People who smoke menthol cigarettes may have a harder time butting out than those who light up non-menthol cigarettes, a new study suggests.

Menthol is a peppermint-based flavour that could potentially increase the harm caused by cigarettes, Dr. Mark Pletcher of the University of California, San Francisco, and colleagues proposed.

For a variety of historical and cultural reasons, including targeted advertising by the tobacco industry, about 70 per cent of black smokers in the U.S. use menthol cigarettes such as Newport, compared with 30 per cent among white smokers, the study said.

Pletcher's team hypothesized that if menthol cigarettes were more harmful than non-menthol varieties, it may help explain the disproportionately higher rates of cancer, cardiovascular disease and other smoking-related illnesses among African Americans, who tend to smoke less than European Americans.

"The bottom line for physicians and patients is that smoking is bad for your health, no matter what kind of cigarettes you smoke," Pletcher said."Per cigarette smoked, menthol cigarettes are no more or less harmful than non-menthol cigarettes. But our findings suggest that menthol smokers may need additional encouragement and support when they try to quit."

The researchers tracked 808women and 727 men over 15 years. Participants had medical exams and answered questions about their demographics and smoking habits in 1985 and then every five years.

About 69 per cent of people who smoked menthol cigarettes when the study began were still smokers in 2000, compared with about 54 per cent for non-menthol smokers.

"Among smokers who tried to quit, menthol seemed unrelated to quitting, but menthol was associated with a lower likelihood of trying to quit in the first place," the researchers wrote in Monday's issue of the Archives of Internal Medicine.

Menthol smokers who did quit were almost twice as likely to relapse and were also less likely to stop over a sustained period of time, the team found.

Two other measurements— the buildup of calcium in the arteries that is a sign of heart disease and a decline in lung function after 10 years— were linked to the number of cigarettes smoked but whether the cigarettes were menthol did not appear to make a difference.

The study did not determine why menthol cigarettes were harder to quit. The researchers speculated menthol cigarettes may increase breath-holding and decrease nicotine metabolism, raising levels of addictive nicotine in the blood, while the cooling effect of menthol may make the cigarettes more pleasant to smoke.