Smoking cessation, but not smoking reduction, reduces plasma homocysteine levels.

BACKGROUND: Cigarette smoking has been associated with increased plasma homocysteine levels. Although hyperhomocysteinemia may mediate some of the adverse cardiovascular consequences of smoking cigarettes, the effects of smoking cessation and smoking reduction on homocysteine levels have not been evaluated previously. HYPOTHESIS: The purpose of this study was to determine the effects of smoking cessation and smoking reduction on plasma homocysteine levels. METHODS: Fifty-one healthy subjects who smoked 35.9 +/- 6.4 cigarettes daily were randomized to continue smoking, reduce smoking to 4-8 cigarettes daily, or to stop smoking. A nicotine inhaler and individualized counseling were provided as aids to smoking cessation. RESULTS: In subjects who quit smoking, homocysteine levels decreased by 11.6%, from 8.58 +/- 2.31 to 7.53 +/- 2.26 micromol/l (p = 0.013). Significant changes in homocysteine levels were not observed in subjects who reduced smoking or continued to smoke. CONCLUSION: A "harm reduction" strategy of reducing cigarette use may not be sufficient for reducing the vascular risk associated with smoking cigarettes.