Mouthwash vs Microbiome: The Effects of Antimicrobial Mouth Rinses on the Oral and Gut Microbiomes

The relationship between our oral and gut microbiomes is a growing area of research, offering new insights into how these communities shape health and disease. Emerging evidence is revealing how everyday oral hygiene practices, like antibacterial mouthwash use, affect this balance.

What We Know:

• The gut and oral microbiomes are among the body’s largest microbial ecosystems, comprising 29% and 26% of the total bacterial count, respectively. Despite their distinct environments, their two-way connection - the ‘oral-gut microbiome axis’ - facilitates the exchange of microbial signals and metabolites that influence digestion, immune responses and systemic health. Disruptions in this axis have been linked to gastrointestinal disorders, cardiovascular diseases, among others, underscoring its vital role in maintaining overall health (Carvalho et al., 2024). 

• Although these microbiomes are distinct - due to barriers like gastric acidity and bile - oral bacteria may sometimes bypass these defences and migrate to the gut, influencing the gut microbiome and potentially contributing to diseases such as inflammatory bowel disease (IBD), colorectal cancer and systemic inflammatory conditions (Kunath et al., 2024).

Industry Impact and Potential:

• Prolonged use of antibacterial mouthwash has been shown to disrupt the oral microbiome. A study on Listerine Cool Mint found that daily use for three months increased levels of Fusobacterium nucleatum and Streptococcus anginosus. These opportunistic bacteria are linked to periodontal disease, systemic illnesses and even oesophageal and colorectal cancers. Moreover, oral bacteria that bypass the gut’s barriers may trigger systemic inflammation, compromising immune function and contributing to chronic diseases (Laumen et al., 2024).

• Research on chlorhexidine mouthwash in mice revealed notable changes in gut health, including reduced microbiome diversity, impaired nutrient absorption, and altered metabolism. While outcomes like decreased weight gain may initially appear beneficial, they are likely a result of malabsorption, which can have harmful downstream effects (Carvalho et al., 2024).

• These findings highlight the need to explore the oral–gut microbiome axis further, particularly the role of the oral microbiome in gut function and nutrient absorption. This opens new possibilities for developing oral hygiene products that maintain oral microbiome integrity while safeguarding the gut microbiome, paving the way for innovative solutions that support holistic health.

Our Solution:

At Sequential, we lead microbiome product development and testing from our hubs in London, New York and Singapore. We help businesses create products that preserve microbiome integrity while achieving efficacy. Partner with us to develop cutting-edge oral hygiene solutions that target the oral-gut microbiome axis and advancing health outcomes.

References:

Carvalho, L.R.R.A., Boeder, A.M., Shimari, M., Kleschyov, A.L., Esberg, A., Johansson, I., Weitzberg, E., Lundberg, J.O. & Carlstrom, M. (2024) Antibacterial mouthwash alters gut microbiome, reducing nutrient absorption and fat accumulation in Western diet-fed mice. Scientific Reports. 14 (1), 4025. doi:10.1038/s41598-024-54068-y.

Kunath, B.J., De Rudder, C., Laczny, C.C., Letellier, E. & Wilmes, P. (2024) The oral–gut microbiome axis in health and disease. Nature Reviews Microbiology. 22 (12), 791–805. doi:10.1038/s41579-024-01075-5.

Laumen, J.G.E., Van Dijck, C., Manoharan-Basil, S.S., de Block, T., Abdellati, S., Xavier, B.B., Malhotra-Kumar, S. & Kenyon, C. (2024) The effect of daily usage of Listerine Cool Mint mouthwash on the oropharyngeal microbiome: a substudy of the PReGo trial. Journal of Medical Microbiology. 73 (6). doi:10.1099/jmm.0.001830.