Food: Eat less, die less

July 10, 6:54 PMSF Health News ExaminerJefferson Adams

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This May 28, 2009, photo provided by the University of Wisconsin at Madison
via the journal Science shows Rhesus monkeys Canto, 27, left, who eats a
restricted diet, and Owen, 29, who eats an unrestricted diet, at the Wisconsin
National Primate Research Center at the University of Wisconsin-Madison.
The two are among the oldest surviving subjects in a pioneering study of the
links between diet and aging in Rhesus macaque monkeys. The 20-year study
found cutting calories by almost a third slowed the aging of monkeys, and
fended off death, and shows the first evidence that it delays the diseases of
aging in primates too, researchers from the University of Wisconsin report
in the Friday, July 10, 2009, issue of the journal Science.
(AP Photo/UW-Madison University, Jeff Miller)

Can you fend off death, and live a healthier, longer life just by reducing the amount of food you eat every day? Science increasingly says: 'yes.'

Over the last 70 years, numerous studies have shown the beneficial effects reduced-calorie diets on the life spans of organisms as widely varied as yeast and dogs. Now, for the first time, a long term study on monkeys has shown that cutting calories slows the aging process and reduces the risk of disease.

Scientists compared monkeys on restricted diets to those on unrestricted diets over a twenty year period beginning in 1989. The monkeys whose diets were not restricted died at rates three times higher than those whose calories were controlled. Writing in Science, the US research team praised what they called the "major effect" of the diet.

The results came by cutting calorie intake by 30% while maintaining nutrition, and seem to benefit numerous age-related diseases common in monkeys, including cancer, diabetes, cardiovascular disease and brain atrophy.

Whether human can enjoy the same effects remains unclear, although anecdotal evidence does suggest that people on a long-term calorie-restricted diet enjoy better cardiovascular health.

Scientists don't understand exactly how the process works. Theories currently focus on metabolic triggers, or reduced production of "free radical" which can damage cells.

For the trial, scientists monitored seventy-six rhesus monkeys. Half had their daily food intake cut by 30%, half were allowed to eat freely at feeding time. Animals on the restricted diet had rates of cancers and cardiovascular disease that were half of those permitted to eat freely.

Healthier brains
Interestingly, the monkeys on restricted diets seemed to enjoy healthier brains over time. While nearly all brains shrink with age, those exposed to the restricted diet appeared better preserved and larger in volume, at least in certain regions, especially those areas associated with movement and memory.

"Both motor speed and mental speed slow down with ageing," said Sterling Johnson, a neuroscientist at the University of Wisconsin-Madison School of Medicine. "Those are the areas which we found to be better preserved. We can't yet make the claim that a difference in diet is associated with functional change because those studies are still ongoing."

"What we know so far is that there are regional differences in brain mass that appear to be related to diet." Earlier this year, German researchers published findings from their study of elderly people which suggested that calorie reduction appeared to improve memory over a period of just three months.

No diabetes
Monkeys who ate freely often had diabetes and problems with glucose regulation, while there were no cases of diabetes in the calorie controlled group.

The diet restriction results look promising. Ultimately, more study will need to be done to determine any benefits humans may enjoy on such a diet. Also, people will ultimately have to decide for themselves if they are prepared to eat less food for the promise of a longer life.