Journal Article

Relations of Serum Ascorbic Acid and α-Tocopherol to Diabetic Retinopathy in the Third National Health and Nutrition Examination Survey

Amy E. Millen, Michael Gruber, Ron Klein, Barbara E. K. Klein, Mari Palta and Julie A. Mares

in American Journal of Epidemiology

Published on behalf of Johns Hopkins Bloomberg School of Public Health

Volume 158, issue 3, pages 225-233
Published in print August 2003 | ISSN: 0002-9262
Published online August 2003 | e-ISSN: 1476-6256 | DOI: http://dx.doi.org/10.1093/aje/kwg116
Relations of Serum Ascorbic Acid and α-Tocopherol to Diabetic Retinopathy in the Third National Health and Nutrition Examination Survey

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The protective relation of ascorbic acid and α-tocopherol to the development of diabetic retinopathy has not been thoroughly evaluated in epidemiologic studies. The association of prevalent diabetic retinopathy with serum ascorbic acid and α-tocopherol was studied among participants with type 2 diabetes (≥40 years) (n = 998) in the Third National Health and Nutrition Examination Survey (1988–1994); 20% of the sample (n = 199) had prevalent retinopathy. The overall odds ratio for retinopathy among participants in quartile 4 compared with quartile 1 for serum ascorbic acid was 1.3 (95% confidence interval: 0.8, 2.3), with a p for trend = 0.60 after adjustment for the confounders of smoking, race, waist/hip ratio, hypertension, and duration of diabetes. The overall odds ratio for retinopathy among participants in quartile 4 compared with quartile 1 for serum α-tocopherol was 2.7 (95% confidence interval: 1.6, 4.6), with a p for trend = 0.14 after adjustment for confounders. After removal of supplement users of vitamin C (n = 307) or vitamin E (n = 298), the odds ratio changed direction or was attenuated: adjusted odds ratios for retinopathy among participants in quartile 4 compared with quartile 1 for serum ascorbic acid and α-tocopherol = 0.7 (95% confidence interval: 0.3, 1.4) and 1.6 (95% confidence interval: 0.9, 2.9), respectively. In summary, no significant associations were observed between serum levels of major dietary antioxidants and retinopathy. Recent use of supplements for treatment of complications of diabetes may explain the direct associations.

Keywords: ascorbic acid; diabetic retinopathy; nutrition surveys; vitamin E; Abbreviation: NHANES III, Third National Health and Nutrition Examination Survey.

Journal Article.  6030 words. 

Subjects: Public Health and Epidemiology

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