Study Finds Even Two Cigarettes a Day Can Significantly Raise Heart Disease Risk
A new long-term analysis is challenging common assumptions about “light smoking,” suggesting that even very small amounts of tobacco exposure may substantially heighten the risk of heart disease and premature death.
The research, published Tuesday in PLOS Medicine, followed more than 320,000 U.S. adults for nearly two decades. Johns Hopkins University scientists found that just two cigarettes per day or as few as 100 cigarettes across an entire lifetime were tied to markedly worse health outcomes.
Overall mortality was 60% higher among people who smoked at this low level compared with individuals who had never smoked. Their risk of developing heart disease was 50% higher, the study reported.
Cardiologists say the findings reinforce what decades of research have already hinted at: that even small doses of tobacco can undermine cardiovascular health.
“Tobacco use is a very well-established risk factor for heart disease,” said Dr. Jennifer Miao, a cardiologist at Yale University and an ABC News Medical Unit fellow.
“It really damages the blood vessel lining, and it accelerates the development of plaques and coronary artery disease.”
She noted that tobacco exposure is also associated with problems like atrial fibrillation and stroke.
One of the study’s most concerning observations is that simply reducing cigarette consumption didn’t appear to erase the long-term consequences. Current smokers faced the highest dangers, but even former smokers carried elevated heart disease risks in some cases, persisting more than twenty years after quitting.
Dr. Erfan Tasdighi, the study’s co-author and an internal medicine physician at Rutgers New Jersey Medical School, said the results should push clinicians to counsel patients toward full cessation, not merely reduction, because “no amount” appears safe.
“We actually have the evidence to say that even less than one cigarette a day can increase different multiple cardiovascular outcomes, and it’s not something that’s clinically insignificant.”
Despite dramatic drops in overall smoking rates in the United States, from about 42% of adults in 1965 to roughly 12% in 2022, according to the American Lung Association, the landscape of smoking has changed. The share of people who smoke fewer than 15 cigarettes per day has increased 85% over the same period, representing a growing group of “light smokers” who may underestimate their risks.
“In recent years, there has been an increase in the number of people who still smoke, but smoke less. As smoking patterns shift with more people smoking fewer cigarettes, it’s important to understand the cardiovascular risks of low-intensity smoking and the long-term benefits of quitting,” said study author Michael J. Blaha, M.D., M.P.H.
“This study, reflecting more than 320,000 U.S. adults over 20 years, gives us the statistical power to see relationships that other smaller studies cannot.”
These shifting patterns mean physicians must adapt how they evaluate tobacco exposure, the authors argued. Traditional metrics, such as the number of packs smoked a year, may overlook the dangers of intermittent or low-intensity smoking.
“Clinicians need a more nuanced approach that incorporates other ways to identify and quantify cigarette use, like smoking status and smoking intensity,” Miao said.
Still, experts emphasize the difficulty many people face when trying to stop smoking entirely.
“It’s very, very important for us as clinicians to acknowledge that it’s a lot easier said than done.”
Miao encourages physicians to identify smokers who are struggling and connect them with cessation medications, counseling services, and other evidence-based support.
The researchers reported that the benefits of quitting accumulate most dramatically in the first decade after cessation. Yet even as the body begins healing right away, it may take many years for former smokers to approach the risk levels of people who never smoked.
Tasdighi stressed that early improvements shouldn’t be underestimated. “It’s important that people know that when they stop smoking, their risk goes down immediately and significantly,” he said.
Miao agreed, saying the research’s biggest message is straightforward. “It’s important to quit smoking early on, and no amount of smoking is without risk and health consequences,” she said.
Moumita Basuroychowdhury is a Contributing Reporter at The National Digest. After earning an economics degree at Cornell University, she moved to NYC to pursue her MFA in creative writing. She enjoys reporting on science, business and culture news. You can reach her at moumita.b@thenationaldigest.com.
