'Cancer risk warning' issued over daily use of Listerine Cool Mint mouthwash

Some scientists have raised concerns that daily use of Listerine mouthwash 'could increase the risk of some cancers'. Experts at the Institute of Tropical Medicine in Antwerp in Belgium investigated the daily use of the Cool Mint flavour mouthwash in a recent study.

They claim that daily use increased the level of two bacteria in the mouth that have been linked in the past to both colorectal and esophageal cancer - a claim rejected by Kenvue, the owners of Listerine. The Daily Telegraph reports that it is alleged the alcohol in the mouthwash may interfere with the normal level of bacteria in the mouth.

The study claimed that two kinds of bacteria - Streptococcus anginosus and Fusobacterium nucleatum - were much more prevalent after daily Listerine use for three months. They also claimed that there was a drop in a group of bacteria known as Actinobacteria.

These have been found previously to help with the regulation of blood pressure, they said. Listerine is approximately 20 per cent alcohol.

However, there are alcohol-free alternatives and the study recommends these. The scientists were assessing the impact of use of mouthwash on a daily basis on STI risk in 59 gay men before making these claims.

People taking part used Listerine on a daily basis for three months and then used a placebo mouthwash for a further three months, or vice versa. Professor Chris Kenyon, head of the STI Unit at the university and the study author, told The Telegraph: “Both organisms can cause severe invasive infections and have been linked to various types of cancer, such as esophageal and colorectal cancer.”

He warned that daily mouthwash use “could increase their risk of cancer and various infections”. He added: “Most people should not be using it and if they do use it, they should use the preparations without alcohol and limit the use to a couple of days.”

The study only tested Listerine. Yet the professor stressed the impact on bacteria would be likely to be witnessed with other alcohol-based mouthwashes.

The paper was published in the Journal of Medical Microbiology. In it, the authors wrote: “Listerine use was associated with an increased abundance of common oral opportunistic bacteria previously reported to be enriched in periodontal diseases, esophageal and colorectal cancer, and systemic diseases.

“These findings suggest that the regular use of Listerine mouthwash should be carefully considered.” Dr Jolein Laumen, first author of the study, said: “Alcohol-based mouthwashes are widely available. The public may use them daily to tackle bad breath or prevent periodontitis, but they should be aware of the potential implications.

“Ideally, long-term usage should be guided by healthcare professionals.” The Telegraph said that data on smoking and dietary habits were not collected. As a result, they said researchers were not able to account for these factors in the results.

A spokesman for Kenvue, which owns Listerine, said: “Kenvue welcomes and encourages scientific advancements and exchanges to promote everyday health. Based on our initial review, the published trial lacks several important design controls and adequate rigour to make any conclusions about potential impact to human health.”