Lifespan and reproduction in <i>Drosophila</i> : New insights from nutritional geometry

TLDR

Modest dietary restriction (DR) prolongs life across a wide range of organisms, from yeast to mammals. The study uses recent nutritional techniques to quantify how diet, nutrient intake, lifespan, and reproduction relate in *Drosophila melanogaster*. Flies were offered complementary foods and regulated their intake to maximize lifetime egg production. Caloric restriction did not extend lifespan, while lifespan and fecundity were maximized at distinct protein‑to‑carbohydrate ratios—1:16 for longevity, 1:2 for egg‑laying rate, and 1:4 for lifetime egg production—highlighting direct reproductive costs and adverse effects of high protein intake and unifying previously conflicting work into a common aging framework.

Abstract

Modest dietary restriction (DR) prolongs life in a wide range of organisms, spanning single-celled yeast to mammals. Here, we report the use of recent techniques in nutrition research to quantify the detailed relationship between diet, nutrient intake, lifespan, and reproduction in Drosophila melanogaster. Caloric restriction (CR) was not responsible for extending lifespan in our experimental flies. Response surfaces for lifespan and fecundity were maximized at different protein-carbohydrate intakes, with longevity highest at a protein-to-carbohydrate ratio of 1:16 and egg-laying rate maximized at 1:2. Lifetime egg production, the measure closest to fitness, was maximized at an intermediate P:C ratio of 1:4. Flies offered a choice of complementary foods regulated intake to maximize lifetime egg production. The results indicate a role for both direct costs of reproduction and other deleterious consequences of ingesting high levels of protein. We unite a body of apparently conflicting work within a common framework and provide a platform for studying aging in all organisms.