AGE
, Volume 17, Issue 4, pp 119-146

Aging: Prospects for further increases in the functional life span

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Abstract

Life spans in the developing countries now range from 76–79 years, 6–9 years less than the limit of 85 years imposed by aging. Aging is the accumulation of changes that increase the risk of death. Aging changes can be attributed to development, genetic defects, the environment, disease, and the major contributor, the inborn aging process. In 1954 the free radical theory of aging proposed that aging was caused by free radical reactions. Support for this theory is now extensive. There is a growing consensus that the theory is correct and that in mammals, aging is the accumulation of deleterious changes produced by free radical reactions, most initiated by the mitochondria (at an increasing rate with age), while the life span is determined by the rate of such damage to the mitochondria. This consensus bodes well for future efforts to increase the functional life span, i.e., the period of healthy, productive life. Some of the data which resulted in this consensus are presented.

Studies based on the free radical theory of aging suggest that the average life expectancy at birth (ALE-B), a rough measure of the functional lifespan, can be increased in the developed countries (in addition to the 3–5 years that may optimistically still be achieved by conventional measures), so as to more closely approach the potential “natural” maximum value of 85 years—and to exceed it if the aging process is slowed. This can be accomplished by: 1) keeping body weight down, at a level compatible with a sense of well-being, 2) ingesting diets adequate in essential nutrients and designed to minimize random damaging free radical reactions in the body, 3) supplementing the diet with one or more antioxidants, e.g., β-carotene, and vitamins C and E, and 4) employing measures to minimize accumulation of metals in the body capable of initiating adverse free radical reaction and of those than can impair the activity of some enzymes.