Mice Get Benefits of Dieting Without the Diet

Female mice lacking S6K1 lived an average of 950 days, over 160 days (or 20 percent) longer than the control group. For humans, that would be like adding 16 additional years of life.

Male mice, however, received little benefit from the single gene removal.

Female mice not only lived longer, but also were healthier and leaner. They had stronger bones, were more curious in their environment, had better regulated immune systems, were protected from Type II diabetes, and even saw improvements with other age-related ailments.

"We added years of life, but also life to those years," said Withers.

Other scientists, including Matt Kaeberlein, a scientist at the University of Washington who wrote an accompanying perspective for Science, are excited about the new study.

"I think there are lots of reasons to be optimistic that targeting this pathway could have therapeutic uses for age-related diseases," said Kaeberlein, adding that targeting the specific S6K1 pathway might be a better option than using rapamycin.

Cynthia Kenyon at the University of California, San Francisco, who studies longevity in worms, says the research could eventually be used to extend the lives of humans.

"This absolutely could have clinical uses," for human patients, said Kenyon. "This is a great result but not really surprising because knocking this gene out in worms and yeast extended their life spans."

However, the study doesn't imply that healthy folks should start taking metformin.

"I don't think (taking metformin) is a substitute for a healthy lifestyle," said Withers, adding that more studies are necessary before he would feel comfortable prescribing metformin for healthy, non-diabetics.

If millions of people have been taking metformin and rapamycin for decades, why hasn't anyone noticed, especially long-lived and healthy diabetics and organ transplant patients?

The simple answer, according to scientists, is that no one was looking.

Diabetes and organ transplants are serious enough that scientists didn't expect these patients would be able to live measurably longer than non-diabetic or organ transplant patients. As far at Kaeberlein and Withers know, no scientist has published a study looking at the life span of diabetic or organ transplant patients.

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