Simply cutting back on smoking does not reduce mortality risk, according to a recent study published in the journal Tobacco Control (2006, vol. 15, no. 6).

Between 1974 and 1978, Norwegian researchers evaluated more than 51,000 men and women, ages 20 to 49. During the next 20 years, they screened the participants one or two more times, dividing them into six categories: never smokers, ex-smokers, quitters, moderate smokers (1 to 14 cigarettes per day), reducers (15 cigarettes per day or more initially, but then reduced by at least 50 percent upon final examination), and heavy smokers (15 cigarettes per day or more consistently).

Compared with the heavy smokers, reducers had no reduction in mortality risk. In fact, female reducers had higher death rates (from smoking-related cancer and other causes) than female heavy smokers. Ex-smokers (who quit before the study) and quitters (who quit during the study) both fared much better, with the lowest death rates, respectively, after never smokers.

The findings counter advice offered by some health educators, say the researchers. "Our study shows that heavy smokers who cut down their daily cigarette consumption by more than 50 percent did not reduce their risk of premature death," says study co-author Kjell Bjartveit, MD, PhD, MPH. "Often smokers have been advised, 'If you are unable to quit, cut down.' Such advice may give people false expectations. Our study proves that the only safe way out is to quit smoking entirely."