Abstract
Purpose :
There is growing evidence of the importance of nutrition in age-related macular degeneration (AMD). We previously reported the protective effects of a Mediterranean diet and dietary folate on risk of progression to advanced AMD (Merle BM et al. Am J Clin Nutr 2015; Merle BM et al. Am J Clin Nutr 2016). Few studies have evaluated the impact of vitamin D on AMD risk, and epidemiologic data related to this nutrient are sparse. We hypothesized that higher dietary intake of vitamin D could reduce transition to advanced stages of AMD.
Methods :
All participants were previously enrolled in our prospective epidemiologic studies of AMD. Among 2269 participants (4188 eyes), 552 (787 eyes) progressed from early and intermediate stages to advanced AMD (mean follow up: 8 years). Dietary vitamin D was collected at baseline using a validated food frequency questionnaire, and was log transformed and calorie-adjusted separately for men and women. Survival analysis was used to assess associations between incident advanced disease and dietary intake of vitamin D. Neovascular disease (NV) and geographic atrophy (GA) were also evaluated separately. The combined effect of vitamin D and calcium was assessed, with dietary intake of each nutrient defined as high (≥ median) or low (< median).
Results :
There was a significantly lower risk of progression to advanced AMD in the highest versus lowest quintile of dietary vitamin D intake after adjustment for demographic, behavioral, and ocular factors, as well as calcium, folate, monounsaturated fatty acids, EPA + DHA, and total energy intake (hazard ratio [HR]: 0.62; 95% confidence interval [CI]: 0.45-0.85; P trend=0.002). Similar results were observed for NV (HR: 0.61; 95% CI: 0.41-0.91; P trend=0.01), although the association with GA was not significant. A protective effect was observed for progression to advanced AMD among participants with high vitamin D and low calcium intake compared to the group with low levels for each nutrient (HR: 0.67; 95% CI: 0.50-0.88; P=0.005). There was no significant effect modification of dietary vitamin D by level of calcium intake.
Conclusions :
Our study suggests that high dietary vitamin D intake may reduce the rate of progression to advanced AMD, especially the NV subtype. Additional exploration is needed to elucidate the protective role of vitamin D and its potential contribution to the prevention of visual loss.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.