A refreshing gargle with Listerine’s Cool Mint mouthwash is a daily ritual for many, promising fresh breath and a cleaner mouth. However, a recent study published in the Journal of Medical Microbiology has cast a shadow on this common oral hygiene practice, suggesting it might be doing more harm than good.
The study found that regular use of Listerine could be linked to an increased risk of certain cancers and infections. Researchers discovered that daily usage of the popular mouthwash leads to an abundance of two species of bacteria – Fusobacterium nucleatum and Streptococcus anginosus – which have been linked to causing cancer. Fusobacterium nucleatum, a key player in periodontal disease, has been associated with colorectal cancer due to its ability to promote inflammation and tumour growth. This bacterium can invade tissues, potentially influencing overall systemic health. Meanwhile, Streptococcus anginosus, part of the Streptococcus anginosus group (SAG), is commonly found in the oral cavity and gastrointestinal tract. It is known for causing abscesses and invasive infections, especially in individuals with compromised immune systems.
The researchers believe that the alcohol in the mouthwash may contribute to the increased levels of these bacteria. Not only did it accelerate the growth of these harmful bacteria, but they also observed a decrease in a group of bacteria called Actinobacteria, which have previously been found to contribute to the regulation of blood pressure.
These shocking observations were made while studying the impact of daily mouthwash use on STI risk among gay men. The study involved 59 participants who used Listerine daily for three months followed by three months of placebo mouthwash or vice versa. Dr Jolein Laumen, the first author of the study, told The Telegraph, “These findings suggest that the regular use of Listerine mouthwash should be carefully considered. Alcohol-based mouthwashes are widely available, and the public may use them daily to tackle bad breath or prevent periodontitis, but they should be aware of the potential implications.”
While the study specifically focused on Listerine, Professor Chris Kenyon, a scientist at the Institute of Tropical Medicine in Antwerp, Belgium, who worked on the study, stressed that similar levels of bacteria would likely be found with other alcohol-based mouthwashes. Kenyon told The Telegraph, “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.”
Listerine contains around 20 per cent alcohol, which, according to The Sun, is not enough to destroy the odor-causing and decay-causing bacteria. Instead, it serves as a preservative ingredient and a carrier for the other active ingredients in the mouthwash. The study’s scientists recommend using alcohol-free alternatives, as they do not destroy all bacteria in the mouth but rather create a good balance.
Meanwhile, a spokesperson of Kenvue, the company behind Listerine, told the Daily Mail, “Based on our initial review, the published trial lacks several important design controls and adequate rigour to make any conclusions about potential impact on human health.”
