In research published in mBio, scientists found that Candida albicans, a fungus that naturally lives in the gut and is often overabundant in people with alcohol use disorder, can actually change how mice respond to alcohol. 

When the researchers colonized mice with excess C. albicans, the animals produced more prostaglandin E2 (PGE2), an inflammatory molecule known to trigger fever, suppress stomach acid, and influence immune signaling.

As PGE2 levels rose, the mice unexpectedly began avoiding alcohol. Instead of finding alcohol rewarding, they showed aversion. When the researchers blocked PGE2 receptors, the mice resumed normal drinking—confirming that this inflammatory pathway was driving the behavior. 

The team traced the effect to the dorsal striatum, a brain region involved in motivation and habit formation, where changes in dopamine signaling seemed to make alcohol feel harsher and less enjoyable.

This outcome differs from humans, where C. albicans overgrowth is typically linked to heavy drinking, not avoidance. 

The researchers suggest several possibilities: the aversion response might be an early evolutionary defense that becomes overridden in chronic drinkers, or it may be that in humans, drinking comes first, and the fungal bloom develops later as a consequence of alcohol’s impact on the gut.

Despite these differences, the study underscores a bigger theme: our behavior is closely tied to the health and balance of the gut microbiome.

“Our bodies are wired so that our behavior responds to gut microbiota, and this study highlights that fungi are important components of the gut-brain axis,” senior author Carol Kumamoto, a professor of molecular biology and microbiology at the School of Medicine said in a press release.

A healthy gut microbiome maintains balance—beneficial microbes keep harmful, inflammatory species in check, and together they support digestion, immune function, and mental well-being. But the system is fragile. Poor diet, stress, smoking, certain medications, and especially alcohol can disrupt this equilibrium.

Alcohol reduces microbial diversity and kills off beneficial bacteria, allowing inflammatory species to flourish. Over time, this imbalance contributes to intestinal permeability, commonly known as “leaky gut,” where toxins from the gut slip into the bloodstream and circulate throughout the body.

This triggers low-grade, chronic inflammation that doesn’t stay confined to the gut. Inflammatory molecules travel to the brain, contributing to neuroinflammation, which has been linked to irritability, anxiety, and trouble concentrating. It’s one reason people with alcohol use disorder may seem more on edge—even before drinking becomes severe.

So when you start noticing a drinking buddy becoming more sassy, snappy, or unusually stressed, it might not just be the alcohol, it could be their gut sounding the alarm.

In extreme cases, fungal overgrowth can become so pronounced that C. albicans ferments carbohydrates into ethanol inside the gut, causing auto-brewery syndrome, a condition in which a person becomes intoxicated without drinking.

Alcohol use disorder is a chronic but reversible medical condition defined by compulsive alcohol use despite harm. Repeated exposure to alcohol causes structural and functional shifts in the brain, particularly in reward, stress, and decision-making pathways.

Early in the cycle, alcohol triggers strong dopamine surges, creating feelings of pleasure and relief. 

Over time, the brain adapts, making it harder to feel the same buzz from the same amount of alcohol and making you more anxious, irritable, or uncomfortable when you’re not drinking. Impulse control weakens, anxiety rises, and judgment declines, creating a loop where alcohol is used to soothe the very discomfort it causes.

The gut microbiome appears to influence this cycle at multiple points. gut inflammation ramps up stress and anxiety in the background, pushing people to drink for relief rather than enjoyment. 

Microbial shifts can throw off dopamine and GABA, the brain chemicals that help you feel pleasure and stay calm. That combo can make alcohol feel less fun when you drink it, and more like something you ‘need’ when you stop.

The gut microbiome appears to influence this cycle at multiple points. Dysbiosis-driven inflammation amplifies stress and anxiety, pushing people to drink for relief rather than enjoyment. A disrupted gut–brain axis makes it tougher to think clearly or hit the brakes on urges, while strengthening stress-driven cravings, reinforcing dependence.

The new study offers a striking example of how deeply the gut can influence the brain’s response to alcohol—even if mice and humans don’t respond the same way. 

What the findings make clear is that alcohol use disorder isn’t just a brain condition or a behavioral issue; it is profoundly intertwined with the biology of the gut.

Understanding this connection may help people reshape their relationship with alcohol from the inside out.