July 14th, 2009

By Barbara Kessler
Green Right Now

Eating leaner could help prolong life as we know it on the planet, by reducing the resources devoted to energy-intensive foods, like industrially produced meat.

Now a study of calorie-restriction involving monkeys suggests that eating less overall could extend our own lives, and help us age more healthfully.

The University of Wisconsin study, published in the journal Science this month, compared rhesus monkeys raised for most of their lives on diets that were substantially the same but differed in total calories. The colony of 76 monkeys was divided into two groups. One group was allowed to eat as much as they wanted during the day, while the other half was restricted to about 30 percent fewer calories. The restricted monkeys were given vitamin supplements to assure that they did not become malnourished.

Researchers watched the monkeys over 20 years, and released their findings now because many of the monkeys, whose average lifespan is 27 years (though they can live to age 40), are hitting their golden years. (See photo above of Canto, 27, on the left, who has been on the calorie-restricted diet, and Owen, 29, who ate freely.)

The 20-year study found that:

• 63 percent of the calorie restricted group is alive compared with 45 percent of those allowed to eat freely

• Five of the calorie-restricted monkeys were lost to age-related cancer and cardiovascular disease compared with 14 monkeys lost to those old-age diseases among the heavier eaters

• None of the restricted monkeys have developed diabetes

• Scans of their brains showed less deterioration in areas controlling memory, motor and executive functions.

“We have been able to show that caloric restriction can slow the aging process in a primate species,” says lead researcher Richard Weindruch, a professor of medicine in the UW-Madison School of Medicine and Public Health, in a statement. “We observed that caloric restriction reduced the risk of developing an age-related disease by a factor of three and increased survival.”

Some scientists have criticized the results as being statistically insignificant or pre-mature, but others consider the differences in the two groups to be notable, according to news articles.

The concept that calorie restriction could lead to a healthier life is rooted in mice studies from the 1930s which discovered that the shortage of food led to metabolic reaction that primed the body for survival.

Because eating less by ignoring appetite signals is extremely difficult, researchers are looking at ways to help tap into this response by using supplements or drugs.

Releases by Science and the University of Wisconsin did not address whether the confined monkeys exercised.

(Photo credit: Canto and Owen by Jeff Miller)

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