Contribution of plasma folic acid and homocysteine levels to the mean carotid intima media thickness in smokers

The aim of this study was to investigate the effect of smoking on the atherosclerotic risk indicators, the independent risk factors for the plasma homocysteine, and for the mean carotid intima media thickness (mIMT) in the smoker and nonsmoker groups. A total of 213 male subjects, consisting of 96 smokers and 117 nonsmokers, were recruited. Smokers had significantly greater plasma triglyceride level (P = .016) and significantly lower plasma high-density lipoprotein cholesterol level (P = .004) than did nonsmokers. The mIMT and plasma homocysteine level of the smokers were significantly greater than those of the nonsmokers (P = .001 and P = .044, respectively). Multiple linear regression analysis showed that the plasma folic acid concentration was a significant contributor to the plasma homocysteine level in the smoker group (P = .018), and age was a significant contributor to the plasma homocysteine level in the nonsmoker group (P = .024). Age is a significant contributor to the mIMT in both groups (P = .001), and plasma homocysteine level contributed significantly to the mIMT in the smoker group (P = .001). These data suggest that low plasma folic acid status contributed to the high-normal homocysteinemia found in smoker subjects, and this might partially explain the increased mIMT observed in the smoker group.