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Last Updated: Nov 12th, 2006 - 20:38:00 |
April 4 (foodconsumer.org) - A low calorie diet may extend the human lifespan by lowering body temperature, insulin levels and reducing DNA damage, according to a new study published in the Journal of the American Medical Association.
Low calorie diets or diets restricted in calories are known to elongate the lifespan of rodents and many other small animals. The low calorie diet is believed by many to have the same effect on humans. The current study might be the first to have provided the evidence at the molecular level showing that a low calorie diet may add years to one¡¯s lifespan.
In the study, 48 overweight people in four groups were assigned to four diets with different amounts of calories. One diet contained the normal amount of calories and other three had reduced amounts of calories.
During the six-month study, researchers from the Pennington Biomedical Research Center at Louisiana State University in Baton Rouge measured a series of physical and chemical parameters including hormone levels, body temperature, fasting insulin levels, fat mass and weight loss. They also examined energy expenditure and DNA damage.
People who ate fewer calories had not only lowered their fat mass and body weight, but also decreased their insulin level at fasting, body temperature, energy expenditure and DNA damage, all potentially protecting against aging.
Lower insulin and lower body temperature are good biomarkers of increased longevity. A previous four-year study of c ynomolgus m onkeys by Cefalu W.T. et al. resulted in the same conclusion that a low calorie diet significantly improves insulin sensitivity. The study was reported in the Oct. 2004 issue of Journal of Gerontology: Biological Sciences.
The effect of low-calorie diets on oxidative DAN damages were also found by other researchers. Djuric Z and Kritschevsky D reviewed previous studies on the subject and concluded that a calorie restricted diet has a protective effect against oxidative DNA damage. They published their article in the issue in the December, 1993 issue of Mutat Res.
DNA damage can be elevated when a high calorie diet is used. In a study published in the August, 1992 issue of Toxicol Appl Pharmacol, Djuric Z et al. tested the DNA damage in r ats and found that those eating a normal diet had a significantly higher DNA damage than those eating a diet with calories reduced by 40 percent.
Critics say that the current study looked only at the effect of a low calorie diet on the markers of longevity, not the longevity per se, meaning the study does not seem significant. Some pointed out that the results of the study were derived from a small population of overweight people, suggesting that the findings may not be generalized to a general population.
However, the current study is not the only one suggesting that a low calorie diet may increase longevity in humans. Other studies have also provided evidence supporting the notion that low calorie diets may help people live longer. For instance, one small study found that eating a nutritionally balanced diet with the amount of calories reduced by 30 percent can significantly slow the aging process in the heart. The h earts of those whose caloric intake was restricted functioned like the h earts of much younger people. The study conducted by Dr. Luigi Fontana, of Washington University in St. Louis, and colleagues and published in the Jan. 17 issue of the American College of C ardiology.
Another study, conducted by Fontana and colleagues (reported in April 2004 in the Proceedings of the National Academy of Sciences) found that people on a low-calorie diet had low levels of b lood p ressure, c holesterol, and t riglycerides, which are similar to that of younger individuals. These people had a lower risk of developing d iabetes and reduced body fat.
Both studies suggest that low calorie diets are heart healthy, meaning use of low calories diets may reduce risk of premature death from h eart disease or s trokes. This is significant because h eart disease is the number one k iller in the US.
A low calorie diet has been known for nearly a century for its effect on aging. An imal studies constantly and consistently reveal that a nimals with intake of 30 percent less calories live 30 percent longer compared with those that were fed without calories restricted.
Many scientists agree that low calorie diets have an effect on aging. However, there is no consensus about how many extra years one can have by using a low calorie diet. According to John Phelan, an evolutionary biolog ist at UCLA and Dr. Michael Rose, a professor of ecology and evolutionary biology at the University of California, Irvine who published a study on aging in the Aug. 2005 issue of the journal Aging Research Reviews, low calorie diets will not work in humans the same way it does in some a nimals. Low calorie diets may only extend human life span by a few years.
© 2004-2005 by foodconsumer.org unless otherwise specified
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