In a laboratory at the Wisconsin National Primate Research Centre, Matthias is learning about time’s caprice the hard way. At 28, getting on for a rhesus monkey, Matthias is losing his hair, lugging a paunch and getting a face full of wrinkles.
In the cage next to his, gleefully hooting at strangers, one of Matthias’s lab mates, Rudy, is the picture of monkey vitality, although he is slightly older. Thin and feisty, Rudy stops grooming his smooth coat just long enough to pirouette toward a proffered piece of fruit.
Tempted with the same treat, Matthias rises wearily and extends a frail hand. “You can really see the difference,” said Dr Ricki Colman, an associate scientist at the centre who cares for the animals.
What a visitor cannot see may be even more interesting. As a result of a simple lifestyle intervention, Rudy and primates like him seem poised to live very long, very vital lives.
The approach, called calorie restriction involves eating about 30 per cent fewer calories than normal while still getting adequate amounts of vitamins, minerals and other nutrients. Aside from direct genetic manipulation, calorie restriction is the only strategy known to extend life consistently in a variety of animal species.
How this drastic diet affects the body has been the subject of intense research. Recently, the effort has begun to bear fruit, producing a steady stream of studies indicating that the rate of ageing is elastic, not fixed, and that it can be manipulated.
In the last year, calorierestricted diets have been shown in various animals to affect molecular pathways likely to be involved in the progression of Alzheimer’s disease, diabetes, heart disease, Parkinson’s disease and cancer. Earlier this year, researchers studying dietary effects on humans went so far as to claim that calorie restriction may be more effective than exercise at preventing age-related diseases.
“The effects are global, so calorie restriction has the potential to help us identify anti-ageing mechanisms throughout the body,” said Richard Weindruch, a gerontologist at the University of Wisconsin who directs research.
Ageing is a complicated phenomenon, the intersection of an array of biological processes set in motion by genetics, lifestyle, even evolution itself. Still, in laboratories around the world, scientists are becoming adept at breeding animal Methuselahs, extraordinarily long lived and healthy worms, fish, mice and flies.
“In mice, calorie restriction doesn’t just extend life span,” said Leonard P. Guarente, professor of biology at the Massachusetts Institute of Technology. “It mitigates many diseases of ageing: cancer, cardiovascular, neurodegenerative disease. The gain is just enormous.“ Researchers at Washington University in St. Louis have been tracking the health of small groups of calorie-restricted dieters. Earlier this year, they reported that the dieters had better-functioning hearts and fewer signs of inflammation, which is a precursor to clogged arteries, than similar subjects on regular diets.
In previous studies, people in calorie-restricted groups were shown to have lower levels of LDL, the so-called bad cholesterol, and triglycerides. They also showed higher levels of HDL, the socalled good cholesterol, virtually no arterial blockage and remarkably low blood pressure.
Researchers at Louisiana State University reported in April in The Journal of the American Medical Association that patients on an experimental lowcalorie diet had lower insulin levels and body temperatures, both possible markers of longevity, and fewer signs of chromosomal damage typically associated with ageing.
Despite the initially promising results, some scientists doubt that calorie restriction can work effectively in humans.
A mathematical model published last year at University of California, Los Angeles, and University of California, Irvine, predicted that the maximum life span gain for humans would be just 7 per cent. A more likely figure, the authors said, was 2 per cent.
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