Deborah Kotz

As much as we'd all like to find that fountain of youth, how many people would dive in if it meant eating a lot less -- cutting, say, 600 calories a day from a 2,000-calorie diet?

A new study published in the journal Science may tempt many folks to try such an approach:

University of Wisconsin researchers found that feeding rhesus monkeys 30 percent fewer calories over a 20-year period seemed to slow down the aging process, protecting them from age-related illnesses like diabetes, cancer, and heart disease.

Animals fed less "appear to be biologically younger than the normally fed animals," the study authors wrote.

Only 13 percent of the monkeys on a calorie-restricted diet died from an age-related illness over the period compared with 37 percent of the monkeys in the control group.

"The data are tantalizing," says David Finkelstein, director of the metabolic regulation program at the National Institute on Aging, who reviewed the study.

But, he adds, the findings need to be replicated in the human trials that are currently underway. Another new study out this week found that the antibiotic rapamycin extended the life span of mice: Again, it's not known if this is safe or effective for humans. Certainly, though, researchers are coming to believe more and more that there's plenty you can do now to foil the aging process. "We have a much greater understanding of aging mechanisms," says Dean Ornish, professor of medicine at the University of California-San Francisco, "to the extent that we know which changes help you live longer but, more important, age better."

How well you age depends on the intricate interplay between your genes and your lifestyle, which determines how quickly your cells divide, repair breakages in DNA, and die. Your chronological age doesn't necessarily correlate with how old your body thinks it is, says Michael Roizen, chair of the Cleveland Clinic's Wellness Institute and coauthor of YOU: Staying Young. "There are about 191 things that go into calculating your real age," he says, "and 149 of those things are within your control to change." You can, for example, quit smoking, cultivate strong social support, get regular exercise, and eat right.

Even if you've been slipping up until now, making healthful changes today can turn back the clock--or at least slow it down. Ornish's research has found that a low-fat diet, regular exercise, and relaxation techniques all work in synergy to increase levels of telomerase, an enzyme thought to slow cellular aging and prevent healthy cells from turning cancerous. Specifically, he found that telomerase was boosted by 30 percent in prostate cancer patients who followed a plant-based, whole-grain diet with very little fat or sugar for three months. The men also took fish oil supplements, did daily 30-minute bouts of exercise, and practiced yoga or meditation for an hour a day. "Telomerase turns up those genes associated with disease prevention and turns down the genes associated with heart disease, diabetes, and cancer," explains Ornish.

The "pound of cure" lifestyle approach examined in his study may not be necessary for healthier folks, he says.

They may need only an ounce of prevention to maintain their telomerase levels: switching from regular to nonfat dairy products, adding two or three servings of fruits and vegetables to their diet, or doing just a few minutes of daily meditation, for example. The same may be true for other longevity boosters such as calorie restriction, which is thought to extend life span by boosting SIRT1, a protein involved in protecting and repairing DNA (and thus protecting against potential killers like heart disease and cancer). Cutting calorie intake by a hunger-pang-producing one third might help people live about 20 percent longer, suggests David Sinclair, a professor of pathology at Harvard Medical School who conducted studies, similar to the monkey one, in mice. He says reducing calories by a smaller amount--say, 50 calories a day--could moderately boost SIR

Ways to Avoid Aging & Calorie-Restricted Diets

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