Extensive research in animals suggests that strict diets that limit the intake of certain nutrients increase lifespan and reduce the incidence of age-related disease. It may even be possible to reproduce these effects using drugs. For now, however, there are no clinically proven anti-aging diets or drugs, and scientists have not yet established their safety.
Diets that purport to slow the aging process are becoming increasingly popular.
Their proponents cite evidence that nutrient-restricting diets can increase healthy lifespan — at least in laboratory organisms such as yeast, worms, flies, and rodents.
In 1917, the journal Science published the first study to show that restricting the calorie intake of rats can delay the animals’ development and dramatically increase their lifespan.
More than 100 years later, the same journal has published a roundup of the best research to date into the efficacy and safety of diets that claim to slow the aging process.
Scientists at the University of Washington in Seattle and Pennington Biomedical Research Center in Baton Rouge, CA, conducted the review of popular anti-aging diets.
These include not just caloric restriction but also diets that strictly limit a person’s intake of carbohydrates, proteins, or particular amino acids.
The scientists also reviewed the evidence for the efficacy of various fasting regimes.
Remarkably, most of these diets appear to exert favorable effects on health and aging through their influence on a single metabolic pathway that yeast, worms, rodents, and humans have in common.
In theory, existing drugs that target this pathway could reproduce the diets’ beneficial effects without the need to go hungry or give up particular types of food.
While the authors of the new review offer an optimistic forecast for the future of anti-aging diets, they caution that they may not work equally well for everyone.
For some people with a particular genetic makeup or under certain environmental conditions, the diets may actually be detrimental to health.
The reviewers emphasize that there are no clinically proven anti-aging diets and conclude that more research is needed before doctors can recommend such diets for otherwise healthy people.
When researchers restrict the calorie intake of mice and rats — while providing all the essential nutrients they need — the animals are healthier and their average lifespan increases compared with animals fed an ordinary lab diet.
In addition, these rodents have a reduced incidence of age-related diseases, including cancer, neurodegenerative disorders, cardiovascular disease, and type 2 diabetes.
There is a clear inverse relationship between calorie intake and lifespan in the animals, up to about 50% calorie restriction. Animals that begin these diets while still young appear to reap the most benefits.
Whereas the results of research into calorie restriction in lab animals are clearcut, say the authors of the review, whether they apply to humans is less obvious.
The authors point out that researchers typically house mice and rats in ideal, pathogen-free conditions and keep a close eye on their health.
By contrast, the enormous variations in human environments and lifestyles are likely to have a large impact on the health effects of potential life-extending diets. Genetic …….