Supplements in the News

Antioxidants Help Eyes, High-GI Foods Hurt
Published Thursday, June 1, 2006

ROCKVILLE, Md.--High intake of antioxidant vitamin and mineral supplements is inversely associated with age-related macular degeneration (AMD), and consumption of high-glycemic index (GI) foods may lead to cortical or nuclear opacities, according to a review of existing literature ( Cochrane Database Syst Rev, 2:CD000254, 2006) and a cross-sectional analysis of baseline data from Age-Related Eye Disease Study (AREDS) ( Am J Clin Nutr, 83, 5, 1177-84, 2006).

In the Cochrane review, researchers searched for randomized, controlled trials on the effects of antioxidant vitamin or mineral supplementation, or both, on the progression of AMD, in the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library (2005, Issue 4); MEDLINE (1966 to Jan. 2006); SIGLE (1980 to March 2005); EMBASE (1980 to Jan. 2005); NRR (2005, Issue 4); AMED (1985 to Jan. 2006); and PubMed reference lists of identified reports and Science Citation Index (Jan. 24, 2006; covering previous 60 days). They also contacted investigators and experts in the field for details of unpublished studies. Trial quality was assessed and data from the trials were extracted and, where appropriate, pooled using random-effects and fixed-effects models. In the end, eight trials were selected for inclusion in the review. Supplementation with antioxidant vitamins and minerals including beta-carotene, vitamin C, vitamin E and zinc was inversely related to progression to advanced AMD, and individuals supplementing with these compounds were less likely to lose 15 or more letters of visual acuity than people not supplementing. The authors of the review noted the selected trials were small and had inconsistent results and called for future large, well-conducted, randomized, controlled trials in other populations.

In the AREDS study, researchers from Tufts University looked for an association between dietary carbohydrates or GI and cataract in nondiabetic persons, in data obtained from 3,377 AREDS participants (aged 60 to 80 years; 56 percent female), using a modified Block food-frequency questionnaire. Lens status was evaluated with the AREDS System for Classifying Cataracts. For participants in the highest quartile of intake, dietary GI was associated with a higher prevalence of all pure nuclear opacities and moderate nuclear opacities. The odds ratio (OR) between the highest and the lowest quartiles of intake was 1.27 for cortical opacities of any severity, and 1.71 for moderate cortical opacities. The researchers concluded dietary glycemic quality and dietary carbohydrate quantity may be associated with prevalent nuclear and cortical opacities, respectively.

These abstracts provided courtesy of Natural Products Industry Insider, published by Virgo Publishing Inc.

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