Jan. 4 (UPI) -- Smoking regular cigarettes and vaping produces harmful health effects similar to just smoking cigarettes on their own, a study published Monday by the journal Circulation found.
Participants who smoked cigarettes and used both cigarettes and e-cigarettes had higher levels of inflammation and oxidative stress than those who did not use cigarettes or e-cigarettes, the researchers said.
People in the study who vaped exclusively also showed similar levels of inflammation and oxidative stress as those who did not smoke cigarettes or use e-cigarettes.
Inflammation and oxidative stress are key contributors to smoking-induced heart disease and have been shown to be predictors of heart attack and heart failure, among other health problems, the researchers said.
"[This study] has an important message for individuals who may believe using e-cigarettes while continuing to smoke some combustible cigarettes reduces their risk," co-author Dr. Rose Marie Robertson said in a statement.
"This commonly-seen pattern of dual use was not associated with lower levels of inflammatory markers, and thus is not likely to offer a reduction in risk in this specific area," said Robertson, deputy chief science and medical officer of the American Heart Association.
Cigarette smoking has long been linked with an increased risk for heart disease and death, although it appears to be on the decline, at least in the United States, according to the American Heart Association.
While use of e-cigarettes, or vaping, has grown in popularity, there has been limited research on its impact on health, the researchers said.
For this study, Robertson and her colleagues analyzed health data for more than 7,100 adults aged 18 years and older, focusing specifically on levels of inflammation and oxidative stress.
Oxidative stress is caused by increased production of free radicals -- unstable atoms that can damage the body's cells -- and the inability of the body to counteract or detoxify their harmful effects, the researchers said.
It has been linked with Parkinson's disease and Alzheimer's disease, gene mutations and cancers, chronic fatigue syndrome and heart and blood vessel disorders, among others, according to researchers.
Inflammation occurs when the body's immune system attempts to respond to a foreign pathogen.
Of the study participants, 59% did not use cigarettes or e-cigarettes, while nearly 2% vaped exclusively and 30% smoked cigarettes exclusively, the researchers said.
In addition, about 10% used both e-cigarettes and traditional cigarettes.
Compared to those who smoked cigarettes exclusively, people who vaped exclusively had significantly lower levels of inflammation and oxidative stress, the data showed.
However, participants who used cigarettes and e-cigarettes had levels of all inflammatory and oxidative stress biomarkers comparable to those who smoked exclusively.
The findings highlight the importance of continued public education regarding the risks of cigarette smoking and the failure of dual use to reduce risk, the researchers said.
"Some people who smoke cigarettes pick up e-cigarette use to reduce the frequency with which they smoke cigarettes, [and] they often become dual users of both products rather than switching entirely from one to the other," study co-author Andrew C. Stokes said.
"If e-cigarettes are used as a means to quit smoking, cigarette smoking should be completely replaced and a plan to ultimately attain freedom from all tobacco products should be advised," said Stokes, an assistant professor of global health at Boston University School of Public Health.