Meta-analysis associates higher blood antioxidant levels with lower cataract risk Tuesday, July 16, 2013. The results of a meta-analysis published online on July 10, 2013 in the American Journal of Clinical Nutrition provides more evidence for a protective role for antioxidants against age-related cataract. Researchers at Guangzhou Medical University and Jinan University in Guangzhou, China selected 13 studies that included a total of 18,999 participants for their analysis. The included studies evaluated the risk of cataract in association with blood levels of vitamin A, vitamin C, vitamin E, alpha-carotene, beta-carotene, lutein, zeaxanthin, lycopene and beta-cryptoxanthin. When comparing lowest to highest blood antioxidant levels, having a high intake of vitamin E was associated with a 25% lower risk, alpha-carotene with a 28% lower risk, lutein with a 25% reduction and zeaxanthin with a 30% decrease in the risk of cataract. Among Asian populations, having a high vitamin A and vitamin C level were associated with a 31% and 33% risk reduction, however, the protective effect associated with these two vitamins was not observed among Westerners. In their discussion, authors Yu-Hong Cui and associates remark that the results of studies evaluating the association between cataract and antioxidant intake have been inconsistent, possibly due to the imprecise nature of self-reporting, and they note that blood levels of antioxidants may be a better marker of antioxidant status than dietary intake. Interventional studies involving the administration of various antioxidants may also provide inconsistent results due to an influence of lifestyle, environmental factors and individual variances in absorption on blood levels; the likeliness of long periods of time for protective effects to manifest, and other factors. "Our results provide additional evidence in support of a significant inverse association between blood levels of certain antioxidants and risk of age-related cataract, suggesting the elevation of blood levels of related antioxidants by appropriate methods might bring a benefit in age-related cataract prevention, especially for people with low basic levels of blood antioxidants," the authors conclude. "Large-scale, long-term randomized controlled trials should be carried out in different populations to investigate the efficacy of antioxidant intakes on cataract prevention."
Posted on: Wed, 17 Jul 2013 22:30:53 +0000
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