Researchers Say Low-Cal Diet Cuts Aging
By LINDSEY TANNER, AP Medical Writer
1 hour agoUPDATED 1 HOUR 14 MINUTES AGO
CHICAGO - Longevity researchers say they've 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 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.
The non-liquid diets used in the study were high in fruits and vegetables
with less than 30 percent fat.
Average weight loss was about 18 pounds, slightly more in the liquid-diet
group.
Blood tests showed substantial decreases in the amount of age-related DNA
damage in each of the three dieting groups, compared with their initial
levels. That kind of microscopic damage is linked to cancer and other
age-related ailments, but it's unknown whether the small changes seen in the
study would affect the study volunteers' disease risks.
No changes were seen in the control group.
Insulin levels also decreased after six months in all three reduced calorie
groups. Core body temperature also dipped slightly in two low-calorie groups
but not in the liquid-diet or control group.
The results show that the diets are safe, and not impossible to follow,
Hadley said.
Kacy Collins, 34, a once sedentary Baton Rouge law clerk, said she joined
the study to lose weight and hoped that would reduce her risks for
age-related ailments that run in her family, including diabetes and heart
disease.
Assigned to the exercise group, Collins said the hardest part was
eliminating most sweets and exercising daily. But she said eating up to
seven servings of fruits and vegetables daily kept her feeling full. She has
stuck with the new habits and kept off most of the nearly 30 pounds she lost
since the study ended almost two years ago.
Collins said it will be a big bonus if the changes help her live longer,
too.
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On the Net:
JAMA: http://jama.ama-assn.org
Pennington research: http://calerie.pbrc.edu/pressrelease.html
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