Love and attraction may be influenced by gut microbes

The mystery of love and attraction may not just be in our hearts. Scientists now think that gut microbes could be part of the story.

In a new study, researchers at Flinders University suggest microbes in our gut and environment may shape the hormones behind lust, attraction, and attachment.

Microbes may influence love

“We’re not claiming microbes ’cause’ love,” said Dr. Jake Robinson. “Our aim is to map plausible biological routes, grounded in microbiology and endocrinology, that researchers can now evaluate with rigorous human studies.”

Instead of searching for a single cause, the team looks at how microbes interact with the body’s hormone systems. These interactions may influence emotions linked with romance and even other states like aggression.

Lust involves testosterone and estradiol. Attraction is tied to dopamine and serotonin, while attachment depends on oxytocin and vasopressin.

These chemicals shape how people feel and connect. The review argues that microbes might tweak these hormones, changing how love plays out in real life.

Gut microbes, lust, and attraction

Gut microbes can alter testosterone and estrogen levels through the body’s hormone pathways. Microbial byproducts increase or decrease hormone availability, which may shift sexual desire.

When the microbiome falls out of balance, hormone activity suffers, sometimes lowering libido.

Attraction lights up the brain’s reward system. Dopamine surges, serotonin drops, and infatuation follows. Here too, microbes take part.

Around 95 percent of serotonin is made in the gut, where bacteria help produce it and send signals to the brain through the vagus nerve.

Even fruit fly studies show the link. Flies with different diets built different microbiomes and then preferred partners with the same microbial background. Antibiotics erased the preference. The microbes seemed to drive the choice.

Microbes influence bonding

Attachment keeps relationships going. Oxytocin, often called the cuddle hormone, plays a major role. Probiotics have been shown to increase oxytocin levels. Certain microbes also correlate with stronger oxytocin activity.

Vasopressin, another bonding hormone, may be influenced by microbes too. Experiments in animals show that gut bacteria can shift how vasopressin works in the brain.

Smell adds another layer. Some microbes release compounds that change how hosts perceive odors. That may alter how attractive someone seems.

Scientists call this the holobiont idea: humans and microbes acting together as one system. In this view, microbes influence choices that we think are entirely our own. This raises provocative questions about autonomy in human attraction.

Could subtle microbial shifts make us view one partner more favorably than another? Researchers suggest it is possible. If so, then relationships might partly reflect microbial influence, adding another hidden dimension to how people connect, bond, and choose mates over time.

Soil microbes may affect love

Dr. Robinson and colleagues also point to the environment. Healthy soils, for instance, release microbial signals and support vegetation that benefits our nervous and immune systems.

“As well as emitting important chemical and microbial signals, healthy soils support vegetation that improves air quality, buffer noise and moderate temperature to create immersive environments that affect our nervous, endocrine and immune system,” explained Professor Martin Breed.

When soils degrade, mental health may also suffer. Microbial richness falls, inflammation rises, and well-being declines.

Future research possibilities

“We are exploring how the evolutionary underpinnings of microbial-endocrine interactions could provide important insights into how microbes influence emotions beyond love, including hate and aggression,” said Dr. Robinson.

“If these pathways are confirmed, the findings could open avenues for microbiome-informed strategies to support mental health and relational well-being.”

Some researchers even imagine “green prescriptions” where exposure to nature supports emotional health. Others explore psychobiotics, probiotics designed to influence mood.

The concept is still young, but it shows how microbiology might one day connect with therapies for relationships.

Microbes help us understand love

The research doesn’t reduce love to microbes. It shows how biology, environment, and culture all overlap. Microbes may just be another piece in the puzzle.

For scientists, it opens new paths to explore. For the rest of us, it suggests love might be shaped by forces we rarely notice. It also reminds us that emotions are never isolated. They reflect a mix of chemistry, ecology, and lived experience.

Understanding this complexity could change how we think about relationships, health, and even the environments we build. Love may be personal, but it is also deeply biological.

The study is published in mSystems and Nature Cities.

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