GAINESVILLE, Fla., - A lifelong habit of trimming just a few calories from the daily diet can do more than slim the waistline - a new study shows it may help lessen the effects of aging.
Scientists from the University of Florida's Institute on Aging have found that eating a little less food and exercising a little more over a lifespan can reduce or even reverse aging-related cell and organ damage in rats.
The discovery, described this month in the journal Antioxidants and Redox Signaling, builds on recent research in animals and humans that has shown a more drastic 20 percent to 40 percent cut in calories slows aging damage. The UF findings indicate even small reductions in calories could have big effects on health and shed light on the molecular process responsible for the phenomenon, which until now has been poorly understood.
"This finding suggests that even slight moderation in intake of calories and a moderate exercise program is beneficial to a key organ such as the liver, which shows significant signs of dysfunction in the aging process," said Christiaan Leeuwenburgh, Ph.D., an associate professor of aging and geriatric research at the UF College of Medicine and the paper's senior author.
UF scientists found that feeding rats just 8 percent fewer calories a day and moderately increasing the animals' activity extended their average lifespan and significantly overturned the negative effects of cellular aging on liver function and overall health.
An 8 percent reduction is the equivalent of a few hundred calories in an average human diet and moderate exercise is equivalent to taking a short walk.
But most people can't reduce their calorie consumption at all for a sustained length of time. So this is an interesting result and a reason to eat slightly less. But few will manage to pull that off.
The researchers also found that RNA is an earlier biomarker for aging than DNA.
To reveal the workings of the body's chemical climate when aging-related damage happens, UF researchers tracked levels of biomarkers - chemicals and molecules present in the liver - in groups of rats. The liver, a crucial organ for maintaining good health during aging, cleans the blood and helps regulate the body's immune system. The researchers also plan to assess the same biomarkers in a study of rats' hearts, muscle and brains.
The research team was surprised to find one of the biomarkers, RNA, which is important for coding DNA and for protein synthesis, is more quickly damaged by aging than the more frequently studied DNA. RNA damage, therefore, could be an excellent early signal to indicate the onset of aging, researchers say.
"Because it is more sensitive to oxidative stress, RNA can be useful as an early marker of oxidative damage and even aging," said Arnold Y. Seo, a doctoral student in UF's Institute on Aging.
Better aging biomarkers that detect changes at earlier stages allow more rapid testing of potential life extending therapies.
Another study on rats found important clues for how calorie restriction lengthens life expectancy. Mice lacking a growth hormone receptor and with lower resulting insulin live longer than normal mice.
"The implication ... for pharmaceutical development would be that the signaling pathways of growth hormone and insulin may be logical targets for development of anti-aging medicine," Dr. Andrezej Bartke from Southern Illinois University in Springfield told Reuters Health.
However, in sharp contrast to its effects in normal mice, calorie restriction failed to increase lifespan in mutant mice lacking growth hormone receptor. "The present findings show that growth hormone resistant mice fail to respond normally to calorie restriction, a very effective life-extending intervention," Bartke said.
I think the idea here is that the reduction in growth hormone receptor delivers the life extension benefit that calorie reduction would normally deliver. So when calories are reduced in these mice there is not an additional benefit from the calorie reduction.
Update: You can read the paper in the Proceedings of the National Academy Of Science by Bartke's group in abstract and the full paper in open access.
|Share |||Randall Parker, 2006 May 08 10:35 PM Aging Diet Studies|