Context
Observational epidemiologic studies indicate a direct association between homocysteine concentration in the blood and risk of age-related macular degeneration (AMD), but randomized trial data to examine the effect of homocysteine-lowering in AMD are lacking.
Objective
To examine incidence of AMD in a trial of folic acid/vitamin B6/vitamin B12.
Design
Randomized, double-masked, placebo-controlled trial.
Participants
5,442 female health professionals aged 40 years or older with preexisting cardiovascular disease (CVD) or 3 or more CVD risk factors. A total of 5,205 of these women did not have a diagnosis of AMD at baseline and were included in this analysis.
Intervention
Participants were randomly assigned to receive a combination of folic acid (2.5 mg/d), vitamin B6 (50 mg/d), and vitamin B12 (1 mg/d), or placebo.
Main Outcome Measures
Total AMD, defined as a self-report documented by medical record evidence of an initial diagnosis after randomization, and visually-significant AMD, defined as confirmed incident AMD with visual acuity of 20/30 or worse attributable to this condition.
Results
After an average of 7.3 years of treatment and follow-up, there were 55 cases of AMD in the folic acid/B6/B12 group and 82 in the placebo group (relative risk [RR], 0.66; 95% confidence interval [CI], 0.47–0.93; p=0.02). For visually-significant AMD, there were 26 cases in the folic acid/B6/B12 group and 44 in the placebo group (RR, 0.59; 95% CI, 0.36–0.95; p=0.03).
Conclusions
These randomized trial data from a large cohort of women at high risk of CVD indicate that daily supplementation with folic acid/B6/B12 may reduce the risk of AMD.