Whole blood folate, homocysteine in serum, and risk of first acute myocardial infarction

High level of total homocysteine (tHcy) is a risk factor for coronary arter y disease (CAD), but the mechanism is not known. The serum concentration of tHcy, total cholesterol, high density lipoprotein cholesterol (HDL-C), and apolipoprotein A-I (apo A-I) and the concentration of folate in whole bloo d were measured in 107 patients with first acute myocardial infarction (MI) and 103 controls. The level of whole blood folate was lower and that of tH cy higher in cases than in controls. An increase of 50 nmol/l whole blood f olate was associated with an OR for MI of 0.75, and an increase of 5 mu mol /l tHcy with an OR for MI of 1.57. Correlations were observed between the l evels of whole blood folate and tHcy and between whole blood folate and alc ohol intake, and in MI cases, between tHcy, HDL-C, and apo A-I as well as b etween HDL-C and alcohol intake. The number of cigarette smokers was higher among cases than controls. In smokers, the level of tHcy was higher and th at of whole blood folate lower than in non-smokers. After adjustment for sm oking, the whole blood folate and tHcy-associated risks of MI became non-si gnificant. We conclude that smoking may affect folate status and tHcy level adversely. The risk of MI in smokers may at least partly be attributed to hyperhomocysteinemia or low folate. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.