Relation of blood homocysteine and its nutritional determinants to age-related maculopathy in the third National Health and Nutrition Examination Survey.

BACKGROUND: Blood homocysteine and its nutritional determinants folate and cyanocobalamin (vitamin B-12) have been shown to affect the risk of vascular disease. The pathogenesis of age-related maculopathy (ARM) is related to adverse vascular changes.
OBJECTIVE: The objective was to evaluate the associations between homocysteine, its nutritional determinants, and ARM in persons aged >or= 40 y participating in the third National Health and Nutrition Examination Survey.
DESIGN: A nonmydriatic fundus photograph of one eye, taken in a mobile examination center, was used to ascertain ARM status. Phlebotomy was performed for measurement of homocysteine, cyanocobalamin, and erythrocyte folate in participants of phase 2 of the survey (n = 3828). Logistic regressions were used to compute odds ratios and 95% CIs by quintile of serum analyte by using sample weights and jackknife replication methods to adjust for the complex survey design. The final analyses were adjusted for potential risk factors that influenced odds ratios.
RESULTS: Total serum homocysteine, red blood cell folate, and serum cyanocobalamin were unrelated to ARM in the overall sample. However, red blood cell folate was inversely related to one type of early ARM lesion (soft drusen) in non-Hispanic blacks.
CONCLUSIONS: ARM does not appear to be associated with homocysteine or its dietary determinants in this survey. There is a need for further investigation to rule out potential associations in subgroups with low folate status that may not have been detected because of the cross-sectional survey design.