The effect of aging on the antioxidative activity of astaxanthin in human aqueous humor

We previously evaluated the antioxidative effects of astaxanthin intake in the aqueous humor by measuring reactive oxygen species-related parameters, including O₂ ^•- scavenging activity, H₂O₂ level, and total hydroperoxides level. In this study, we analyzed the antioxidative effects of astaxanthin in relation to age in 16 males and 19 females (average age 71.3 and 70.6, respectively) who underwent bilateral cataract surgery on one side before and the other side after astaxanthin intake (6 mg/day for 2 weeks). None of the parameters correlated with age before astaxanthin intake, but only total hydroperoxides level was significantly correlated after the astaxanthin intake (r = 0.4, p<0.05). Total hydroperoxides levels were similar in younger and older patients (<70 vs ≥70 years) before astaxanthin, but decreased significantly more in younger patients (-0.21 ± 0.18 vs -0.05 ± 0.31, p<0.05) after the intake, resulting in significantly different levels (p<0.05). The previously observed decrease in mean total hydroperoxides levels following astaxanthin intake was therefore considered likely to be attributable to a greater response in younger subjects. Given that total hydroperoxides levels reflect general antioxidative status, astaxanthin intake may exert a greater antioxidative effect in younger patients. Further comparative studies involving younger subjects and different astaxanthin doses are needed.