Cutting down on smoking cigarettes — even by as much as 50% — will not help you live longer.

Reducing consumption may serve as a useful milestone on the way to total smoking cessation, but the only real way to avoid the health consequences of smoking is to go all the way and quit completely, according to new research.

These findings, which appear in the December 2006 issue of the British journal Tobacco Control, are based on a study of more than 51,000 men and women, all of whom were aged between 20 and 34 at the start of the study.

Participants were initially assessed for cardiovascular risk factors, and classified as never smokers; ex-smokers, quitters; moderate smokers (1 to 14 cigarettes daily); reducers (more than 15 cigarettes a day, cut by more than half during the study); and heavy smokers (more than 15 cigarettes a day).

Among men, deaths from lung cancer and cancers associated with smoking were not significantly lower in those who had cut back compared with heavy smokers. But this was not true of women who cut back, where the reverse was true.

There were no significant differences in death rates from specific causes, including early death from cardiovascular disease, among women who cut back their daily consumption, compared with those who continued to smoke heavily.

The authors conclude that long-term monitoring provides no evidence that heavy smokers, who halve their daily cigarette consumption, significantly cut their risk of early death. They add that people may be misled if they are advised that cutting back will help them stave off disease.