The Experiment Confirmed: Intestinal Fungus Affects The Attitude Towards Alcohol

The fungus Candida albicans, which thrives in the gut microbiome of people with alcohol addiction, may influence alcohol cravings in mice by affecting their dopamine signaling.

Experiments on mice were carried out at Tufts University. Their results, published in the journal mBioreliable and consistent – the problem is that directly generalizing them to people has proven impossible.

Experiments have shown that excessive growth Candida albicans — a fungus naturally present in the human intestine — increases levels of the inflammatory molecule PGE2, which can cross the blood-brain barrier and influence cravings for alcohol.

PGE2, or prostaglandin E2, is a multifunctional molecule involved in mediating inflammatory reactions, reducing gastric acidity and the development of fever. When C. albicans grows in the intestines—associated with antibiotics, poor diet, or alcohol consumption—the fungus simultaneously increases PGE2 production. Once in the forebrain, these molecules alter dopamine signaling in the dorsal striatum, an area responsible for reward processing and habit formation.

The researchers expected that mice colonized with C. albicans would find the taste of alcohol more attractive and therefore drink more – but the results were diametrically opposite: as PGE2 levels and the abundance of the fungus increased, the mice began to avoid alcohol. When the scientists blocked the PGE2 receptors, the behavior changed and the mice began drinking alcohol again.

“That’s how science works—our initial ideas were wrong,” admitted microbiologist Andrew Day, first author of the study. “This could be explained by differences in the response of mice and humans to C. albicans, differences in strains of the fungus, or we are not seeing the whole picture.”

They also found that mice with an overgrowth of C. albicans were more sensitive to the effects of alcohol on motor coordination. This effect was also reversed by blocking PGE2.

“Our bodies are designed to respond behaviorally to our gut microbiota, and this study highlights that fungi are important components of the gut-brain axis.” We believe that the level of fungal colonization in alcohol-dependent individuals may influence alcohol consumption by regulating interest in drinking. How this affects the enjoyment of drinking is more a matter of interpretation,” said Professor Carol Kumamoto, senior author of the study.

Namely, pleasure is the key difference in the connection of the dopamine system with drunkenness: in mice there is a decrease in the number of receptors Drd2 creates an aversion to alcohol, and in people, on the contrary, increases the risk of abuse.

So far, the study has raised more questions than it has clarified. Further research will provide answers to these questions, especially since preliminary encouraging results have already been obtained from trials of fecal microbiota transplantation for the treatment of alcohol use disorder.

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