Cutting down can help quitting but doesn't cut death rates on its own
Smokers who cut down - but do not give up - are unlikely to reduce their chances of dying prematurely, a Scottish study has confirmed.
But experts stressed that cutting down can be a crucial step towards giving up altogether, which does cut the chances of premature death.
All of the participants were re-contacted a few years after they were recruited to the studies and asked again about their smoking habits.
Some had stopped altogether, some had reduced the number of cigarettes they smoked, while others had maintained or increased the level of their smoking.
All deaths were logged between the second screening and 2010, enabling the researchers to see whether there was any difference in the death rates between people who quit, people who reduced how much they smoked and those who maintained or increased how much they smoked.
The researchers found that quitters had lower death rates than those who maintained or increased how much they smoked, but there was no significant difference between those who cut down, and those who carried on smoking.
In one of the two studies, a sub-group of the reducers who had been among the heaviest smokers at the start did have lower death rates but this was not seen in the other study.
The new analysis, published in the American Journal of Epidemiology, do not support those of a similar long-term study in Israel where smoking reduction did appear to reduce death rates, but are consistent with larger studies of shorter duration in Denmark and Norway.
Professor Linda Bauld from Stirling University, one of the paper's authors said: "Our results support the view that reducing the number of cigarettes you smoke is not a reliable way of improving your health in the long term.
"However, what we do now know is that it may have a valuable role as a step toward giving up altogether - through cutting down to quit, an approach that has been recommended in recent guidance in the UK".
Cancer Research UK's Claire Knight said, "If you're a smoker, the best thing you can do for your health is to quit.
"Cutting down can help people who aren't currently ready or able to quit, but stopping entirely is important to start reducing your risk of the 14 types of cancer linked to smoking."
Copyright Press Association 2013