Commonly used alcohol-based mouthwash brand disrupts the balance of your oral microbiome, scientists say

05 June 2024

Hand of man Pouring Bottle Of Mouthwash Into Cap.jpg

  • Researchers have identified a significant change in composition and abundance of bacteria in study participants’ oral microbiomes after using a popular brand of alcohol-based mouthwash.
  • The oral microbiome is the community of bacteria that live in the mouth, they help us digest our food and keep our mouth healthy.
  • Researchers found that two species of opportunistic bacteria were significantly more abundant in the mouth after daily use of the alcohol-based mouthwash, Fusobacterium nucleatum and Streptococcus anginosus.
  • These two bacteria have been previously linked to several diseases including gum disease and oesophageal and colorectal cancers.
  • Although results show potentially damaging alterations to the microbiome, researchers urge that the study results do not mean that the general public should no longer use mouthwash.

The oral microbiome is the community of bacteria that live in the mouth, they help us digest our food and keep our mouth healthy. Changes to the composition of the oral microbiome have been linked to periodontal diseases and some cancers.

The research, published in Journal of Medical Microbiology is a follow-up to a larger study investigating the use of mouthwash as a method to reduce the transmission of sexually transmitted diseases in men who have sex with men. Researchers wanted to explore further and investigate whether the mouthwash used had an impact on the oral microbiome of the patients.

Researchers from the Institute of Tropical Medicine in Antwerp, Belgium found that two species of opportunistic bacteria were significantly more abundant in the mouth after three months of daily use of the alcohol-based mouthwash, Fusobacterium nucleatum and Streptococcus anginosus. These two bacteria have been previously linked to gum disease, oesophageal and colorectal cancers. Researchers also saw a decrease in a group of bacteria called Actinobacteria which are crucial contributors to the regulation of blood pressure.

Dr Jolein Laumen, first author of the study and researcher at ITM’s Unit of Sexually Transmitted Infections 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”.

Professor Chris Kenyon an author of the study and Head of the Unit of Sexually Transmitted Infections said:

“Up to half of men who have sex with men report using mouthwash for oral hygiene. This study adds to the literature that this is likely having an adverse effect on their oral microbiomes”.

While the results link the daily use of alcohol-based mouthwash to alterations of the oral microbiome, researchers are reluctant to draw substantial conclusions from the data. Information on dietary habits and smoking was not collected so researchers were unable to account for this in the analysis. As the small sample group was taken from the initial study, the results of this study may also not be representative of the population as a whole. Further research should examine how the detected changes affect clinical outcomes on larger and more representative sample groups.


NOTES FOR EDITORS

The paper ‘The effect of daily usage of Listerine Cool Mint mouthwash on the oropharyngeal microbiome: a substudy of the PReGo trial’ by J.G.E. Laumen, C. Van Dijck, S.S. Manoharan-Basil, T. de Block, S. Abdellati, B.B. Xavier, S. Malhotra-Kumar and C. Kenyon, published in Journal of Medical Microbiology under the following:

DOI: 10.1099/jmm.0.001830

URL: https://www.microbiologyresearch.org/content/journal/jmm/10.1099/jmm.0.001830 

About the Microbiology Society

The Microbiology Society is a membership charity for scientists interested in microbes, their effects and their practical uses. It has a worldwide membership based in universities, industry, hospitals, research institutes, schools, and other organisations. Find out more at microbiologysociety.org.

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About the Institute of Tropical Medicine

The Institute of Tropical Medicine (ITM) in Antwerp (Belgium) strives for the advancement of science and health for all, through innovative research, advanced education, professional medical services and capacity sharing with partner institutions in Africa, Asia and Latin America. For us, scientific excellence and societal impact are two sides of the same coin. www.itg.be

ITM experts in Transmission, a podcast on global health

You can hear more from Chris Kenyon in the Transmission podcast. Transmission is the award-winning podcast of the Institute of Tropical Medicine in Antwerp. Our enlightening and intimate series shares the personal and professional experiences of researchers and physicians as they relentlessly battle diseases.


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