Glaucoma and Vitamins A, C, and E Supplement Intake and Serum Levels in a Population-Based Sample of the United States
Wang SY, Singh K, Lin SC
For this study, Wang, Singh, and Lin took advantage of publicly available data from the 2005-2006 National Health and Nutrition Examination Survey, an annual cross-sectional series of interviews and examinations of the civilian, noninstitutionalized population of the United States. Data on health conditions, participants' use of dietary supplements, and measurement of serum levels of these supplements were used to assess the relationship between self-reported glaucoma and the intake of vitamin A, C, and E in 2912 participants aged 40 years and older.
The intake of vitamins A, C, and E from dietary supplements and antacids were the primary predictor variables. Vitamins consumed during a 30-day period before the interview were averaged to determine daily intake. The population was divided into quartiles of intake for each of the vitamins, along with a "no intake" group. Serum levels of each vitamin (A, C, and E as alpha-tocopherol and gamma-tocopherol) were divided into quintiles, including undetectable or "zero serum" vitamin levels. Blood samples were collected in the morning and afternoon, and participants were not required to be in a fasting state.
The primary outcome variable was the presence or absence of self-reported glaucoma. Potential confounders before data analysis included age, sex, race, annual income, education, smoking (current and past), alcohol use, body mass index, and self-reported comorbid conditions (kidney disease, cancer, congestive heart failure, myocardial infarction, anemia, ocular conditions, and spherical equivalent on refraction).
The Rao-Scott Pearson-type chi squared and Wald tests were used to compare possible confounding variables (as listed above) between participants with and without self-reported glaucoma. Several multivariate logistic regression models were created and used to examine possible independent associations between supplemental vitamin intake or vitamin serum levels and self-reported glaucoma. Most confounding variables were excluded so that in the final adjusted model, no coexistent systemic medical condition was included, and only 1 visual comorbid conditions (self-reported diabetic retinopathy) was retained.
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Cite this: Shivani S. Kamat, Shuchi B. Patel. The Value of Vitamins in Glaucoma - Medscape - Jun 06, 2013.