Why Calorie Restriction Might Prolong Life

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"The discovery of pha-4 is the first gene required for dietary restriction, the first gene that's absolutely essentially and specific for the response of dietary restriction," added Dillin. "This lays down the cornerstone for defining the actual molecular pathways that respond to reduced food intake."

"The key new thing about this paper is identification of a particular pathway," said Rajesh Miranda, an associate professor of neuroscience and experimental therapeutics at the Texas A&M Health Science Center College of Medicine. "This points out how you could maintain longevity by affecting different pathways."

One other gene, sir-2, seems to be involved in caloric restriction and longevity, but it's unclear how it works.

Humans have three genes similar to the pha-4 gene in C. elegans. These genes belong to the Foxa family, and all are involved in regulating glucagon, a hormone produced by the pancreas that contributes to maintaining the body's energy balance, especially while fasting. This is different from the role of another pancreatic hormone, insulin.

"We think that the function of pha-4 will be highly conserved in mice and perhaps humans," Dillin said.

And, it's possible it will. "So far, everything that's known about longevity in worms has gone on to be true, at least as far as they can tell, in mice," Tissenbaum said. "We hope it will be true [in humans]."

If there is a similar gene in humans, the next question will be whether it can be modified so people can eat normal diets but still reap the benefits of eating less.

"We think we're on the right path," Dillin said. "Can we actually manipulate glucagon levels, and is that the sole target that's going to regulate dietary restriction?"

More information

The American Aging Association can tell you about growing older.