Policymakers and consumers should be wary of claims that data from clinical studies proves Heated Tobacco Products (HTPs) are less harmful for health, according to the authors of a new study published in Tobacco Control.

Researchers from the Tobacco Control Research Group have spent four years examining the data from 40 clinical trials on the potential health effects of HTPs. The overall findings from these studies were judged to be inconclusive.

Tobacco companies claim that using HTPs can be less harmful than smoking cigarettes. HTPs heat tobacco to produce an inhalable aerosol. This differs from conventional cigarettes where tobacco is burnt and from e-cigarettes which contain nicotine but not tobacco.

An all-female group of researchers, led by Dr. Sophie Braznell, analysed data on the health harms of HTPs, specifically biomarkers of potential harm (indicators of physical effects or changes in the body). This is the first and largest examination of this particular data.

They found HTPs caused both harmful and beneficial effects compared to cigarettes, and beneficial effects in smokers were inconsistent. The effects of HTPs compared to e-cigarettes and quitting smoking were also unclear based on the limited available data. Concerns were also raised over study quality. The trials were very short, and most were conducted under unrealistic conditions. Of the 40 trials, 29 were conducted by tobacco companies, who have a vested interest in trying to prove HTPs are less harmful than cigarettes.

Co-author Dr. Jamie Hartmann-Boyce comments:

Quitting smoking is the best thing someone who smokes can do for their health. There is a large body of evidence on safe and effective ways to transition away from smoking, which makes the relative lack of robust scientific evidence on heated tobacco products particularly striking. Most of the studies of heated tobacco products are small and relatively short term – they don’t give us a clear picture of their effects.

The authors of the study have called for longer, unbiased clinical studies into the health effects of HTPs that are entirely independent of influence from the tobacco industry. Such studies would help regulators and customers make proper informed decisions about these products.

This research follows on from previous work examining the available clinical data on HTPs, in terms of quality and adequacy in assessing lung cancer risk, as well as research exposing tobacco industry attempts to influence science in order to create a favourable environment in which to sell its HTPs.

Lead author Dr Sophie Braznell comments :

While our findings do not rule out the possibility that HTPs are "reduced risk", they provide little support for such claims. In the context of the tobacco industry’s ongoing manipulation of science and targeting of youth, we should be sceptical of whether HTPs can help combat the tobacco epidemic or instead perpetuate it.

This work has also contributed to a new brief by STOP, a global tobacco industry watchdog, bringing together the latest evidence on HTPs.