Social smokers who only light up on special occasions may have some of the same risks for heart disease as people with a daily cigarette habit, a US study suggests.

For the study, researchers examined data on smoking habits, cholesterol levels and blood pressure for a nationally representative sample of 39,555 adults. Most people said they did not smoke, while roughly 17 percent were current smokers and about 10% were social smokers who did not have a daily habit but did regularly smoke in certain situations.

Compared with non-smokers, social smokers were more than twice as likely to have hypertension and 53% more likely to have elevated cholesterol, the study found. Social smokers had the roughly the same odds of having these heart disease risk factors as current smokers in the study.

Every cigarette you smoke does your body damage. For someone predisposed to cardiac disease, exposure to cigarette smoke stresses the heart and increases the risk of serious cardiac problems.

"These results provide strong evidence that smoking, regardless of amount, is an even stronger indicator of cardiovascular risk than previously thought," said a researcher at the Ohio State University College of Nursing in Columbus and lead study author, Kate Gawlikr.

"Social smoking is still a major cardiovascular health risk," Gawlik said. "No amount of smoking is safe."

Researchers defined cardiovascular health based on blood pressure and total cholesterol levels. And before accounting for other factors like weight, age, gender and race or ethnicity, social smokers were found to have lower rates of hypertension than current smokers.

But after adjusting for the other risk factors, rates of hypertension were similar for current and social smokers, 76% and 75%, respectively, a difference too small to rule out the possibility that it was due to chance.

High cholesterol rates were also similar after adjusting for other risk factors: 53% for social smokers and 55% for current smokers.

Social smoking was most common among adults 40 and under, researchers reported online in the American Journal of Health Promotion. Social smokers were also more likely to be male and Hispanic.

Study participants were screened from 2012 to 2016 as part of a cardiovascular health education program. Participants reported their own smoking habits and had clinicians check their blood pressure and total cholesterol.

The study cannot prove whether or how much social smoking impacts heart health compared to other patterns of tobacco use. It also did not assess the long-term health effects of smoking, only the presence of certain risk factors for heart disease.

Another limitation of the study is that researchers lacked data on prior smoking behavior, the authors note. Participants also volunteered to join the study instead of being randomly selected, which might make the results less reliable.

It is also possible that not all of the participants had chronic high blood pressure, said co-leader of the tobacco research program at the Medical University of South Carolina in Charleston, Michael Cummings. That is because blood pressure readings may spike after someone smokes without being regularly elevated when they are not using nicotine, Cummings, who was not involved in the study, said.

But that does not make any amount of smoking safe, Cummings said.

"Every cigarette you smoke does your body damage," Cummings added. "For someone predisposed to cardiac disease for whatever reason, exposure to cigarette smoke stresses the heart and increases the risk of serious cardiac problems."

Heart problems associated with smoking do not need to be permanent, however, said director of the Center for Tobacco Control Research and Education at the University of California, San Francisco, Dr Stanton Glantz.

"Any smoking is bad," Glantz, who was not involved in the study, said. "The good news is that, unless the smoking has caused a heart attack, the effects go away when you stop."

Sign up to our free newsletters

Get the best updates straight to your inbox:
Please select at least one mailing list.

You can unsubscribe at any time by clicking the link in the footer of our emails. We use Mailchimp as our marketing platform. By subscribing, you acknowledge that your information will be transferred to Mailchimp for processing.