Can we slow down aging by eating less?

Like you saw here, excessive calorie consumption appears to accelerate the aging process in the brain, in addition to increasing the risk for several chronic diseases. Conversely there is evidence that restriction of calorie intake delays the effect of aging and even increases longevity substantially … at least in rodents.

Caloric restriction
Caloric restriction (CR) is a procedure that has received increasing attention by researchers in the field of aging, because of its beneficial effect on age-related diseases and longevity in some animal species. CR involves reducing the amount of calorie consumption considerably, without compromising the quality of nutritional intake necessary for the body to function well. Researchers usually either use specified minimal amount of calories necessary to maintain certain body weight or reduce former consumption by a certain percentage.

The effect of caloric restriction on the brain
Research has shown that CR can slow down age-related changes in rodents’ brains and increase longevity substantially. It has a protective influence on neurons in the hippocampus and cortex and delays oxidative damage to proteins and DNA, among other things. Animal research has also shown that CR seems to reduce amyloid-beta in the brain (protein fragments that accumulate between nerve cells and which are one of the hallmarks of Alzheimer’s disease).

We cannot determine for sure if CR has the same impact on longevity in humans and animals, because long-term, diet-controlled, survival research has not been conducted on humans. We have some clues though, as several studies have shown that temporary CR has positive effect on biomarkers of health and longevity, for example blood pressure, resting heart rate, lipid profile and levels of insulin. Some also claim the people of Okinawa as a testament to the positive impact of caloric restriction. The traditional Okinawa diet is 20-30% lower in calories than the Japanese average. The people of Okinawa have considerably lower rates of mortality from cardiovascular disease and certain types of cancer than the average Japanese. Their life expectancy is among the highest in the world and has been attributed, at least partly, to the traditional local diet.

A word of caution

Although the results of some studies indicate that CR has similar metabolic effect on humans and animals and has a positive impact on memory in humans, this line of research is relatively new. So a word of caution is in order. It is very possible that even moderate CR could have detrimental effect on certain groups of people, for example those with a minimal amount of body fat and the danger of malnutrition is always present. Unpleasant side effects have been reported, for example reduction in body temperature and libido. Excessive caloric restriction can of cause lead to harmful effects, for example anemia, muscle wasting, neurologic deficits and depression. Additional effects are those seen with anorexic patients, for example distorted body image, adverse changes in skin, hair, bones, bone marrow, cardiovascular system etc. A body max index of less than 18,5 is associated with increased mortality rate in adults of all ages.

Vegetarian dietIf people would generally find it easy to adhere to a low-calorie diet, obesity would not be as widespread as it is. Therefore it seems unlikely that many people would be willing to lower their intake of calories to the barest minimum to improve their lifespan and health. Fortunately the results of animal studies have already given scientists some ideas of how changes in the physiological state of animals on restricted diet contribute to health and longevity. Already there are research on CR mimetics, i.e. some intervention provoking similar benefits on aging and health to those seen in CR.

But … until we have the anti-aging pill that we can take with our breakfast, keep exercising and eating lots and lots of vegetable …. just in case!

Here is an ABC news video from YouTube on caloric restriction:

Fontana, L. og Klein, S. (2007). Aging, adiposity, and calorie restriction. JAMA: The Journal of the American Medical Association, 297(9), 986-994.

Ingram, D. K. og Roth, G. S. (2011). Glycolytic inhibition as a strategy for developing calorie restriction mimetics. Experimental Gerontology, 46(2-3), 148-154.

Wang, J., Ho, L., Qin, W., Rocher, A. B., Seror, I., Humala, N. o.fl. (2005). Caloric restriction attenuates beta-amyloid neuropathology in a mouse model of Alzheimer’s disease. The FASEB Journal.

Weiss E.P., Racette S.B., Villareal D.T., et al. (2006). Improvements in glucose tolerance and insulin action induced by increasing energy expenditure or decreasing energy intake: a randomized controlled trial. American Journal of Clinical Nutrition, 84:1033-1042.

Willcox, B. J., Willcox, D. C., Todoriki, H., Fujiyoshi, A., Yano, K., He, Q. o.fl. (2007). Caloric restriction, the traditional Okinawan diet, and healthy aging. Annals of the New York Academy of Sciences, 1114(1), 434-455.

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