Heavy smokers likely to be impotent

Smoking may increase a man's risk of impotence by almost 40%, The correlation shows up in men who smoke more than a pack a day. Smoking up to 20 cigarettes a day correlated with a 24% increase in impotence. Data can be explained by nicotine and other related chemicals diminishing blood flow to the penis and blood pressure in it. However here is the good finding: moderate alcohol consumption significantly reduced the risk of impotence.

Source : Tobacco Control