Can Alcohol Cravings Be Explained by Gut Bacteria?

Researchers have been examining gut microbiota to figure out how it contributes to human health for a while now.

In fact, gut composition has already been linked to various health conditions, such as depression, allergies, obesity, and inflammatory bowel diseases.

Two Dreams uses evidence-based methods in developing our nutrition program and therefore encourage a varied diet to create diversity in gut microbiota. Our clinical staff works with each client to create a meal plan that reflects individual preferences and needs, so symptoms and afflictions are taken seriously. The ideal daily intake is portioned into quarters: 6.2 ounces of grain per day, 2.6 cups of green vegetables per day, 2.1 cups of colorful veggies or fruit per day, 3.1 cups of dairy per day, and 4 ounces of protein (6 ounces for males) per day. You can read more about the Two Dreams nutrition plan here ( /our-program/nutrition ) or call us at 501-510-2331 for more information.

In a recent study, Leclercq et al. looked at gut microbiota in heavy alcohol drinkers going through withdrawal and found a relationship between gut health and withdrawal symptoms.

The Contributions of the Gut Microbiota

One hundred trillion microbes constitute the average person’s gut. Their primary goal is to digest the food we eat in order to feed themselves and release the leftover byproducts to us. In doing so, they provide us with the nutrients and vitamins we need in our daily lives, and that’s not all they do!

Bacterial genes outnumber human genes approximately 360 to 1. They have a greater capacity to synthesize biochemicals to alter our behavior than we do, potentially through their synthesis of neuromodulators. They can also synthesize the neurotransmitters acetylcholine, dopamine, GABA, serotonin, and other molecules with neuroactive properties. The neuroactive compounds made by bacteria can interact with the enteric nervous system, and the coordinating neurons of the intestines, comprising the vagus nerve, transmit these messages to the brain.

Alcohol Makes the Intestines Permeable

Researchers have found that heavy drinkers have a tendency to develop alcohol liver disease, which is caused by leaky gut syndrome. Increased gut permeability allows the bacteria byproducts in the intestines to leak out into the body, causing immune system activation and inflammation. However, only 20% of heavy drinkers actually develop alcohol liver disease, suggesting the relationship between the disease and alcohol consumption is more complex.

In a recent study, scientists found that heavy alcoholic drinks could be split into two groups: those with low and those with high intestinal permeability. In their small group of 60 research participants, 43% had a highly permeable small bowel and colon that could be classified as leaky gut. The permeability had nothing to do with the level of alcohol consumption because both groups consumed similar amounts. Fortunately, gut permeability could be corrected. After 19 days of alcohol abstinence, gut permeability decreased to the level of nondrinkers in most participants.

Intestinal Permeability Affects Withdrawal Symptoms

People who had high gut permeability appeared to have a more difficult time with withdrawal symptoms. Although gut permeability was mostly restored to normal low levels, people who previously had leaky gut had worse depression, anxiety, and alcohol cravings three weeks after the start of sobriety than those without leaky gut. The participants with low gut permeability also did not start out with as high depression and anxiety scores and completely recovered in regards to their affective symptoms.




Alcohol Changes the Gut Microbiota

The bacterial composition of the gut is highly variable from person-to-person, but similarities have been found in groups of people with the same disease or similar health conditions. In the heavy alcohol drinkers with leaky gut, a number of differences in the microbial populations were observed. For instance, there was less of the good bacteria associated with healthy guts (Ruminococcaceae family members) and less of a bacteria known to reduce inflammation ( Faecalibacterium prausnitzii). They also had a lower total number of bacteria. Changes in other bacteria families and species were found, but the importance of these species was uncertain.

Quitting Drinking Alcohol Changes the Gut Microbiota

Just as quitting alcohol consumption restored the gut barrier, it led to the reconstitution of healthy gut bacteria (Ruminococcaceae family members) and the restoration of total bacteria number. Additionally, the Erysipelotrichaceae family bacteria (which might play a role in fatty acid metabolism and inducing inflammation) and the Holdemania spp. (healthy gut bacteria) decreased. These were the only notable changes though: F. prausnitzii and the other bacteria populations were not restored to the levels found in nondrinkers. Because removing alcohol did not restore these bacteria to normal levels, it is not known whether or not these bacteria are related to alcohol consumption, altered in drinkers for other reasons (dietary choices, ethnicity, diseases, genetics, etc.), or if not enough time was given to see a full recovery in the gut.

Do Microorganisms Make You Crave Alcohol?

Just like your body delivers messages to your brain telling you to eat when you are hungry (and sometimes even telling you what you are hungry for), bacteria in the intestines release biochemicals when they are low on nutrients, telling us to eat. It is unknown whether certain gut microbes can drive us to crave their favorite energy sources, such as high-fat foods or alcohol, though certain microbial populations were elevated in heavy alcohol drinkers with leaky gut {Lachnospiraceae, Incertae Sedis XIV, Dorea, Blautia, and Megasphaera.) After not drinking for three weeks, alcohol cravings in these people were unchanged, as were the concentrations of these bacteria. If microorganisms can participate in alcohol cravings, one of these aforementioned groups could potentially be responsible.

The Importance of Eating a Healthy Diet

More research is needed to substantiate if and how bacteria are influencing alcohol urges and addiction behaviors. It is already known that many people dependent on alcohol have poor diets, and that poor eating habits can drive cravings and promote relapse. Bacteria in the intestines of heavy drinkers are reduced in number, so drinking alcohol might directly kill the bacteria. However the bacteria might also be starving because of the poor diets of drinkers. The bacteria could just be signaling for more food consumption and drinkers mistaking food cravings for alcohol urges.

People undergoing drug addiction treatment should continue to make eating regular healthy meals a part of their treatment plan. Perhaps these studies on the gut microflora will, in the future, explain why eating better helps reduce drug/alcohol cravings and relapse.


Emeran Mayer. The mind-gut connection. How the hidden conversation within our bodies impacts our mood, our choices, and our overall health. New York, NY: HarperCollin Publishers, 2016.


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