The detrimental effects of alcohol on health are widely known. Alcohol abuse is linked to several inflammatory pathologies, such as liver, intestinal and mental diseases (1).
When we consume alcohol, there is minimal absorption of alcohol in the mouth and oesophagus, approximately 20% of the alcohol consumed is gradually absorbed in the stomach, and 70% of the alcohol absorbed in the small intestine (2).
Because our gut comes into direct contact with the alcohol we ingest, it is in the alcohol-gut interaction that many of the pathologies associated with alcohol consumption originate; and it is here that our gut microbiota seems to play a relevant role (3).
How does alcohol abuse interact with our microbiota?
Our gut is home to the largest number of bacteria in our body, and under healthy conditions it forms a barrier that prevents these bacteria from being disturbed. When these bacteria are exposed to alcohol, this can lead to major health complications, as alcohol disrupts our gut barrier (3).
In fact, studies on alcohol abuse have shown that the gut microbiota of alcoholics is characterised by an enrichment of Proteobacteria and decreased levels of Bacteroides. In addition, increased levels of certain substances, such as plasma endotoxin and proinflammatory cytokines, among others, have been observed, reflecting damage to the intestinal barrier (4).
Furthermore, there is a strong connection between the gut and the brain. So changes in the functioning of the gastrointestinal tract, due to excessive alcohol consumption, can result in a multitude of cognitive changes and dysfunctions characterised by alterations in emotional processing, memory, executive functioning and goal-oriented behaviour (5).
But what happens if we consume alcohol in moderation?
Although some studies indicate that moderate alcohol consumption (up to one drink per day for women and up to two drinks per day for men) is not associated with adverse effects on cardiovascular diseases (6), future work needs to be done to establish the exact relationship between moderate drinking and these alterations in gut microbiota (7).
What is the message to remember?
If you consume alcohol, try to keep it in moderation. Alcohol abuse can lead to changes in your gut microbiota, affecting the gastrointestinal tract and your cognitive functions.
- Sæther, S.M.M.; Knapstad, M.; Askeland, K.G.; Skogen, J.C. Alcohol Consumption, Life Satisfaction and Mental Health among Norwegian College and University Students.Addict. Behav. Rep.2019,10.
- Lee, E.,Lee, J. Impact of drinking alcohol on gut microbiota: recent perspectives on ethanol. Current Opinion in Food Science and alcoholic beverage. 2021.37:91-97. DOI:10.1016/j.cofs.2020.10.001.
- Hammer, A.M., Morris, N.L., Earley, Z.M., Choudhry, M.A. The first line of defense: the effects of alcohol on post-burn intestinal barrier, immune cells, and microbiome. Alcohol Res 2015; 37:209–222.
- Tsuruya, A.; Kuwahara, A.; Saito, Y.; Yamaguchi, H.; Tsubo, T.; Suga, S.; Inai, M.; Aoki, Y.; Takahashi, S.; Tsutsumi, E.; et al. Ecophysiological Consequences of Alcoholism on Human Gut Microbiota: Implicationsfor Ethanol-Related Pathogenesis of Colon Cancer.Sci. Rep.2016,6.
- Whittier, A., Kumamoto, C. Gut Microbiome Dysbiosis in Alcoholism: Consequences for Health and Recovery. Front. Cell. Infect. Microbiol. 2022 Mar 3;12:840164. doi: 10.3389/fcimb.2022.840164.
- Chiva-Blanch, G., Badimon, L. Benefits and Risks of Moderate Alcohol Consumption on Cardiovascular Disease: Current Findings and Controversies.Nutrients2019,12, 108.
- Zhao, X., Zhou, R., 1, Li,H., Fan, Y., Sun, Y., 1, Hu, X., Zhang, S. The Effects of Moderate Alcohol Consumption on Circulating Metabolites and Gut Microbiota in Patients With Coronary Artery Disease. Front Cardiovasc Med. 2021 Nov 2;8:767692. doi: 10.3389/fcvm.2021.767692. eCollection 2021.