The effect of feeding of two different antioxidants, tetrahydrocurcumin (TC) and green tea polyphenols (PPs) on the survival of male C57BL/6 mice was examined. Mice that started to receive diets containing TC (0.2%) at the age of 13 months had significantly longer average life spans (days, mean +/- SD) than control mice (797.6 +/- 151.2 vs.882 +/- 154.6, both n = 50, controls vs. TC treated, plus 11.7%, P < 0.01). The 10% longest survival was also significantly greater in TC-treated mice (plus 6.5%, P < 0.01). In contrast, in mice that started to receive TC in their 19th month of life, no significant difference from the control mice was found for either the average life span or the 10% longest survival. In mice that received water containing PPs (80 mg/l), the average life span was also significantly longer than in the control mice (801 +/- 121.5 vs. 852.7 +/- 88.2, plus 6.4%, P < 0.05), although the 10% longest survival was not significantly different from that in the control mice (P > 0.05). The body weights of the TC (but not PP) fed mice, were slightly (2-4%) but significantly (P < 0.05) lower than the values for the corresponding ages in the control mice in the first six months of treatment. Thereafter, the difference in average body weight between the control and the TC-fed animals was totally lost. Although an additional contribution of an unintended slight decrease in food intake due to TC feeding (suspected due to the difference in body weight) is not excluded, we suggest that the feeding of nutritional antioxidants such as TC and PPs may have the potential to beneficially modify the life spans of animals.