The mean life span has plateaued in the developed countries at around 70 years. Future substantial increases in the mean life span are apt to be due to inhibition of the process(es) involved in aging. One potentially practical means of inhibiting the rate of human aging is based on the hypothesis that free radical reactions play a significant role in the degradation of biological systems. Experiments based on this hypothesis have been encouraging. For example, several inhibitors of free radical reactions have been found to increase the mean life span of mice when added to the daily diet; 2-mercaptoethylamine and butylated hydroxytoluene were the most effective. Likewise, decreasing the amount and degree of unsaturation of the dietary fat of female C3H mice resulted in a decrease in the mortality rate. The probable role of free radical reactions in the pathogenesis of four age-associated diseases - cancer, atherosclerosis, hypertension and amyloidosis - is discussed. It is suggested that the addition of one or more inhibitors of free radical reactions to nutritionally adequate and acceptable natural diets selected to minimize the intake of substances that might participate in random endogenous free radical reactions, may increase the average life span of man by five or more years, with accompanying increases in the years of useful, healthy life. © 1969 The American Geriatrics Society.
