D does in fact reduce colds, as you suggest. If so, we cannot rule out that Vitamin D does so by SUPPRESSING immune symptoms in the short term. (Odd as it may seem, immune suppressants like corticosteroids do control infectious symptoms in the short term). But even if naturally elevated vitamin D levels positively stimulates the immune system, that doesn’t mean it is wise to supplement daily and continuously for the long term. Vitamin D is an immunomodulatory compound. Even if it is an effective immunostimulant when moderately elevated for weeks or month, there are examples of other compounds (vitamin C, Echinacea) that become immunosuppresive at elevated doses or when ingested chronically:

      5. Finally, even if chronic vitamin D supplementation is helpful in combatting colds and flus, that doesn’t establishing its advisability as a daily supplement. We would want to look at many possible effects beyond the prevention of cancers and respiratory infections.

      I’m all for using drugs and supplements, even experimentally, to treat short term conditions. But I’m chastened by examples of drugs and even “natural” supplements that demonstrated initially beneficial effects for weeks or even years — but where the downsides took years to show up. Supplementation by estrogen and growth hormone are only two examples of this.

      In my view, the evidence we should demand for long term supplementation by healthy people should meet a much higher standard than what we require for acute treatments of sick people. At the end of the day, this risk threshold is as much a personal judgement as it is a matter of pure science.


  26. Hello,

    I read your post on the CASE AGAINST ANTIOXIDANTS. Happy to have read a thorough analysis representing the “other side” to this debate/issue.

    I agree to what you have said… and the following question popped up:

    What would be the efficacy of taking supplements, antioxidants etc on a sporadic and random basis … As to not disrupt the ARE … and make your body rely on the crutches…

    Would you consider it a waste of money or is there a certain logic to this idea?

    • Todd


      There is something to your suggestion. If you are going to experiment with supplementation, a case can be made to vary the dose and frequency and avoid getting into a pattern of “dependency” that weakens endogenous defenses. But in general, I would avoid supplements except when you have a known health risk or acute issue that needs addressing — for example an infection or allergy that responds to the supplement. And I would take it only as long as you need to.

      If you are healthy, why supplement?

      The exception I would make to this would be foods or compounds that actively stimulate or build immunity or other defenses, e.g. curcumin. These are not “supplements” to address a “deciency”, but rather positive stimuli to defense and repair systems. I’ll have more to say about that shortly.


      • Thank you Todd, I appreciate the individualized responses.

        I guess that the rationale would be to hedge potential risks (like they say in finance)…

        I feel healthy but the following question looms: what if my diet lacks in certain minerals and antioxidants…

        I can eliminate the risks by not supplementing on a constant basis but try to gain the benefits of supplementation if my body needs it… If my body doesn’t need it, it will probably flush it out…

        I realize that the preceding logic is not very thorough and scientific… (on a side note, I follow a paleo/primal/upgraded paleo and realize that diet is the building block to good health…)

      • Ron

        “”If you are healthy, why supplement?””

        This is the problem. I consider myself quite healthy for my age – remember, this is usually an opinion and is very subjective if you think about it; I mean, what IS healthy?.

        A few members of my family swear by taking vitamin c in the winter months to stave off colds/flu. In the not so distant past, I thought it was poppycock – not sure why, just a self-proclaimed belief (ie, no cure for the common cold, blah, blah).

        But then I caught a massive upper respiratory infection, or at least a cold that led to it, about 5 or so years ago. Lingered for a few weeks as I remember. I told myself that I didn’t want to go through that again and ever since then, have been taking the extra C during the depths of winter and haven’t had a cold or flu since. I know, could be coincidence, but it also may not be. This is my problem. How does one really know if taking a supplement is advantageous or not? If I didn’t take it, would I have caught a cold or virus? Who knows; it’s possible. Or… is it possible that I actually caught a virus somewhere in there and the extra supplementation helped my immune system and eradicated it before any symptoms could surface? Or… is it possible that I never even came in contact with a virus in the first place? Again, no way to really know.

        I’m erring towards (what I feel is) the safe side and thinking that the supplementation (including D) is preventing sickness, only during the winter months for now (am in the northeast US). I’ve nothing else to go by for this trial and error study on myself 🙂 I have to believe it’s working.

        Obviously, one could go back and forth on this and have strong arguments on both sides. I don’t necessarily agree with your [theories], Todd, but I don’t disagree either, if that makes any sense.

      • Kiki

        Hello Todd.

        The problem is that if you stop supply yourself with 2000 IU D3 per day, then you will have poor results in your next blood test, less than 20 ng/ml and there you have to start again supplementing, until you reach at least 30 ng/ml. My endocrinologist had suggested that I supplemented with d3, in order to lower the parathormone, and that is what happened. Sunbathing did nothing in my case. I want to stop taking it, but I am afraid of colon cancer, mother had it.
        I have to say that it did nothing to my depression, although I’ve been taken 2000 IU for more than 6 years and I have a constant hair loss during this period.
        Would you be kind enough to tell me if I have to take omega 3 every day of my life and also what do you think about SHAM-e?
        muscle weakness? Tell me about it! TWO YEARS after I started supplementing with D3 I experienced TMJ and I still have this problem.

        • Todd


          How do you know that low vitamin D levels are the cause of your condition, rather than a consequence of it? As you say yourself, supplementing with vitamin D3 did nothing to correct your depression or hair loss. So it seems that you need to look for factors besides vitamin D.

          Rather than pursuing supplements like vitamin D, omega-3 or sam-E, consider changing your diet. Dramatically reduce your intake of sugar and starch carbohydrates to less than 50 grams per day. In particularly, cut out bread, cake and cookies, and sugary soft drinks. Eat no more than a fist size portion of protein per day. And eat more foods with fats and fiber — meats, fish, nuts, cheese, green vegetables, berries (but not fruit). Particularly increase your intake of fats in meats, avocados and nuts, and supplement with coconut oil, butter and olive oil. Eat 3 meals a day, but cut out all snacks between meals.

          Try it for two weeks and let me know how it affects your mood and your hair. This is much more sustainable than taking a lot of supplements.

  27. David Kipping

    Thanks for your quick and long response, Todd!

    Some remarks:

    1. Just read ‘cancer’ where I wrote ‘disease’. Point at issue is whether there is a causal relation between disease and observed low vitamin D levels, not what disease caused it.

    2. ‘But, as one reviewer noted, the reduction in cancer incidence appears to be statistically insignificant. Out of about 1200 women, there were 4 cancers in the supplementation group, versus 7 in the placebo group.‘ Unfortunately, The New York Times article you cited here in reply to Nate was completely mistaken about the numbers. There were 13 cancers in the supplementation group, versus 37 in the placebo group. Here’s the original paper: http://www.grc.com/health/pdf/Vitamin_D_and_calcium_supplementation_reduces_cancer_risk.pdf.
    And here the rebuttals of the researchers to your 2 other cited critical responses to their research:
    They conclude: ‘The concerns of Ojha et al about the validity of our study have no sound basis. The design of our study (population-based, random assignment, double-blind, and placebo-controlled), the low dropout rate, and the excellent compliance with treatment provide confidence that the findings are valid. Furthermore, our findings are supported by a large body of epidemiologic, observational, and case-control evidence that vitamin D decreases cancer risk. Finally, vitamin D supplementation is safe and inexpensive. We argue that it is in the public interest to strongly support optimal vitamin D nutritional status.’

    3. There are many other examples like the winter flu season. Bottom line: there’s a strong trend that whenever there’s plenty of UVB from the sun available, vitamin D levels are up and diseases are down.

    4. To my knowledge this effect has not been reported with vitamin D. As long as you don’t go beyond 50.000 iU a day for many months and keep your level under 100 ng/ml all seems to be completely safe. It’s really hard to poison yourself with vitamin D. Some guy had been poisoned with vitamin D by his girlfriend and got more than 1,6 million iU per day on average. He only got toxic after several months. And survived.

    5. A critical distinction between vitamin D and supplements like estrogen and growth hormone is the natural occurrence. Our ancestors used to live in East Africa near the equator for tens of thousands of years. They likely got between 5.000 to 20.000 iU on average per day resulting in D levels of 40 to 80 ng/ml. That’s how we survived as a species for over 100.000 years; hard to argue with that. Experts agree that vitamin D through the sun is the same as from a supplement. So whenever I can’t get my daily D from the sun I take it from a pill. “Primal” practice facilitated by modern technology. 😉

  28. Phil Moufarrege

    Nature is so complex so that we don’t have to be. “magic miracle pills” to think that we can recreate the power of the sun in a pill is ignorant. We understand less than 5% of plant wholefoods yet we try and isolate parts of them and think “more is better”. there’s a reason why pharmaceutical isolated vitamins cause chaos at a cellular level and why a carrot doesn’t. There’s a reason why the carrot looks and tastes like a carrot and not like a tablet. The entire structure is necessary to deliver the messages to the cells

  29. Tish Beram

    Great article!! I have had a DNA test due to having autoimmune thyroid disease. My doctor was suspicious & his suspicions were confirmed, I have a polymorphism of my vit D receptor gene. Yes my D levels were low, but after about 6 or so months of taking vit D, it started to raise my cortisol too high & to either suppress my thyroid hormones or sending me extremely hyperthyroid. It makes me very tired too. My dr has quite a few patients with this genetic issue. The problem is majority of dr’s are unaware this condition exists & people are self dosing without being tested & if they have a reaction, their dr would never suspect vit D could be the culprit. I also have the MTHFR gene mutation which means regular folic acid, normally found in vit B’s, is a no no as my system doesn’t know how to convert it. I believe a lot of the popullation have this issue, but wouldn’t know it. Sometimes vitamins are just bad news for some of us sadly.

    • rita

      Hi Tish,

      I have been diagnosed with the polymorphism of the vit D receptor gene.

      I was hoping talk with you to discuss it; I am a medical librarian and I thought it was a rare condition brought on by having chemo.

      If you read this comment I would like to communicate with you if possible by email or phone. My email is ritahsher@gmail.com and 301 617 0658 if you are interested.
      Rita Sherman

  30. Jeff


    It sounds like you would have similar thoughts on supplementing thyroid for people who are diagnosed hypothyroid. Its hard to deny the results, Broda Barnes and other doctors who treated patients showing signs of low metabolism (lower pulse and body temperature)with supplemental thyroid. I believe Barnes has stated not one of his patients had a heart attack who was on supp thyroid. I could be wrong but still his results are hard to argue with. Also,in the case with megadosing supplemental thyroid the gland does return to normal in just a few days after stopping the mega doses, per Ray Peat. Probably would be the same in the case of overdosing Vitamin D? I subscribe to the high metabolism theory of good health as Ive noticed I feel the best when my temp is 98.6 or higher and my pulse is around 85 beats per minute. When temps and pulse rate drops so does my state of health in terms of how I feel. If thyroid supps and vitamin (A,D, K, etc) supplementation is required in addition to a nutritious diet to sustain these markers so be it. Ill take my chances and put my money on keeping my body in a state of high metabolism and low stress over worrying that the supplement might be doing other harm.

    • Todd


      I’m not opposed to to supplementation under all circumstances. As I mentioned in the article, if you have an illness (like Hashimoto’s disease or hypothyroidism), or an acute condition like an infection, then supplementation with vitamin D, other vitamins, or even hormones, can help and may in fact be required. There is no doubt that supplementing with vitamin D or thyroid hormones will cause levels to return to a normal range. But why is our instinct always to treat the symptom rather than the cause — particularly in the case of chronic conditions? When we treat symptoms rather than causes, we often risk provoking homeostatic compensations.

      Ask yourself what causes hypothyroidism in the first place. Hashimoto’s thyroiditis is considered the most common cause in the U.S. The precises causes are unknown, but it is an inflammatory condition and an autoimmune disorder:


      But low thyroid function is not always responsive to thyroid hormone. Chris Kresser explains why in this interesting 5-part series on hypothyroidism and low T3 disease. He points out that taking thryoid hormone is not always the best idea:



  31. Judith Hodges

    I just discontinued the daily dosage of 5000IU D3 and I did so after reading about the signs of overdose and so many subtle but increasing side effects that I did not realize were connected to D3. I feel so much better – and it never really made sense. I agree with your articles.

    It makes no common sense to take D3 when it is a process that the body was designed to do itself. Came to the conclusions that the testing is showing something other than a deficiency of D3 as well. What a bunch of chattering squirrels in trees. I prefer to respect Mother Nature and learn to listen. I’m just mad that I did not listen to my own concern when D3 was recommended 3 years ago.

    • Ron


      Can you elaborate on what the “subtle but increasing side effects” were? Just curious.


  32. Paul

    I think the research you present to counter the Vitamin D supplementation argument is flawed.

    “A 2010 double-blind, placebo-controlled study, published in the Journal of the American Medical Association, found that older women who received annual oral high-dose vitamin D had an increased risk for falls and fractures.”

    These women took high doses ANNUALLY. E.g. once a year. So in one month their body gets a huge vitamin D shock, and then for the rest of the year, nothing. It depends on when they took it (summer or winter), how much they took and whether they got any sunshine outside of the supplementation. So many variables.

    I also think it’s possible to OVER analyse something. Whilst I am impressed with your level of detail, I can’t help conjuring up images of how the human race evolved over thousands and thousands of years.

    In Africa. In the sun. Without clothes.

    When man migrated away from the equator, he lost the dark skin because lighter skin is better for getting vitamin d. Dark skin is not so good. Ancient tribes did not ‘pop a pill’.

    It’s the mad crazy modern world that’s killing us. Sweets, candy, crisps, chips, sugar pop drinks, cigarettes, booze, drugs and television and trains and cars and petrol. That’s what’s killing us!!

  33. “In fact the two above-cited studies on the effects of supplementation on bone fractures in older women, and prostrate cancer in older men are two such interventional studies. And they showed that vitamin D supplementation was harmful in both cases.”

    Except that in the first study the women had more trouble because they felt better, got moving outside and had not built their muscles up completely before doing so and fell more than the controls on their couches. This was what the researchers said.

    The second study used groups randomly selected from another study and if you looked at the description, the Vitamin D supplemented group was older, had more diabetes and more cardiovascular disease (and that is why they were taking the D.) The so called control group was not matched for age or condition. So was the mortality due to the Vitamin D or because they were older and sicker.

  34. hlahore

    VITAMIN D is NOT just correlation.
    Vitamin D has been proven to reduces 29 health problems
    Vitamin D intervention with placebo control for the following:
    Hypertension, Cardiovascular, Back Pain, Diabetes, Influenza, Falls, Hip Fractures, Breast Cancer, Raynaud’s pain, Menstrual Pain, C-section and pregnancy risks, Low Birth Weight, Chronic Kidney Disease,
    Cystic Fibrosis, Rheumatoid Arthritis, TB, Rickets, Respiratory Tract Infection, Lupus, Sickle Cell pain,leg ulcers, traumatic brain injury. Parkinson’s Disease, Multiple Sclerosis, Congestive Heart Failure, Middle Ear Infection,Gingivitis

    Details at http://is.gd/proofvitd

    • Todd


      Vitamin D Wiki is an interesting site, but it is a product of the Vitamin D council, so it certainly cannot profess neutrality. These are folks whose livelihood is based on a cheery message for vitamin D. The title of the page you linked is “Proof that vitamin D works”. There is no similar page provided for contrary evidence.

      I checked the “interventional” studies for some of the conditions you mention. Under “hypertension” they link to the following list of studies, which turn out to be observational, not interventional:


      Here is the link to the page that lists actual intervention clinical trials. Note that they are said to be still “in progress”:


      There is one page referencing the Women’s Health Initiative Study, the largest ever randomized controlled trial studying the effects of vitamin D and calcium supplements in women. The study itself gave negative results, but the Vitamin D Wiki page tries to salvage it by re-analysis, breaking out various subgroups. That’s all well, but this sounds like folks looking for the silver lining

      Here is what the actual investigators themselves concluded


      Supplementation effects were not apparent on the risks of myocardial infarction, coronary heart disease, total heart disease, stroke, overall cardiovascular disease, colorectal cancer, or total mortality, while evidence for a reduction in breast cancer risk and total invasive cancer risk among calcium plus vitamin D users was only suggestive. Though based primarily on a subset analysis, long-term use of calcium and vitamin D appears to confer a reduction that may be substantial in the risk of hip fracture among postmenopausal women. Other health benefits and risks of supplementation at doses considered, including an elevation in urinary tract stone formation, appear to be modest and approximately balanced.

      Note that the author’s themselves did a subset analysis and found the benefits of vitamin D + calcium for cancer to be “only suggestive”, i.e. not statistically robust. And this is cherry picked out of all the other conditions studied. Statiscally, you would expect that perhaps 1 out of 7 conditions studied might show a positive outcome.

      If you can point to an actual condition showing a benefit from an interventional RCT (or ideally meta analysis), I’d love to see it.



      • Heidi

        The Women’s Health Initiative Study allowed placebo group to take vitamin D, and the treatment group was taking MINISCULE doses of vitamin D. The study was all kinds of flawed design, and accounts for almost 80% of the weight in the Lancet publication.

        • Todd


          You may be right that the WHI study was flawed. As you point out, the study design has been criticized, e.g.:

          I’m still looking for an interventional study with clear cut benefits of vitamin D supplementation without long term downsides. Here is a follow up WHI study, just published, that does indeed show a reduction in hip fraction in women taking vitamin D plus calcium, but with the addition of hormone replacement therapy. So yes, there is a benefit when estrogen and progesterone are added to the mix.


          But we also know there are risks that come along with hormone replacement therapy. Is the risk worth it? That’s an individual choice, which I respect. But if it were me, I’d pursue less risky approaches, such as adding weight bearing exercise, along with diet ample in minerals and fat-soluble vitamins, rather than play roulette with supplementation of hormones and hormonally active supplements.


  35. John

    I don’t fully understand the biological aspects of how vitamin D pills are processed differently from the hormones produced naturally from sunlight, but my doctor recommended vitamin D3 pills and I take 3 of 1000 iu everyday… mostly. I think I understand your concern about how we make our bodies more dependent on the pills and invite possible side effects, but by that logic… when we get old and not use vitamin D pills, wouldn’t the skin use homeostasis to produce more vitamin D hormones? I guess the skin would be less effective through aging, but I should be more free to get out by the time I retire… or close to it anyway. I tend to stay indoors a lot; juggling with school and work doesn’t let you get out as much as I’d like.

  36. charlie

    Very interesting. I have just been told by my doctor to take vitamin d supplements as my blood test showed low levels. I have rhumatoid arthritis and am on immune suppresant drugs at the moment. Does anyone think that these things are related as I have had vit d difficiency symptoms for over a year and have been ignored by all my doctors! Also since begining my drugs I have stopped tanning, I have always been fair but used to go very brown in summer etc. I now never tan, no matter how much time I spend outside. This doesnt bother me but it has intrigued me and noone could explain why. Any ideas?!?

  37. Jim

    Hi, I have been scouring the internet trying to find info about the issues Im having. Im down to researching if my 4 years of vitamin D3 supplementation is causing some of this. The short of it is:

    Somewhere around 2008 or so I started taking 5000 IU of D to help with depression.

    9/13 – tapered slowly off of Lexapro for the 3rd time.

    12/13 – experiencing morning fatigue, heavy legs, waking up for and hour or two at night.

    1/14 – Took supplement Seriphos to lower my cortisol – it destroyed my sleep – no sleep.

    2/14 – discovered that vitamin c helped me sleep but I would wake up the next morning agitated and anxious. Lowered the dosage repeatedly with the same problem. Theory is that it is stimulating my adrenals to produce ? Then it is easily flushed away.

    -Within 2-3 I am now unable to even eat food with vitamin C in it without getting very anxious and agitated.

    -Consulted a Naturopath about adrenal fatigue – getting a salivary cortisol test – waiting on results.

    -Completely dumbfounded. Afraid to stop D cold turkey fearing some insane withdrawal?

    Any insight on what the heck is going on? Going to GP today to request test… testing what I have no idea.

    • Todd


      Many of the symptoms you describe (fatigue, insomnia, agitation) are not uncommon side effects of discontinuing antidepressants:

      Vitamin D can sometimes deplete magnesium, and low magnesium can cause anxiety and fatigue:

      Have you considered supplementing with magnesium, before discontinuing the vitamin D?

      • Jim

        Hi Todd, thanks for your response.
        Right now I am stuck on whether this is SSRI withdrawal or Adrenal Fatigue. I have been cautioned to not mess with my adrenals if its ssri withdrawal so I am just eating very carefully, and trying to sleep. I have talked with a naturopath about adrenal fatigue but I am not excited about trying a bunch of supplements or paying for it all.
        I had no trouble tapering very slowly from the drug, the issues began a month or so after getting off of it.

        I have used magnesium oil off and on.

        • Todd


          I think you are wise to be cautious about supplementation. It’s always a double-edged sword. Have you considered eating a balanced Paleo type diet, with ample fats, protein and greens, while reducing sugars, easily digested starches, and omega 6 vegetable oils? Many with adrenal fatigue have found that to be their ticket back to health.


          • Jill

            Hi Todd
            I’m 39 and unexplained infertility, I’ve read about corelation between D3 deficiency and infertility. Blood test for 25OH shows 5.77, and I said…I’ll take D3 supliments(800UI/day)
            All I can say after 10 days is that I’m not ovulating, and I should days ago, I think my estrogen level is too low to do it, I feel strange things in my legs(I have L4-L5 back surgery, 4 years ago, I was fine untill now); bottom line, I don’t like at all those “bennefits” and I really think to stop taking those pills
            Thank you for your interesting article.

            • Todd


              The question to ask is whether your low vitamin D status is a CAUSE or rather a CONSEQUENCE of the infertility and low estrogen levels. If it is the latter, then supplementing with vitamin D won’t necessarily help; you need to get to the root cause of the infertility. Here is a website that lists many different possible causes, including PCOS and certain inflammatory conditions:



  38. Bruce

    Todd, I really enjoyed your discussion on “Why I don’t take vitamin D supplements”. Great information and I loved the graph showing storage vs. active form Vit. D. Well documented, and are asking some good questions. I’m in a Facebook group discussing the benefits of magnesium. We would like to refer to your article and copy the graph of storage vs. active Vit D. Do we have permission? We generally are in agreement with your article, but it may be difficult to ‘prove’ everything, not our objective. We just want to ask (as you have), is Vit D supplementation really necessary.

    Also, has there been any new information on this since you posted this article?

    Look forward to your feedback, Bruce Johnson

    • Todd

      Hi Bruce,

      Glad to hear you found the article instructive. Fee free to link or refer to my article. The figure you mention is from “Second guessing the consensus on Vitamin D” by Paul Albert and Amy Proal. I provided a hyperlink to the article above (linked to the phrase “As the authors note”), or just click here:


      I don’t have any updates to provide on vitamin D studies, but I’m most interested in interventional trials.


  39. lisa

    Interesting article! One thing to note: 7-dehydroxycholesterol in a provitamin of D3. It has to be converted to to D3 and then converted to an active form just like D2 and D3.

  40. rosa

    love this article, except for one thing, I am just now starting to realize (better late then never I guess)that we have been so ingrained with fear of vitamins and minerals I mean when is vitamins and minerals so dangerous we have to be warned against them while drugs are given a free pass? frankly I don’t make vitad3 from the sun, I have to supplement, I spent years trying to eat healthy, eating lots of fruits veggies whole grains lean meats avoiding through sheer willpower the junkier foods. I have sun bathed until I am baked t death figuratively without using sunscreen and my symptoms never got better only worse (metabolic syndrome galoire and all the misery that comes with it in the advanced form short of full blown type 2. I have done low calorie diets the most, but low carb low fat exercise regimen you name it supplements for glucose tolerance improvement, you name it I probably tried it. never could stick to it and my sympotms never got better. now I have been experimenting with vitad3 supplements the wool oil over the past 1 and a half. my symptoms are abating, (to long to list could fill several posts)I did several different dosing, and for me I cannot go lower than 20,000 iu a day otherwise after a few weeks my symptoms come back. I am sleeping better my apptite is normalizing, my energy levels are going up (anyone who knows me I am a sluggish as a argentinasaurus (dinosaur) and slow and fatiguing as a turtle. I was always getting sinus infections, bronchitis for many years, I was constantly going to the doctor for one thing or another. being obese is probably why I have to take such high doses vitad3 is sequested in fat cells. once they are full however it leaves more for other function, if your glucose intolerance, obese, hypertension galore, sluggish, get little results from exercise cannot stick to a healthy diet cannot sleep through the night without having to get up and eat (nervousness and hunger really was a problem at night)cant stick to a diet must constantly munch or get nervous and irriatable and wired and tired, and not able to sleep soundly, if you do not feel like doing anything, still take regular vita like a multiple vitamin without d, a or k, and many supplements do not improve your condtion then vitad3 might just be the ticket. I know it sounds simplistic but it is working for me, and it has been a very pleasant surprise. I have battled metabolic syndrome since I was 10 years old it is now 40 years later and finally I am starting to grasp what my problem was. in fact I was so sickly for so long I thought I would just die one day, and at the time I was thinking I wish I would as I was so miserable. doctors were no help. except to tell me to lose weight, well duh what do you think I have been trying to do for 40 years. I was constantly battling anxiety attacks and headaches and foggy thinking, and this was just the tip. by the way the illness that you suffer from after improving diet for diet or supplements including vitamins are probably healing crisis, I found if I supplement really heavy with vita c, some bs, minerals like zinc and magnesium along with the healthier diet the healing crisis is bufferd and shorter in duration (before it was like 2 weeks at a time) now I am feeling so much better it has taken me fourty years fo suffering experimenting and observation, research to come to the conclusions I have about heatlh, vitality and quality of life and understanding survival mechnisms of our bodies. well mine anyway.

  41. Rachelle

    I’m not claiming to be a expert or anything ….I do have some medical training my understanding is anything can be dangerous or cause imbalance if not taken with cofactors….could this be an issue with the ” bad” reactions….I know myself, I have bad reactions to d , ie joint point, when I don’t supplement, vitamin a, manganese, k2 , magnesium…I’m sure there’s more…..I figure with the increased intestinal calcium absorption mitigated by d3 the body needs these cofactors to tell it what to do with the calcium….instead if putting it in soft tissue areas……in the end it seems that there is not a genuine replacement for adequate sunshine…and the body self regulating vitamin d…..it is sunshine that produces d-sulfate and cholesterol sulfate….although I do believe some d3 supplementation can help…..

    In the end it seems playing with any supplement will make it where you end up doing countless research on cofactors and other supplements as different things pop up that constitute probable deficiencies…..considering how lacking the soil is in nutirients and therefore produce what is one to do….you could eat all the produce in the world and if the soil it was grown in is lacking then the fruit or vegetable is as well….how are you to know other than possibly cultivating your own soil and growing your own produce…..playing god with supplements seems to be one viable alternative although it creates quite a maze…..

  42. Heidi

    VDR doesn’t convert 25 OHD to calcitriol, CYP27B1 does. This makes all the difference, and your argument entries wrong.

    • Todd


      I never said that the VDR is responsible for conversion of calcidiol to calcitriol. Show me where I said or implied that. My point is that excessive levels of calcidiol have the potential to inhibit or down regulate the VDR and thereby impair its beneficial functions.


      • Heidi

        With all due respect, you imply that the VDR is the important factor here, when indeed almost all cell types convert to calcitriol on an as needed basis using CYP27b1. You mentioned the kidney only. I’m curious, have you ever checked your 25 hydroxyvitamin D concentration? By the way, I’ve supplemented with vitamin D for almost a decade, and honestly, I feel so much better that I wouldn’t be without it. And it’s nothing like prednisone.

        • Todd


          You are correct that the VDR is ubiquitous in most cells, not just the kidney. And yes, I do agree that the VDR plays an important regulatory function, indeed an essential one. But I didn’t say that it is the agent that converts calcidiol to calcitriol. I didn’t know about CYP27b1 before you mentioned it, and I’ll take your word for that. I’m still not sure on how the existence of CYP27b1 somehow undermines my argument.

          My doctor measured my 25-D levels in 2009 at 24 ng/mL. Despite absolutely no health problems or symptoms, he was concerned that this was low and had me start supplementing daily. A year later, my 25-D levels had increased to 52 ng/mL. This is supposedly consistent with improved health. But I noticed absolutely nothing, and there was no objective or subjective change in my health. Just a raised level of 25-D. I subsequently stopped taking vitamin D because I found no reason to do so, and my levels dropped back down to about the original level. Again, with no noticeable effects.

          I’m glad that you have found that supplementation with vitamin D makes you feel better. Perhaps it is indeed improving your health objectively. I’d be interested to know the symptoms you were having that have now disappeared. But how do you know that it is not having a palliative effect, rather than objectively improving your underlying health? Vitamin D may not be as strong or dangerous as predisone, but it can’t be denied that it has hormonal action. Such changes can provide a short term benefit — both subjective and objective — while still posing long term risks.

          My point is not that vitamin D supplementation is “bad” or always wrong. The point is much more subtle than that. I’m trying to urge caution and prudence here. We tend to get onto bandwagons — certain supplements or dietary factors are touted as “good” or “bad”. I’ve lived long enough to see the enthusiasms build up and come crashing down. If your research and personal experience lead you to believe that the benefits of vitamin D or any other supplement outweigh the risks — then go for it. But don’t be blind to the potential risks, particularly as you increase the dosages and frequency of supplementation.

          What particularly bothers me is when the medical profession or health practitioners recommend daily supplementation of something for the rest of your life — even for people, like me, who are objectively healthy and happy by all measures — except for a “biomarker” that is judged to be out of range, where the judgement is based on studies showing correlation and not causation.

          Glad to have your comments, Heidi. I welcome challenges to my thinking, and new evidence. If the evidence for vitamin D supplementation becomes strong enough, I’m willing to change my position. I’m just not there yet.


          • Heidi

            Todd, I do respect your decision to not supplement. Have you read the data on vitamin D supplements during pregnancy which reduce preterm labor and infection? There are several now. Also, the resurgence of rickets is quite frightening. This is simply due to lack of substrate. Humans weren’t meant to live on 400 iu per day, and most get little input from sun. There is good autoimmune data as well. Check out Coimbra’s work coming out of Brazil. I don’t expect to see well designed clinical trials that are large in my lifetime. No one is paying for them. I am conducting a research trial with heart failure and vitamin d supplements. While it is not large, it is well designed. Stay tuned, preliminary data looks great.


          • Heidi


            I tried to reply with my PC but was unable, so I apologize for truncated response.

            I have seen in my own practice on hundreds of patients the effects of vitamin D deficiency. The sad part is that most of them think they are getting a lot from milk and end up with a 25 OHD level of 5 ng/ml. My point about the enzyme Cyp27B1 is that almost all cell types have it.

            As Americans continue to grow in BMI, they have more cells and require more vitamin D. Yet input continues to decrease as people work inside during meaningful UVB hours and slather on suncsreen. Whether or not VDR is upregulated seems much less a component than the onsight conversion of calcitriol in cells, and some cells require a lot. the VDR simply is a gatekeeper. Many checks and balances exist, including the cyp24 which breaks calcitriol down intracellularly.

            I had no specific health problems myself. My blood level was 29 about 10 yrs ago, and at that point started 10,000 iu per day. Within a week I felt my exercise tolerance go up a lot, and prior to that thought my muscles were sore just because I was getting old! I also stopped catching every virus that was floating around. And these benefits remain 10 years later. I’m not saying everyone should take this dose or that it helps everyone physically. What I am saying is that input of D3 is suboptimal in essentially everyone I meet if they are not supplementing.

            Are you familiar with Coimbra’s work in Brazil? Great info on autoimmune dz. Also, great data coming out on pregnancy outcomes with supplementation of higher doses. Multiple sclerosis, psoriasis, some small studies but highly significant results. My colleagues and I are conducting a heart failure and vitamin d study, and good preliminary results. Small but well designed.

            While I agree we all shouldn’t irresponsibly supplement, deficiency really is problematic. Substrate does not appear in blood until 25 OHD reaches 40 ng/ml or more. This suggests to me that cells starve for it anything under this level. Also, Pth doesn’t optimize until 25 OHD is 40 ng or more. I won’t wait for large trials to tell me what to do; no one is paying for them, not well designed ones anyways.

            Thanks for listening!


  43. Sid

    I was fascinated by reading all the vitamin d3 supplement hype, So ended up taking 5000iu. It felt great the 1st month with lots of energy and motivation, a dopamine increase i presume. However party ended soon, 2nd month i fainted 4 times , panic/anxiety attacks, mood swings and then on 3rd month i got vitiligo, an auto immune skin disorder, i swore that day never will i ever take a pill again.

  44. Mary

    Great info and discussions! I have been ambivalent about my vitamin D supplementation for the past year. I have hypothyroidism (no antibodies) and have tested low for vitamin D several times. I’m taking Armour. I’m concerned because I have some thyroid nodules and one was showing some calcification last time I was scanned. I know that D affects calcium and I’ve also heard that it’s best taken with vitamin K2 to offset that. I eat mostly whole foods so I assume I may be getting enough K2 from my diet but I have no way of knowing.

    On top of all that confusion, I have a VDR Taq mutation? No idea what that means. I’m thinking that I will reduce supplementation until I figure out if it’s helping or harming. Thanks for the info!


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