The gut and the brain are intrinsically linked. To care for your digestion, then, is to care for your mental health — and vice versa.

The Mind and Gut Axis
The Mind and Gut Axis
| Credit: DeAgostini/Getty Images

Have you ever felt so excited you had "butterflies" in your stomach, or had a "gut feeling" something bad was about to happen? It's no surprise that so many metaphors about feelings start in the belly: after all, the gut and the brain are intrinsically linked.

"The gut microbiota is sort of a communicator or liaison between the enteric nervous system of our gut and the central nervous system of our brain," explains Ilene S. Ruhoy, MD, PhD, Gut Council Member for Jetson. And as clinical nutritionist and food entrepreneur Sharon Brown explains, this link begins in utero.

"There is one piece of tissue that splits - one part becomes the brain and one part becomes the gut."

For Jennie Malloy, Nutrititonist on behalf of beRevolutionarie, a digital wellness, fitness, and mindfulness platform for women, the gut could even be considered a "second brain."

"It contains hundreds of millions of neurons and produces neurotransmitters, like serotonin." In fact, about 90 to 95 percent of the body's serotonin is produced in the gut.

The gut and the brain are in constant communication by way of the vagus nerve, also dubbed the "brain-gut axis." And the ways in which they affect and influence one another are frankly extraordinary.

Good Mood Means Good Digestion

You may have already noticed that when you're under stress, you can experience digestive symptoms from stomachache to nausea to diarrhea. This is just one way in which the brain-gut connection makes itself known.

"The brain-gut connection is affected by stress and various emotions like anxiety, depression, and fear, which can affect the movements of the GI track, either increasing them or decreasing them," explains Dr. Marta Ra, CEO Paracelsus Recovery. "This change can cause bloating, pain, or change inflammation in the gut."

It's no surprise that stress can make digestion difficult.

"When we're under emotional stress," explains Dr. Erin Stokes, a naturopathic doctor and the medical director at MegaFood, our nervous system is likely to be in "sympathetic" mode, also known as "fight or flight" mode.

"It's challenging to digest food in this sympathetic state because our heart is racing, blood is being sent to muscles to face the challenge at hand, and digestion slows," she explains. "Conversely, parasympathetic mode is when we are in 'rest and digest' mode."

This is why experts often recommend eating in a relaxed state: away from screens, taking the time to sit and enjoy.

"If you eat in a stressed-out state, you won't be able to digest your food properly and the effects of this can be wide ranging - from gas and bloating to the development of allergies and even malnutrition," explains Brown.

Taking care of your mental health and attempting to reduce stress, therefore, can improve digestion and nutrient absorption and therefore general health and wellbeing.

Your Mental Health Is in Your Gut

While stress, anxiety, and depression can have a negative effect on digestion, the oppsite is true, too: what we eat affects our mood.

"If you've ever sat down to Thanksgiving dinner, or, perhaps a big bowl of pasta, and experienced a 'food coma,' then you know that what you eat can powerfully influence mood and state of mind," explains Brown. "This is the same for everything that we eat."

Foods that negatively impact gut health can negatively impact mental health as well.

"Eating too much sugar and simple carbs can lead to anxiety or depression," explains Andrea Trank, Certitied Halth Coach and Yoga Teacher. This connection, she explains, is linked to the producton of the stress hormone cortisol by the body.

"Many of these hormones are actually produced within the bacteria in your gut," she says. "If you are feeding the wrong kind of bacteria they will produce too much of these hormones."

Another culprit is candida overgrowth, explains Lisa Richards, nutritionist and author of The Candida Diet. Candida is a naturally occurring fungus that lives within the body, but when the gut's balance of candida is off, it can cause a host of health problems.

"Candida overgrowth can lead to symptoms like brain fog, confusion, difficulties with memory, and poor concentration," she explains, noting that candida overgrowth can suppress the production of mood-boosting serotonin.

"Dopamine is another neurotransmitter that affects your mood, and low dopamine levels are strongly associated with depression," she continues. "Candida has a role to play here too, as one of its metabolites (acetaldehyde) binds with dopamine. This, incidentally, is also one of the reasons why alcoholics tend towards depression."

Allergies and intolerances can lead to a wide variety of psychological symptoms, explains Brown, who cites fatigue, anxiety, irritability, weepiness, and/or hyperactivity.

"On the flip side," Brown continues, "when you eat whole, unprocessed, organic foods from nature that agree with your body you will have stable moods and energy and clear mental focus."

Some promising preliminary studies have shown that taking good care of your gut may improve mood disorders.

How to Improve Gut Health

To improve gut health, it's important to eat a good variety of gut-friendly foods.

"Food really is medicine to support mental health," says Kate Geagan, Pompeian's on-staff nutritionist and sustainable dieting expert.

This means consuming foods that keep blood sugar stable: colorful veggies, healthy fats, and clean proteins. Galvin notes the importance of whole foods with quality fiber, "the fuel source for bacteria."

"The more diverse plant based fibers you can eat, the better diversity you will have of your microbiome," she continues, "so eat veggies, fruit, nuts, seeds, beans and whole grains." Try recipes like this Zesty Whole Grain and Vegetable Salad or this Toasted Buckwheat Tabbouleh to reap these benefits.

Galvin also recommends consuming natural beef gelatin, which is rich in glycine and has been linked to improved brain function, reducing symptoms of OCD, and improving memory and attention. Try these Slow-Cooker Short Ribs for an easy way to include more natural gelatin in your diet.

Dr. Josh Axe, D.N.M., C.N.S., D.C., founder of Ancient Nutrition and, also recommends healthy fats like olive oil, avocado, and wild-caught salmon.

"Essential fatty acids are critical for brain health and help to support a positive mood," says Axe. "They contain protective antioxidants and help to reduce inflammation that can lead to gut health issues."

Geagan echoes this, noting that she is a big proponent of the Mediterranean diet, which features fruits, vegetables, whole grains, legumes, lean meat, fish, and olive oil, as in a classic Salade Niçoise.

"Researchers have found that people following this eating style (as opposed to a traditional Western diet) have significantly more types of beneficial bacteria in their gut, lower numbers of bacteria linked to inflammation, insulin resistance, and bowel cancer," says Geagan. "Further, researchers from various countries have found that a diet rich in EVOO can help fight and lower depressions rates and significantly improve mood and memory."

And of course, probiotics and fermented foods are excellent for gut health and therefore brain health.

"One of the best ways for people to positively impact their gut health is to eat more fermented foods like sauerkraut and kimchi," explains Paul, who recommends seeking out products with a label claim of "live and active cultures." You can also make your own sauerkraut and kimchi at home.

Other foods that have been shown to help improve mood, according to Ruhoy, include green tea, herbs like oregano and rosemary, cocoa, soup, sprouts, and dark chocolate.

It's also important to avoid foods that could be harmful to gut health, says Malloy, who cites dairy and gluten as prime culprits.

"If your gut is damaged from years of eating cronuts," she says, "it's going to impact your gut health and in effect, your ability to produce these feel-good neurochemicals."

By choosing, instead, healthful foods that promote good gut health and consuming them in a stress-free environment, you'll be setting yourself for improved gut and brain health all at once.

Check out our top-rated Microbiome Diet Recipes, for eating with a healthy gut in mind.