Can cutting way back on calories for the rest of your life help make that life longer and healthier? Researchers have suspected so since the 1930; studies in animals, fungi and humans have shown promising results; and books like The Longevity Diet: Discover Calorie Restriction have become bestsellers. Now, a team of Swedish researchers has discovered a new reason why this diet might work to slow the aging process: Calorie restriction helps stop the deterioration of peroxiredoxin, an enzyme in our bodies that’s essential for preventing age-related health decline.
Peroxiredoxin, or Prx1, counteracts damage to our genetic material, explained study leader Mikael Molin, a professor of cell and molecular biology at the University of Gothenburg. Prx1 generally becomes less active as we age, but calorie restriction can prevent this by increasing production of another enzyme, Srx1, which repairs Prx1.
Calorie restriction, or ‘CR,’ has been shown in animals like monkeys and mice to slow the aging process and lead to less age-related health problems. In humans, small scale studies have shown those practicing calorie restrictive diets have less risk factors for bad health (though CR’s long-term effects on human health are still unknown).
Practitioners of calorie restriction consume about 30% less calories than the daily recommended caloric intake (for someone on a 2,000-calorie-per day diet, then, that would mean cutting to about 1,400 daily calories). But they don’t just load up on sugar-free jello, diet coke and broccoli like some sort of science-sanctioned anorexics—part of calorie restriction for longevity means eating a nutritionally sound diet, too.
A clinical trial of calorie restriction in humans, financed by the National Institutes of Health, is currently underway. The New York Times Magazine ran a story on it last month, which nicely explains the impetus behind CR:
The aging process, which researchers sometimes call “primary” or “intrinsic” aging, refers to the damage that ordinarily accumulates in our cells as we grow older, a natural condition that seems to have limited the maximal lifespan of humans to 120 years. Diseases that accompany the aging process — often called “secondary aging” — are those afflictions increasingly prevalent in the elderly, like cancer, diabetes and cardiovascular disease.
There seems little doubt that calorie restriction can have significant effects on secondary aging. [...] Meanwhile, the experiment aims to shed some light on the more complex and still-unsettled question of whether calorie restriction affects primary aging, and thus longevity, in humans.
There are a lot of theories as to why CR can slow age-related decline or boost longevity, but nothing has been conclusive; this Swedish study is just the latest in a series of clues to how and why the process of calorie restriction works. Interestingly, though, the study could show a way to mimic CR without any restricting involved. If CR’s benefits stem from increasing Srx1 in cells, then perhaps aging could be delayed by boosting Srx1 in cells alone.