Vitamin D Status and Early Age-Related Macular Degeneration in a Biracial Cohort

Abstract

Purpose: Vitamin D status has been hypothesized to protect against development of early age-related macular degeneration (AMD) via its anti-inflammatory properties and its possible beneficial influence on blood pressure control.<br />

Methods: We investigated the association between vitamin D status and prevalent early AMD (n=511 cases) among 9,734 participants (7,779 whites, 1,955 blacks) in the Atherosclerosis Risk in Communities Study, a community-based cohort. Vitamin D status was assessed with serum 25-hydroxyvitamin D (25(OH)D) concentrations from visit 2 (1990-92) and dietary intake assessed from a food frequency questionnaire at visits 1 (1987-89) and 3 (1993-95). Vitamin D and fish oil supplement (yes/no) use was assessed at visit 3. Early AMD was assessed at visit 3 with nonmydriatic retinal photographs of one randomly chosen eye. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for early AMD by clinically defined categories of 25(OH)D in nmol/L (deficient <30, inadequate 30-<50, and two categories of adequate status: 50-<75 and ≥75), by quintiles (Q) of vitamin D intake (IU/day), and by frequency of consumption of vitamin D-rich foods. P for linear trend was estimated using continuous 25(OH)D concentrations and vitamin D intake. ORs were adjusted for age, race, and smoking status. We further adjusted for hypertension status to examine if vitamin D status influenced early AMD via its effects on blood pressure.<br />

Results: The adjusted OR (95% CIs) for early AMD among those with adequate (≥75 nmol/L, n=2,402) compared to deficient (<30 nmol/L, n=465) vitamin D status was 0.94 (0.59-1.50), p-trend=0.90. Further adjustment for hypertension status did not influence results (OR [95% CI]=0.95 [0.59-1.52], p-trend=0.84). Results did not vary significantly by age, race, gender, early AMD subtype (soft drusen or retinal pigment epithelium depigmentation), or genetic risk. Early AMD was not associated with dietary vitamin D intake (OR [95% CI] for high [Q5] vs. low [Q1] dietary intake=1.24 [0.93-1.64], p-trend=0.38, visits 1 & 3 data averaged). Forcing supplement users of fish oils and vitamin D into Q5 only attenuated findings (1.17 [0.89-1.56], p-trend=0.38). Frequency of milk or fish consumption was not associated with early AMD.

Conclusions: Vitamin D status was not associated with early AMD in this biracial cohort.<br /> <br />