Roundworms low on insulin tend to live longer, and a new study identifies a protein that helps explain the effect. Low insulin levels increase this protein's activity in the gut, where the protein can extend longevity by helping cells avoid damage.
Humans and other mammals have a similar group of proteins, suggesting that insulin probably affects the proteins' activity in people as well, the researchers say. The discovery could help explain why calorie-restricted diets extend life span in animals and why diabetes reduces life expectancy.
"The link with insulin is tantalizing," says study leader T. Keith Blackwell of the Joslin Diabetes Center at Harvard Medical School in Boston. However, "we'll need more research to show if this [link] has anything to do with dietary restriction or diabetes."
Scientists have known since the 1930s that yeast and many animal species live 30 to 50 percent longer when they are fed a spartan diet, containing about one-third fewer calor