Vitamin intake: A possible determinant of plasma homocyst(e)ine among middle-aged adults

PURPOSE: Many epidemiologic studies have identified elevated plasma homocyst(e)ine as a risk factor for atherosclerosis and thromboembolic diseases. To examine the relationship between vitamin intakes and plasma homocyst(e)ine, we analyzed dietary intake data from a case-control study of 322 middle-aged individuals with atherosclerosis in the carotid artery and 318 control subjects without evidence of this disease. METHODS: All of these individuals were selected from a probability sample of 15,800 men and women who participated in the Atherosclerosis Risk in Communities (ARIC) study. RESULTS: Plasma homocyst(e)ine was inversely associated with intakes of folate, vitamin B6, and vitamin B12 (controls only for this vitamin)-the three key vitamins in homocyst(e)ine metabolism. Among nonusers of vitamin supplement products, on average each fertile increase in intake of these vitamins was associated with 0.4 to 0.7 μmol/L decrease in plasma homocyst(e)ine. An inverse association of plasma homocyst(e)ine was also found with thiamin, riboflavin, calcium, phosphorus, and iron. Methionine and protein intake did not show any significant association with plasma homocyst(e)ine. CONCLUSIONS: In almost all analyses, cases and controls showed similar associations between dietary variables and plasma homocyst(e)ine. Plasma homocyst(e)ine among users of vitamin supplement products was 1.5 μmol/L lower than that among nonusers. Further studies to examine possible caused relationships among vitamin intake, plasma homocyst(e)ine, and cardiovascular disease are needed.