Long life may stem from a proper imbalance of dietary nutrients. A new study in fruit flies suggests that the life-extending properties of caloric restriction may be due not only to fewer calories in the diet, but also to just the right mix of protein building blocks, called amino acids.
The study, published online December 2 in Nature, may help explain some of the health benefits of restricted-calorie diets. Coupled with other data, the new study should prompt researchers to reevaluate whether it is calorie count or the nutrient composition of a diet that is most important for regulating lifespan and health, comments Luigi Fontana of Washington University in St. Louis. Caloric restriction--a diet that contains a minimal amount of calories while maintaining healthy levels of nutrients--has been proven to extend lifespan in fruit flies, worms, mice, dogs, baboons and other organisms. Nutritious, low-cal diets also improve health in people, but scientists don't yet know whether such diets can extend maximal lifespan in humans.