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Geoffrey Kenneth Broadhead, Elvira Agron, David Peprah, Tiarnan D L Keenan, Traci E Clemons, Tom Lawler, Julie A Mares, Emily Y Chew; Dietary Nitrate Consumption And Risk of Progression in Age-Related Macular Degeneration. Invest. Ophthalmol. Vis. Sci. 2021;62(8):346.
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Purpose: To assess potential relationships between dietary nitrate intake and risk of progression in age-related macular degeneration (AMD).
Methods: Post hoc analysis of 2 large prospective clinical trial cohorts: Age-Related Eye Diseases Study (AREDS) and AREDS2. Dietary nitrate intake was calculated for each participant by analysis of food frequency questionnaire. AMD progression was evaluated by reading center grading of annual fundus photographs. Cox proportional hazard analyses were performed for AMD progression, according to quartiles of dietary nitrate intake (quartile 1 as reference), with adjustment for age, gender, smoking status, and caloric intake.
Results: In the combined AREDS/AREDS2 cohort (n=7788 eligible participants without late AMD in either eye at baseline), higher dietary nitrate intake was associated with decreased risk of late AMD (HR 0.80 for quartile 4, 95% CI 0.72-0.90). Risk of each late AMD subtype was also reduced, with both risk of geographic atrophy (GA; HR 0.78, 0.67-0.91) and neovascular AMD (NV-AMD; HR 0.61, 0.53-0.71) reduced. Similar associations were observed in each cohort, considered separately: HR 0.70 (0.59-0.83), 0.74 (0.60-0.90), and 0.73 (0.59-0.91), in AREDS, and 0.85 (0.74-0.97), 0.86 (0.70-1.06), and 0.88 (0.72-1.07), in AREDS2, respectively. In additional analyses of the AREDS cohort (n = 4288 eligible participants), adjustment was made also for dietary lutein/zeaxanthin intake (since this is correlated with nitrate intake); higher nitrate intake was still associated with decreased risk of late AMD (HR 0.68, 0.56-0.82), GA (0.67, 0.53-0.85), and CNV (0.73, 0.57-0.92). Also in the AREDS cohort, higher nitrate intake was also associated with decreased risk of progression to large drusen: HR 0.82 (0.68-0.99).
Conclusions: Higher dietary nitrate intake has protective associations against progression to late AMD. This is true for both subtypes of late AMD. Higher intake also appears associated with decreased risk of large drusen, so nitrate intake may be protective across the spectrum of AMD severity. The associations are independent of lutein/zeaxanthin intake, with which nitrates share some food group sources. These findings may justify further studies of nitrate supplementation, including randomized controlled trials.
This is a 2021 ARVO Annual Meeting abstract.
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