Submitted to: American Journal of Clinical Nutrition
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/20/2001
Publication Date: 4/1/2002
Citation: Interpretive Summary: Age-related maculopathy (ARM) is the most frequent cause of visual impairment in the elderly. Vascular disease is often associated with ARM and these two disorders share many risk factors, such as smoking, decreased estrogen levels, and higher intakes of saturated fats. Elevated plasma levels of the amino acid homocysteine are also strongly associated with risk of vascular disease, and homocysteine concentrations are dependent on blood levels of folate and vitamin B12. The purpose of the present study was to investigate the relationship between ARM and blood levels of homocysteine, vitamin B12, and folate concentrations. Data were obtained from persons aged 40 years and older who participated in phase 2 of the Third National Health and Nutrition Examination Survey. Photographs taken in mobile examination centers were used to ascertain ARM status. Blood samples were taken as part of NHANES III, permitting the measurement of homocysteine, vitamin B12 and folate. Total serum homocysteine, folate and vitamin B12 were unrelated to ARM in the overall sample. A marginally significant association between ARM and folate was observed after excluding people who used supplements. Folate was also associated with one of the early lesions seen in ARM in Afro-American subjects. ARM was not associated with homocysteine or its nutritional determinants in this survey, but the evidence from the analyses of subgroups and the cross-sectional survey design indicate a need for further investigation to rule out potential association in persons with low folate intakes.
Technical Abstract: To evaluate the associations between homocysteine and age related maculopathy in persons 40 years of age or older who participated in the Third National Health and Nutrition Examination Survey (NHANES III), a non-mydriatic fundus photograph of one eye, taken in mobile examination centers, was used to ascertain age-related maculopathy status. Phlebotomy was performed, permitting the measurement of serum homocysteine and cyanocobalamin (vitamin B,2) and erythrocyte folate in participants of phase H of the survey (n=3828). Logistic regressions were used to compute odds ratios and 95% confidence intervals by quintile of serum analyte, using sample weights and Jacknife replication methods to adjust for the complex survey design. Final analyses were adjusted for potential risk factors for age-related maculopathy that influenced odds ratios. Total serum homocysteine and its nutritional correlates, folate and cyanocobalamin were unrelated to age-related maculopathy in the overall sample. A marginally significant, inverse association with folate was also observed in the overall sample after excluding people who used supplements at the time of the examination. Folate was also related to one early age- related maculopathy lesion (soft drusen) in blacks. Age-related maculopathy does not appear to be associated with homocysteine levels or its dietary determinants in this survey. There is a need for further investigation to rule out potential associations in subgroups with low intakes that may not have been detected due to the cross-sectional survey design.