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How Much You Eat May Affect How Long You Live

15-year study results show similar results in chimpanzees and humans

THURSDAY, Aug. 1, 2002 (HealthDayNews) -- Government scientists say they've completed the beginning steps toward establishing a relationship between your food consumption and your longevity.

The next step could be far more dramatic: a "pill" that would let you eat all you want, yet stay trim and healthy and live longer. But such a miracle compound is way off in the future.

Here's what scientists have found, as reported in the tomorrow's issue of the journal Science:

The hunt for a molecule that would fill the bill comes out of research on diet and aging that started 15 years ago and is just edging into human work, says George S. Roth, a senior guest scientist at the National Institute on Aging.

"We've known for 70 years that if you feed rats and mice less, they live longer and are healthier," says Roth. "But until 1987, that had no been tested in an animal living more than 15 years. So, we started the first monkey trial."

He adds: "That trial is now in its 15th year, and it is showing what a lot of people predicted. Monkeys that eat 30 percent less food than normal are healthier and seem to be aging slower, with half the expected death rate."

To monitor the monkeys' health, Roth and his colleagues look at three biomarkers -- body temperature, blood insulin levels and blood levels of DHEAS, an adrenal gland hormone that appears to be important in health maintenance and whose production declines with age. They have reported that the longer-living monkeys have lower body temperature, lower insulin levels and higher DHEAS levels.

Now they are reporting what seems to be the same effect in humans, specifically, 700 men participating in the Baltimore Longitudinal Study of Aging. The Science report did not measure calorie intake directly, but instead looked at the relationship between the three biomarkers used in the monkey study and longevity.

"We wanted to see how the results that show up clearly in the animal model translate to humans," says Dr. E. Jeffrey Mettler, a medical officer in the NIA clinical research branch who leads the Baltimore study. "This is our first go at taking that step."

What they found in the humans was what has been found in the monkeys: lower levels of insulin, lower body temperature and higher DHEAS levels are associated with longer lives.

But the results are so tentative and the link with calorie intake so indirect that the most Mettler will say is that "there is some evidence that the idea might not be totally wrong."

What's clear, he adds, is that the results support the well-accepted view that "being overweight is not healthy" -- a critical fact because studies show that 60 percent of Americans are overweight.

And Roth says that while "monkeys and probably people too, benefit from calorie restriction," he acknowledges that "most people would be unwilling or unable" to reduce their calorie intake by 30 percent. (The average American man consumes between 2,100 and 3,000 calories a day; because women weigh less, their intake is 25 percent lower.)

Which brings up the diet pill, something that "mimics the effects of caloric restriction without having to diet," Roth says. "It is a compound like glucose that works by inhibiting the enzyme that metabolizes glucose, so not as much is metabolized into fat."

Animal work with the compound, 2-deoxyglucose, shows that it is effective in rodents, Roth says.

"But we would not recommend that people take it," he adds. "There is a very narrow window between the effective dose and a toxic dose."

So the hunt is on for a molecule that would have the same effect without being dangerous.

"We think we will be able to find other natural compounds that do the same thing," Roth says. "There are many compounds that can be screened."

What To Do

Until the perfect diet pill comes along, you might get help in curbing that impulse to wolf down food by reading about the National Heart, Lung and Blood Institute's Obesity Education Initiative. And here are a few tips for making healthier meals.

SOURCES: George S. Roth, Ph.D, senior guest scientist, and E. Jeffrey Mettler, M.D., medical officer, clinical research branch, National Institute on Aging, Baltimore; Aug. 2, 2002, Science
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