What A Week of Holiday Drinking Does To Your Gut Health — And How To Reverse It

‘Tis the season to throw back some bubbly. For some of us, the most wonderful time of the year is synonymous with stress, anxiety, and depression, what’s referred to as the holiday blues, resulting in coping mechanisms like imbibing more alcohol.

As we ease into a dry (or damp, if you can’t go cold turkey) January, here’s something to consider: too much booze could wreak havoc on your gut microbiome. Excessive drinking disrupts this delicate ecosystem of microbes residing in your gut, causing a slew of health issues, and may even encourage you to drink more by “reprogramming” your gut microbiome, some studies find.

Why is the gut microbiome important, again?

At this point, we’re probably familiar with the microbiome, but here’s a brief recap.

Our bodies, both inside and out, are flush with a patina of microbes — fungi, bacteria, protozoa (aka parasites), and viruses — that we’re born with or accumulate during our lifetime. While we often refer to this community of a trillion strong as the microbiome, the correct scientific term is the microbiota, as the former refers to all the genetic material carried by these microbes.

These generally “friendly” house guests play a key role in our everyday health, such as helping with digestion, regulating our immune systems, and influencing our mental health, even personality. When microbial harmony is disrupted — called dysbiosis — for whatever reason, such as with antibiotic use, a nutrient-poor diet, or aging, persisting imbalances may lead to chronic inflammation, contributing to conditions like Alzheimer’s disease, cardiovascular disease, and cancer.

Your gut on alcohol

When it comes to drinking alcohol, there are some microbial benefits, but those are tempered by a litany of negative health effects. For example, one 2022 study found that drinking beer — a lager sized at just over a pint containing 0 to 5.2 percent alcohol content — daily for four weeks may improve the biodiversity of one’s gut microbes. This appeared to be largely connected to antioxidants like phenols and postbiotics (chemicals produced by bacteria after digesting fiber) contained in beer. Another 2020 study published in the journal Gastroenterology found a similar benefit with moderate red wine consumption.

Undeniably, however, alcohol is hard on the gut — as anyone with alcohol-induced diarrhea can attest firsthand. Booze directly irritates the sensitive lining of the digestive tract due to its ethanol content, not unlike rubbing alcohol on your skin.

This irritation does a couple of things. It kills off gut bacteria indiscriminately, creating that imbalance that depletes beneficial “good” bacteria in favor of more hardy, rowdy “bad” bacteria. Engaging in excessive alcohol use, this imbalance can lead to a maelstrom of inflammation that might make the intestinal wall more permeable, much like chipping away the mortar in a brick wall. This makes room for pro-inflammatory bacteria or their toxins to escape into the rest of the body.

One 2014 study found that among otherwise healthy adults who binge drink (characterized as heavy alcohol consumption within a short period of time, according to WebMD), bacterial toxins and DNA were present in their blood within 30 minutes. This finding was higher among women compared to men, likely because of the differences in alcohol metabolism between the sexes.

Other studies in mice have found that alcohol negatively affects the gut microbiome by way of the liver. Our livers are detoxing machines; in response to bottomless mimosas, this lobed organ will break down alcohol into two chemicals: acetaldehyde and acetate. A 2022 study published in the journal Nature Communications found that in mice, acetate appeared to cause bacterial overgrowth since the chemical eventually transforms into carbon dioxide, where, in the gut, it’s basically microbe fertilizer. Prior studies have found that moderate alcohol consumption can lead to small intestinal bacterial overgrowth (or SIBO), a condition that can limit gut motility and cause symptoms of bloating and chronic diarrhea.

Lastly, microbial reshuffling after many a pub crawl may have you craving more. In a March 2023 study published in the journal eBioMedicine, part of The Lancet, researchers in Ireland found that among young people who engaged in binge drinking, they exhibited changes in their gut microbiomes that were associated with higher alcohol cravings over time alongside cognitive issues like not recognizing emotions well. The microbiome’s influence over the brain isn’t surprising: Gut bacteria have been shown to produce neuroactive chemicals and send signals through the gut-brain axis.

Resetting your gut health

If you are ready to boost your gut health, there are easy steps you can take. Alcohol is a known carcinogen, and its health benefits are hard to quantify, Dan Malleck, a medical historian specializing in drug and alcohol regulation and policy and professor in the Department of Health Sciences, previously told Inverse. While there are recommendations for safe alcohol consumption, it’s difficult to say what exactly is such an amount, even with the microbiome in mind.

Your best bet is to reduce, if not totally eliminate, how much you imbibe and incorporate a healthy, fiber and nutrient-rich diet that encourages a happy gut microbiome.

As a new year descends upon us, there’s maybe no better resolution than cutting back on the Aperol spritzes for a healthy microbiome.