K. Kitani, T. Yokozawa, T. Osawa

The "Free Radical Theory of Aging" (FRTA) initially proposed by Harman [1]) half a century ago has been increasingly supported in recent years. However, while there have been a number of studies demonstrating a significant effect of antioxidant treatment in preventing experimentally induced pathologies that are believed to be at least partially caused by oxygen induced tissue damage, so-called antioxidant strategies have not been shown convincingly to be effective in increasing life spans of animals [2]). Accordingly, the general consensus of experimental gerontology in the last century was "The only reproducible means of prolonging survivals of animals is the calorie restriction paradigm."

As a challenge against this dogma, we attempted to examine the effect of two potent antioxidants, one tetrahydrocurcumin (TC), a biotransformed metabolite of curcumin contained in turmeric of Indian curry, and the other green tea polyphenols (PPs). Male C57L/6JNia (Harlan-Sprague Dawley, Ind.) began to receive treatments at the age of 13 months. In the TC experiment, animals received TC containing pellets (0.2%) or standard pellets (MF, Oriental Ltd., protein 24%). In the PPs experiment, animals received normal diets (MF) and normal drinking water or water containing green tea water extract product (Sunphenon 100S, Taiyokagaku, Yokkaichi, Japan) containing various PPs ( ลั70%) at a concentration of 80 mg/l both pasteurized by g ray irradiation. Survivals of animals were examined until deaths of these animals.

Average life span (days) in TC fed mice was 11.7% longer (882.2 ฑ154.6, mean ฑ S.D.) than in control mice (797.6 ฑ 151.2, both n=50) (P

Most of past attempts including that by Lipman and coworkers [2]) by nutritional means have failed in achieving a statistically significant prolongation of life spans of animals. However, as shown in the present study, some nutriceuticals appear to have potential of significantly increasing life spans of animals. Both nutriceuticals have been shown to be effective in preventing a number of experimentally induced age associated disorders including cancer, atherosclerosis and others. Furthermore, the advantage of these agents is the least toxic nature to humans which has been confirmed in human experimentation of thousands of years.

Since these agents are known to be effective in preventing atherosclerosis which does not involve wild type rodents but is the number one killer of elderly humans, it is expected that supplementation of these agents may be effective for prolonging the life span (at least health span) of humans possibly more effectively than observed in rodents.

In conclusion, nutritional approaches in prolonging the health span (if not life span) of humans may be more promising than believed before and deserves further extensive study using nutriceuticals possessing antioxidant properties.

1) Harman D. J. Gerontol. 12:257-263, 1956
2) Lipman RD et al. Mech Ageing Dev 103:269-284, 1998

Keywords (Optional): 
life span
green tea polyphenol