Low-calorie longevity: the anti-aging diet

Better Nutrition, Dec, 2002 by Michael Downey

Want to live longer? How does 120 or more sound? That's realistic, say many anti-aging researchers. But at present, you'd have to switch to what longevity researchers call a "calorie-restricted" diet.

It sounds like dieting, but it isn't. Dieting has the short-term goal of weight loss. But caloric restriction--or CR--represents a lifelong approach to food consumption.

CR, however, doesn't mean starvation. In fact, the objective is to consume fewer calories without sacrificing nutrition.

Through good food choices and supplements, a CR diet is fortified generously with vitamins, minerals and antioxidants to provide the same nutrients as an unrestricted diet--but with substantially fewer calories.

While calorie restriction sounds, well, restrictive, scientists say it's more aptly called the "anti-aging" diet or the "high/low" diet--high in good nutrients, low in bad. That's why half-starved people in famine areas derive no longevity benefit: their low-calorie intake lacks nutrient density.

Caloric restriction isn't a new idea. Since the first experiment in 1935 at Cornell University, in Ithaca, New York, researchers have collected over 2,000 studies concluding that CR can extend animal lives drastically and delay the onset of age-related illnesses. And according to US government scientists writing in the mid-1999 edition of the Journal of Nutrition, Health and Aging, "The well-known effects of CR on lifespan, disease and aging processes may be generalizable to all species."

In fact, caloric restriction is the only strategy to date that has been scientifically proven to extend the "maximum life span"--the term for the technical limit to life, different in each species.

In humans, the maximum life span runs about 110-120 years. You can inherit great genes, eat well, exercise and always buckle your seat belt, but you just can't rise above that ceiling. Or at least you can't without a CR diet.

CR's effects go beyond longevity. Mental and physical abilities, blood pressure and essentially all physiologic parameters of animals on CR diets match those of chronologically much, much younger creatures.

In the April 1996 issue of the Proceedings of the National Academy of Sciences, one animal study concluded CR produces "increased longevity, reduced pathology and maintenance of physiological function in a more youthful state."

In essence, scientists believe that the CR diet actually slows down the process of aging--extending both youth and life span--although the exact mechanism is not yet clear.

mounting evidence

Biogerontologist and prominent CR researcher Roy Walford, MD, is a University of California, Los Angeles professor of pathology who has researched the physiological predictors of longevity for 30 years. He describes CR in his many books, including Beyond the 120-Year Diet. In the 1999 PBS series Stealing Time, Walford says, "Studies I've done on humans secluded for two years inside Biosphere 2 show quite clearly that the extensive physiologic and biochemical changes seen in CR rodents are also found in CR primates--including humans." He adds, "CR works across the animal kingdom, so it would be surprising if it didn't work in humans."

Okinawa, Japan, constitutes a living example. Okinawans have the world's longest average life span--and eat 40 percent fewer calories than Americans and 17 percent fewer than the average Japanese citizen.

Recently, the National Institute of Aging's George Roth, PhD, and colleagues concluded that the same biological markers produced in CR animals are evident in the men who are living longest in a continuing study in Baltimore on aging. These predictive "bio-markers" include lower levels of blood glucose and insulin, reduced body temperature, less fat in the blood, more high-density lipoprotein--HDL, the good cholesterol--and a steady level of dehydroepiandrosterone (DHEA), a steroid hormone.

"This means that the biological characteristics of animals on CR diets seem to apply to longevity in people," says Roth, who coauthored the study in the August 2, 2002 issue of Science.

starving?

Of course, those not fond of nouvelle cuisine will want to know just how many years a CR diet will add to their lives. "Calorie restriction has extended the 39-month maximum life span of mice to an impressive 56 months, which corresponds proportionally to a 158-year-old human," says Walford. Science, it seems, has found the first authentic fountain of youth.

Still, most people may simply refuse to eat less--even if it means they will live to 120 or more--holding out for a miracle "CR drug." The May 24, 2002 Journal of Biological Chemistry reports that genetic manipulations can create the same effect as calorie restriction. The study's author, Harvard University researcher David Sinclair, PhD, says, "What we really want to do is to be able to mimic calorie restriction without having to starve ourselves."

Researchers say an actual CR drug, including potential side effects, may be a long way off. You must decide if you can really afford to wait--aging all the while.