The Birds, The Bees… and The Microbes

The Birds, The Bees… and The Microbes

Intimate partners share microbes. While it’s (hopefully) not at the front of our minds when we’re having sex, both the penis and the vagina have a microbiome of their own. Sex is an opportunity for us to swap microbes. And if both partners are healthy, sex could increase alpha diversity which is associated with better health.1 If sex can help our microbiome, can our microbiome helps us have better sex?

Can our microbiome help us have better sex?

Before we jump to sex, let’s review love which often goes with sex. According to psychology, there are three basic stages of love: lust, attraction, and attachment.2

  • Lust, or sex drive, is ruled by the hormones estrogen and testosterone.
  • Romantic attraction, the infatuation stage of love, brings in our neurotransmitters, serotonin, norepinephrine, and dopamine.
  • Attachment, our ability to nurture healthy relationships, is primarily stimulated by oxytocin and vasopressin. Interestingly, oxytocin and vasopressin suppress areas of the brain associated with negative emotions.3 This may help us maintain long-term relationships.

It shouldn’t surprise anyone that the gut microbiome is related to our sex life.

It shouldn’t surprise anyone that the gut microbiome is related to our sex life. If someone has dysbiosis sex may be uncomfortable. Many things can lead to dysbiosis. While we often associate an upset gut (diarrhea or constipation) with something we ate, dysbiosis can be caused by medications, environmental toxins, stress, and alcohol.4 Let’s look at each of the stages of love with respect to the microbiome.


We spot that person across a crowded room. We make your way toward each other when, bam, the odor hits us. Unpleasant body odor and bad breath are caused by the microbiome. Specifically, microbes in the body are producing metabolites that stink. Halitosis (bad breath) Bacteroides forsythus, Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans and Prevotella intermedia are bacteria that have been shown to produce volatile compounds containing sulfur.5 Ever notice how rotten eggs smell, even small amounts of sulfur compounds lead to significant stomach-turning smells. Likewise, body odor is also related to the metabolites produced by microbes. Microbes on the skin such as Micrococcaceae, aerobic diphtheroids and Propionibacteria break down sweat into smelly compounds.<sup>5</sup> Without these microbes, sweat doesn’t stink at all.

A healthy microbiome with great alpha diversity not only makes us smell attractive, it also increases our sexual craving.

Perhaps the person we spotted across the room smells great, almost intoxicating. That likely means that they have a good diet, great gut and skin microbe composition, and good liver and kidney function (the liver and kidneys are responsible for breaking down the foul-smelling metabolites and secreting them).5 We’re attracted – and we gravitate toward them. Hormones, estrogen and testosterone, also contribute to that animal attraction. The microbiota regulates estrogen metabolism through the production of beta-glucuronidase.6 People with greater alpha diversity in their microbiome make higher levels of testosterone associated with a greater sex drive.7 Interestingly, different species of microbes are associated with higher levels of testosterone in men and women.7 In other words, a healthy microbiome with great alpha diversity not only makes us smell attractive, it also increases our sexual craving.

Romantic Attraction

Our libido is further extended through norepinephrine levels which causes our heart to race, our palms to sweat, and make us feel euphoric when we’re in the presence of that special someone. Norepinephrine is why we can stay up all night, memorize every detail about this person, and lose our appetite.8 Serotonin (95% of which is made in our gut by our microbes) makes us obsessed with this new partner. Research has shown serotonin levels in people who are newly in love rival those seen in people with obsessive-compulsive disorder.3 Our microbes must be working overtime!

Dopamine is the magic we feel. Dopamine, the reward neurotransmitter, puts us in a feel-good state and increases the estrogen and testosterone such that we crave sex. Dopamine is also involved in the satisfaction we feel from a darn good orgasm.9 We might call an orgasm a sexual reward. It’s interesting that dopamine is both made by the brain and the microbes in the gut.10 It’s possible that our gut health helps determine the strength of pleasure we feel – the amount of dopamine released – when we experience pleasure.


If all goes well, we settle into a comfortable love with our special someone. This form of attachment comes from oxytocin, the bonding hormone, and vasopressin, which is also involved in social behavior, sexual motivation and pair bonding.8 The neuroendocrine pattern of bonding has been studied in the prairie vole. Through this work, we’ve learned that sexual attraction and partner attachment seem to work together.8 Like serotonin and dopamine, oxytocin is also affected by our microbiome; Lactobacillus reuteri can upregulate oxytocin.11 The hormones and neurotransmitters combined with our microbiome help us prefer a specific partner and motivate us to attach ourselves to our mate.

All of this is to say, sex and love can be improved by a good microbiome.

Knowing these things may help us find ways to be closer to our mates. For example, if we’re in a long-term relationship, we know that oxytocin is the key to keeping that bond strong. While oxytocin doesn’t make us fall in love with someone, it does increase bonding in those who are already attached. In women, orgasm is a strong stimulator of oxytocin.12 Touching the skin, such as in a massage, can help build that bond.13 Kissing, cuddling, and sexual intimacy can further oxytocin expression. Post-coital cuddling, caressing, and shared intimacy is highly correlated with sexual satisfaction and healthy, happy relationships.14 And what are we doing when we are cuddling – skin on skin? We’re swapping more microbes!

All of this is to say, sex and love can be improved by a good microbiome. And a healthy microbiome can improve our sexual experience.

Learn more


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