Age Wave: Science Behind Living Longer -- Research Summary

ABOUT SIRTUINS: Sirtuins are a family of genes that scientists discovered in yeast that can make cells live longer. Their significance? "We believe that keeping these genes functioning properly can forestall aging -- it can slow down aging," Lenny Guarente, a biologist at Massachusetts Institute of Technolgoy in Boston, Mass., told Ivanhoe. "The trick will be figuring out exactly how to do that." Sirtuins -- which turn out to be present in all living organisms -- can detect energy reserves in a cell and are activated when those reserves are low, such as when someone eats a calorie-restricted diet. Scientists argue that drugs to activate sirtuins could offer the same lifespan extending benefits as a calorie-restricted diet.

RESVERATROL: WONDER-DRUG OR HYPE? One chemical that has been shown to activate sirtuins is resveratrol, which is a compound naturally found in grapes, red wine, peanuts and some berries. The compound sparked interest in the supplement industry and is already marketed over the counter as a dietary supplement. A drug formulation of resveratrol is in clinical trials as a treatment for type 2 diabetes and cancers. While it has shown promise in animals, long-term studies have not yet been conducted in humans using resveratrol, and some experts caution that dosages of the supplement vary widely. "The problem with taking the supplement instead of the berries is you have no idea how much resveratrol you're getting in the pill," Susan Hewlings, Ph.D., R.D., assistant professor of medicine at the UCF College of Medicine in Orlando, Fla., told Ivanhoe. "You can get the same benefit -- which are antioxidant properties and heart protective properties -- by consuming berries and the dark red grapes."

LESS CALORIES, LONGER LIFE? Decades of animal studies have shown that semi-starvation can extend lifespan by up to 50 percent. Last July, researchers at the University of Wisconsin found calorie restriction extended the lives of rhesus monkeys by reducing the incidence of diabetes, heart disease and cancer. Scientists suggest that in order to add to longevity, a calorie-restricted diet should be defined as one with 25 to 30 percent fewer calories but still containing essential nutrients.

A nationwide, multi-center study is underway to determine of such a diet can extend human lifespan. Called the Comprehensive Assessment of Long-Term Effects of Reducing Intake of Energy (CALERIE) study, participants will be on a restricted calorie diet for two years. Their diet restriction of 25 percent is based on their resting metabolic rate, or the number of calories each person burns in one day. So far, most participants reduced their body mass by about 15 percent in the first year.

FOR MORE INFORMATION, PLEASE CONTACT:
Dr. Lenny Guarente
leng@mit.edu