Longevity researchers say they have shown for the first time that following a strict low-calorie diet can decrease DNA damage linked with aging.
Some people who took part in the six-month diet study ate as little as 890 calories a day. Their insulin levels fell and metabolisms slowed changes that are thought to increase longevity.
The findings are provocative, but preliminary. Longer-term research will try to sort out whether such changes can meaningfully extend people's lives, said senior author Eric Ravussin of the Pennington Biomedical Research Center at Louisiana State University.
"They are the first proof that what has been observed in rodents seems to be also working in humans," Ravussin said.
The results are from the first phase of research at the Baton Rouge center sponsored by a $12.4 million (Ђ10 million) National Institute on Aging grant. They follow unrelated research reported in January which suggested a very restrictive diet seemed to help the heart age more slowly.
The latest study appears in Wednesday's Journal of the American Medical Association.
"It's very exciting," said Dr. Evan Hadley, director of the NIA's geriatrics and clinical gerontology program.
"It's a step forward but not the whole journey," said Hadley, whose agency is part of the NIH.
The 48 participants, all slightly overweight, were randomly assigned to one of four groups: calorie restriction, which cut usual daily calories by 25 percent; calorie restriction plus exercise, which cut daily calories by 12.5 percent and increased physical activity by 12.5 percent five days a week; very low calories, with an 890-calorie liquid diet for up to about three months followed by a weight-maintenance diet; and a control group that aimed to keep weight steady.
Government dietary guidelines for weight maintenance recommend about 2,000 to 3,000 calories a day, depending on age, gender and activity level, with the higher amount generally for very active men, reports AP.
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