How Gut Health Affects Mental Health

What would you think if I told you that your gut health affects your mental health and vice versa? It may sound strange but it’s true. This isn’t woo-woo, it’s science, and it’s called the gut-brain axis. The study of the gut-brain axis is a relatively new area of science but it’s rapidly growing. 

The intricate relationship between the gut and the nervous system has become a hot topic and for good reason. Understanding how gut health affects mental health may help treat complex conditions like depression, anxiety, and even neuroinflammatory diseases like Parkinson’s and Alzheimer’s disease (1,2).

To understand how your gut affects your mental health, we need to look at the teeny microorganisms that are running the whole show—your gut microbiota. 

The gut microbiome affects your entire body!

Your gut microbiome is made up of trillions of bacteria, viruses, and fungi that live primarily in your large intestine or colon. Ideally, these microbes live with us in harmony. They help us synthesize important vitamins and nutrients, program and regulate our immune response, influence our metabolism, and protect the delicate lining of our gut. These tiny but mighty gut bugs do a freaking lot for our health, including the production and modulation of neurotransmitters. That’s right—neurotransmitters like serotonin, dopamine, and GABA are made in your gut (3).

Now, this is how it works when our gut flora is thriving and balanced. On the flip side, gut microbiota can become unbalanced. This disruption to gut homeostasis is called dysbiosis. 

Dysbiosis can lead to problems that manifest not only within the gut itself but throughout the entire body, including, you guessed it—the brain. So now that you know about this microscopic ecosystem within the gut, you can better understand how gut health affects mental health. 

Studies have shown that those with depression and anxiety have gut dysbiosis (4,5), whereas their healthy counterparts do not.

What’s more, researchers have found that when mice receive a fecal transplant (oh yeah, that’s a thing) of “depression microbiota” from humans with major depressive disorder, those mice develop depressive symptoms (6). 

In case you are wondering if you read that right, you did—researchers transplanted poop from people with depression into healthy mice, and then those mice became depressed. So, if unhealthy gut flora can manifest in feelings of depression, does this mean that a healthy and thriving gut ecosystem could heal and protect mental well-being? Research suggests that the answer is yes. 

Your diet directly affects your gut health. And because gut health affects mental health, what you eat influences your mental wellbeing (7). The power is in your hands. And your gut!

Eating foods that feed your good gut bugs helps ensure a thriving and diverse gut ecosystem. So what kind of foods do your gut microbes like best? Plant foods rich in polyphenols! Polyphenols are unique phytonutrients that have pretty amazing health benefits. They often act as antioxidants within the body, and your beneficial gut microbes love them. When your diet includes a wide variety of colorful plant foods, this means you are getting lots of polyphenols. These polyphenols help increase beneficial gut bacteria while reducing the overgrowth of bad gut microbes, preventing dysbiosis (8). (Turns out the old-school advice to “eat the rainbow” is 100% backed by science! Who knew?!)

Spices, herbs, and berries are fuel for your good gut microbes due to their high polyphenol content. Some foods contain outstanding levels of polyphenols: blueberries, black elderberries, black currants, strawberries, cherries, plums, globe artichokes, flaxseeds, olives, chestnuts, cloves, star anise, and oregano are all high on the list. You might be happy to hear that coffee and dark chocolate are also polyphenol superfoods (9). 

Not surprisingly, research has established a relationship between polyphenol-rich diets, like the Mediterranean diet, and mental health. This type of dietary pattern is associated with lower rates of depression and anxiety (10,11). 

A high-quality diet is also often rich in prebiotics, a particular type of fiber that your gut bugs love. Prebiotic-rich foods include garlic, onions, leeks, beans, and Jerusalem artichokes. Consuming five grams or more of prebiotic fiber each day can increase your good gut bacteria and reduce the risk of depression and anxiety (12). 

Fermented foods are also an excellent way to nourish your gut microbiota because they contain probiotics and essential vitamins and minerals. Studies have found that eating fermented foods may reduce social anxiety (13) and feelings of stress (4).  


The gut-brain axis means that your mental health also affects your gut health. Positive emotions, such as compassion, can increase the diversity of your good bug microbes (15).

On the other hand, feelings of loneliness have the opposite effect. Increased loneliness and less social engagement can reduce the diversity of good gut bugs, particularly as we age (15). 

Even though the research around gut health and mental health is still developing, it’s clear that making small changes to support a healthy gut can improve mood. Include a few gut-loving polyphenol-rich foods in your daily diet, try some yogurt or sauerkraut, and share some good chocolate and coffee with a friend. 

If you know your gut needs an overhaul, you’ll be happy to learn that I have a whole program devoted to gut health!

It’s called the Good Poopers Club and you can find out all about it by clicking the button below!