Does cutting down on cigarettes lessen risks?

NEW YORK, Dec 19 (Reuters) Heavy smokers who cut down on cigarettes may actually do little to reduce their exposure to toxic tobacco compounds, a new study suggests.

Researchers found that a group of heavy smokers who cut down to as few as five cigarettes per day still inhaled many more toxic substances than people who were long-term light smokers.

The problem, say the researchers, seems to be that the former heavy smokers inhale more often and more deeply from each cigarette -- trying to get the amount of nicotine their bodies are used to.

This habit is known as ''compensatory'' smoking, and it may cut into any health benefits of reducing, rather than quitting, cigarettes, the study authors report in the journal Cancer Epidemiology, Biomarkers & Prevention.

''It is important for smokers to know that cutting down on cigarettes may not significantly improve their health risks,'' said lead author Dr Dorothy Hatsukami, a professor of psychiatry at the University of Minnesota in Minneapolis.

''The best way to reduce risk for disease is to quit smoking altogether,'' she told Reuters Health.

Hatsukami and her colleagues based their findings on a comparison of 64 formerly heavy smokers who had cut back and 62 light smokers. The heavy smokers had taken part in smoking-reduction studies and had managed to get down to five cigarettes a day, on average -- the same as the light smokers' levels.

To gauge the smokers' degree of compensatory smoking, the researchers measured their levels of a substance known NNAL, which indicates a person's exposure to a cancer-causing tobacco agent called NNK.

On average, the study found, NNAL levels were two to three times higher in former heavy smokers as they were in light smokers, even when they smoked the same number of cigarettes per day.

Hatsukami said the findings are consistent with what's been seen in studies of smokers' disease rates. That research suggests that people who cut their smoking by half lower their risk of lung cancer by no more than 25 per cent, and do not appreciably change their odds of other smoking-related ills, including heart disease and serious lung conditions like emphysema.

''It's a good explanatory factor for why you don't see a reduction in cardiovascular and pulmonary disease,'' Hatsukami said.

That doesn't mean there's no role for cutting back on cigarettes. Smokers who aren't ready to quit immediately can trim down their number of daily cigarettes as a first step, Hatsukami noted.

But that should be part of a path toward quitting, she said.