Heated Tobacco Harms Blood Vessels, Study Finds

Even a single session of heated tobacco use can trigger measurable changes in blood vessel function and damage to blood cells, a study has said, raising fresh concerns about products often promoted as less harmful alternatives to conventional cigarettes.

The study published in the European Journal of Preventive Cardiology found that otherwise healthy smokers experienced impaired artery function, a rise in systolic blood pressure and signs of oxidative DNA damage after using two heated tobacco sticks consecutively.

The findings challenge the perception that heating tobacco instead of burning it makes these products harmless to the cardiovascular system.

The study has particular relevance for India, where the government has maintained a ban on electronic cigarettes and related devices, including heat-not-burn products, under the Prohibition of Electronic Cigarettes Act, 2019. The government has said it is not considering relaxing the ban.

Researchers from University Medical Center Mainz in Germany studied 30 adult smokers, with an average age of 34, who were otherwise healthy. They measured participants’ blood pressure, blood vessel function and blood markers before and immediately after supervised use of two heated tobacco sticks with a heating device.

The researchers found that systolic blood pressure rose by about 3 mmHg. More importantly, blood vessel function declined by 11%, as measured through flow-mediated dilation, an ultrasound-based assessment of how well an artery expands when blood flow increases.

The ability of blood vessels to widen normally is important for cardiovascular health. Impaired function of the endothelium — the thin layer of cells lining blood vessels — is associated with processes involved in atherosclerosis, in which arteries become narrowed or hardened.

The team also detected changes in blood oxygen measurements, metabolic markers and signs of oxidative damage to DNA in blood cells. Oxidative stress occurs when reactive molecules overwhelm the body's ability to neutralise them, potentially damaging cells and their components.

“These products are not biologically inert,” said lead researcher Dr Lea Strohm, pointing to the vascular, metabolic and genetic changes observed after acute exposure.

The study, however, examined immediate effects after a single session. It cannot establish whether the changes persist, how much regular use increases the risk of heart attacks or strokes, or whether heated tobacco causes the same degree of harm as conventional cigarettes.

Heated tobacco products warm processed tobacco to produce an inhalable aerosol containing nicotine and other substances. Conventional cigarettes burn tobacco, generating smoke and a complex mixture of toxic chemicals.

The distinction has been central to claims that heated tobacco products may reduce exposure to some harmful substances. But lower exposure to certain combustion-related chemicals does not mean that the resulting aerosol is safe.

Nicotine can stimulate the nervous system, constrict blood vessels and raise blood pressure. Other aerosol constituents, including fine particles and reactive chemicals, may contribute to inflammation and oxidative stress. The new study did not isolate the effects of nicotine from those of other substances in the aerosol, so it cannot establish which component caused each observed change.

Co-author Professor Thomas Münzel said the findings reinforce concerns about the cardiovascular effects of nicotine-containing products, whether smoked, heated or inhaled through other devices.

Larger studies with longer follow-up are needed to establish the health consequences of repeated heated tobacco use. The immediate changes reported in this study should not be interpreted as proof of permanent injury, but they show that exposure can produce measurable biological effects even in otherwise healthy smokers.

India already faces a substantial burden of tobacco-related disease, including cardiovascular illness, cancer and chronic respiratory conditions.

Under the Prohibition of Electronic Cigarettes Act, 2019, India prohibits the production, manufacture, import, export, transport, sale, distribution, storage and advertisement of electronic cigarettes. Government guidance has also included heat-not-burn devices among products covered by restrictions on nicotine-delivery devices.

The researchers argue that public health policy should consider the risks posed by all nicotine-containing products, rather than assuming that products which do not burn tobacco are safe for the heart and blood vessels.