So you want to live a long life, or at least age gracefully?
Bill Gifford has provided a well-researched and engrossing account of the quest for longevity. In his new book, Spring Chicken, Gifford critically examines the claims of scientists, enthusiasts and hucksters in their attempts to extend life using hormone replacement therapy, telomerase, supplements, drugs, exercise, caloric restriction, intermittent fasting and other practices. Along the way, he visits with a 108-year old investment advisor and a 76-year old female sprinter who can run a 6:58 mile, and he takes a close look at mice, monkeys and microbes that live much longer than species norms.
I found the book hard to put down. That’s not merely because Bill’s hilarious account of my wintry swim with him in the Pacific Ocean appears in Chapter 12–as a bracing illustration of how hormesis builds stress tolerance. I was captivated by reading of his up-close encounters with a diverse set of gerontologists, centenarians and odd, long-lived creatures such as the naked mole rat. Most interesting of all was his meticulous detective work in probing the major competing theories of aging, leading to some unconventional conclusions about what may or may not actually help prolong life and healthspan.
Posted 23 May 2010 — by Todd
One of the first scientifically rigorous demonstrations of the benefits of hormesis was a 1934 study of calorie restriction (often abbreviated “CR”) in laboratory rats, conducted by Mary Crowell and Clive McCay at Cornell. They found that reducing the calories of rats by 30-50%, supplemented with adequate micro-nutrients, could almost double their lifespans. Later studies found continued lifetime extension with calorie restriction up to 65%. In addition, the rats remained energetic and youthful in appearance, with greatly reduced incidence, and delayed onset, of age-related diseases. This same phenomenon has been observed in a variety of other animals.
Studies on calorie restriction in primates or humans are as yet inconclusive. Controlled primate studies only started in the late 1980s and have yet to be completed, although the preliminary indications are very promising. And in humans it is more difficult to conduct controlled studies for both ethical and compliance reasons. An additional factor to consider is that animals raised post-weaning on calorie restricted diets typically have much smaller adult body sizes that animals not restricted in their eating. Because of the social and physical implications of this consequence, advocates of calorie restricted diets for humans advise that they be started only upon reaching adulthood.
Whether or not a restricted calorie diet extends the human lifespan, the evidence is becoming overwhelming that a nutritionally complete diet with reduced calories has the potential to greatly improve our health, particularly as we age. But is it practical and possible for humans to happily adhere to such a diet?