Alcohol-based mouthwash may disrupt oral microbiome, leading to gum disease and certain cancers

By Staff 6 Min Read

  • Researchers report that alcohol-based mouthwash may contribute to different levels of oral bacterial populations that could increase the risk of certain gum diseases and cancers.
  • The researchers indicated that alcohol-based mouthwash should be carefully considered before using it on a daily basis.
  • They said people with dry mouth and other conditions might find that alcohol-free mouthwash works best for them.

Alcohol-based mouthwash might increase the risk of developing health problems such as gum disease and some cancers, including colorectal cancer.

That’s according to a study conducted at the Institute of Tropical Medicine in Antwerp, Belgium, and led by Jolein Lauman, a PhD student in the Department of Clinical Sciences.

The findings were published in the Journal of Medical Microbiology.

In their study, the researchers said they found a significant difference in the composition and number of bacteria in the participants’ oral microbiome after using alcohol-based Listerine Cool Mint mouthwash.

They reported that two species of bacteria were significantly abundant after using the mouthwash daily. Fusobacterium nucleatum and streptococcus anginosus have been linked to several diseases, including gum disease and esophageal and colorectal cancer.

The scientists also noted a decrease in a bacteria strain called Actinobacteria.

The researchers did not collect information on the participants’ dietary habits or smoking. They also were unwilling to state that the public should stop using alcohol-based mouthwash.

Participants used the Listerine mouthwash for three months and then a non-alcohol mouthwash for three months, or vice versa.

The overall purpose of the trial was to find ways to reduce the incidence of gonorrhea, chlamydia, or syphilis in men who have sex with men.

According to Alliance Dental, most mouthwashes found in pharmacies contain alcohol. These can cause a brief burning sensation in the mouth, an unpleasant taste, and a drying in the mouth.

The alcohol also destroys almost all the bacteria in the mouth — both the good and the bad.

Alcohol-free mouthwash does not destroy all the bacteria but creates a new balance of bacteria in the mouth.

Researchers said people with problems with dry mouth, such as those undergoing radiation treatment as a side effect of some medications, or who have medical conditions, such as diabetes or Sjogren’s syndrome, may prefer alcohol-free mouthwash. People who have a history of alcohol abuse and those with extensive dental restorations might also prefer alcohol-free mouthwash.

“Alcohol-based mouthwashes are widely available,” said Lauman in a press release. “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.”

Researchers reported that the use of the Listerine alcohol-based mouthwash showed an increase of opportunistic bacteria that can increase bacteria associated with periodontal disease, esophageal and colorectal cancer, and systemic diseases.

“We found that Listerine cool mint had an adverse effect on some beneficial bacteria,” said Chris Kenyon, PhD, a professor at the Institute of Tropical Medicine and one of the authors of the study. “For example, it decreases the abundance of the phylum Actinobacteria. Various Actinomyces species are part of the nitrate-reducing oral bacteria, which convert salivary nitrate to nitrite for further generation of the potent vasodilator nitric oxide, which is important for keeping blood pressure down. The nitrate-nitrite-nitric oxide pathway is an important mechanism linking the oral microbiome to cardiovascular health”.

The authors note that regular use of Listerine should be used with caution and careful consideration.

“It [alcohol-based mouthwash] may be safe to use for short periods, but based on our findings and other types of evidence, I would not recommend long-term use,” Kenyon told Medical News Today.

However, at least one expert says it’s important to remember that using mouthwash does not directly lead to cancer.

“Mouthwash with alcohol may be a contributing factor if someone is also a smoker, alcoholic, or eats unhealthily, but research doesn’t suggest this is the cause of cancer alone. You would also need extensive use of it,” said Dr. Eric Ascher, a family medicine physician at Northwell Lenox Hill Hospital in New York.

“The type of mouthwash you should use is based on specific dental needs, which can be discussed at a biannual dental checkup. This is determined based on your enamel (the layer that protects your teeth), as well as overall dental hygiene,” Ascher, who was not involved in the study, told Medical News Today.

“Researchers urge that the study results do not mean that the general public should no longer use mouthwash,” he added.

There were several limitations in the study that were listed.

  • Swabs of areas of the mouth were limited to tonsillar pillars and the posterior oropharynx. The authors note that the results may not represent the entire oral cavity.
  • Adherence to using the mouthwash was not controlled.
  • Changes were not confirmed with a second methodology.
  • Only men who have sex with men were included in the study. Therefore, the results might not be generalizable to the general public.
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