09 July 2008

Once again about the old recipe for prolonging life

It has long been known that calorie restriction slows down aging in mice and rats. According to one of the most popular hypotheses, this effect is due to a decrease in the synthesis of the thyroid hormone triiodothyronine (T3), which leads to a slowdown in metabolism and, accordingly, tissue aging.

According to the results of a study conducted by scientists at St. Louis University, working under the guidance of Dr. Edward Weiss, reducing the calorie content of the diet by 300-500 kilocalories per day leads to a similar biological effect in the human body and can slow down aging.

As part of their work, the researchers wanted to find out whether limiting the calorie content of the diet causes a decrease in the level of triiodothyronine in the human body. In order to make sure that the decrease in triiodothyronine levels is the result of caloric restriction of the diet, and not weight loss, they recruited volunteers who had to lose weight through physical training.

The study participants were sedentary, non-smokers, 50-60-year-old men and postmenopausal women with normal or slightly elevated body mass index. All of them were in good health and had no cardiovascular diseases, diabetes, lung diseases, uncontrolled hypertension and signs of malignant diseases.

The volunteers were randomly divided into 3 groups: a group with a calorie restriction, a training group and a control group. The members of the first group daily cut their diet by 300-500 calories, and the second – adhered to their usual diet and regularly trained.

The members of both experimental groups experienced approximately the same decrease in body weight, while the members of the group with a calorie restriction diet simultaneously experienced a decrease in the level of thyroid hormone.

Despite the need for a thorough long–term study, Wise believes that limiting the calorie content of the diet by 300-500 calories per day is far from a bad idea. However, it is necessary to remember the basic principle: replacing high-calorie food with low-calorie dishes, but rich in various nutrients.

He also notes that a reasonable reduction in the calorie content of the diet should not lead to anorexia nervosa – a mental illness that can eventually lead to various somatic diseases and even death.

It should also be borne in mind that the body is able to adapt to calorie restriction of the diet, and slowing down the metabolism over time can increase the predisposition of people to accumulate excess weight even on a moderately high-calorie diet. Therefore, according to the authors, the key to maintaining a normal body weight is a combination of following an adequate diet and regular physical activity.

The next stage of the work is to obtain evidence that a decrease in the level of triiodothyronine is indeed at least one of the mechanisms for slowing down the aging processes associated with age of human tissues as a result of a full-fledged low-calorie diet and moderate physical exertion. However, the authors acknowledge that the only way to obtain convincing evidence is to conduct a long-term study.

Portal "Eternal youth" www.vechnayamolodost.ru based on the materials of ScienceDaily


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