I live a healthy lifestyle except for one vice: I smoke one cigarette a day. Do my otherwise healthful habits negate the risks? —B.S., West Stockbridge, Mass.

Sorry, but no. Even "light" smoking (one to four cigarettes a day) increases the risk of heart disease and premature death in men and women, and it increases the risk of lung cancer in women, evidence shows. While less smoking is certainly better than more, strong research has found that it’s no match for quitting.

In a study involving more than 100,000 people, for example, the number of years spent smoking increased the risk of death from lung cancer more than the number of cigarettes smoked each day. The good news is that the less you smoke, the easier it is to stop. If you need help, the American Cancer Society offers free information about smoking cessation at 800-ACS-2345 or at www.cancer.org.