The Brain-Gut Connection: How Gut Health Affects Mental Health


This article is part of a series on Nutritional Psychology and how what we eat affects our brains and moods. Nutritional Psychology is a relatively new field that emerged in pursuit of taking our time to examine and investigate the connections between what we eat and how we feel. Eating to maintain gut health plays a role in eating for mental health because of how nutrients affect mood and behavior. Read on to learn more about the gut-brain axis and which foods to eat for a healthy gut.

Neurotransmitter Basics

Our brain cells use chemicals called neurotransmitters to communicate with each other. These chemicals serve a variety of different purposes in our bodies and contribute to behavioral regulation. For example, dopamine plays a role in feeling rewarded and norepinephrine plays a role in response to stress by heightening arousal, increasing oxygen supply to the brain, and increasing focus.

The neurotransmitter serotonin helps set the tone for brain activity. It plays a role in our daily rhythm because it is involved in our daily functions, such as sleeping and digesting, and it interacts with our endocrine system and influences the production of other neurotransmitters, such as melatonin. Serotonin is also a mood regulator, which is why eating to maintain healthy serotonin levels is a part of eating for mental health.

How the Brain and the Gut Are Connected

The gut includes our entire gastrointestinal (GI) tract, from where food enters at the mouth to where waste exits at the end. It serves as the interchange system through which we interact with our environment by ingesting our food. The gut is like a big port, permitting certain substances in, allowing specific actions to occur, and passing waste along.

Millions of nerve cells and microorganisms (bacteria, archaea, and eukarya) line the gut and interact with each other to influence our moods and provide other benefits. The microorganisms of our microbiota are unique to each individual and help strengthen the muscle cells of our intestinal walls, aid in digestion, and support our immune systems.

Over 90 percent of serotonin is produced in our gut, either directly from the microbiota or through an interaction between the microbiota and nerve cells. Because serotonin influences so many regulatory functions and helps regulate our moods, maintaining a happy, healthy gut is part of eating for mood regulation.

What to Eat for a Healthy Gut and a Happier Mood

Tryptophan-rich foods

After ingestion and through interactions with gut microbiota, tryptophan is eventually turned into serotonin and other chemicals. Regularly consuming foods such as rice, soybeans, pumpkin seeds, walnuts, salmon, and dark, leafy greens will ensure you are getting enough tryptophan in your diet.

Omega-3 Fatty Acids

Salmon also provides omega-3 fatty acids, which interact with gut microbiota to maintain a strong intestinal wall and increase the production of anti-inflammatory compounds. You can find omega-3 fatty acids in other fish, such as mackerel, herring, sardines, and anchovies. Chia seeds, walnuts, and soybeans also contain omega-3 fatty acids, but they are ALA, which is less preferable to the EPA and DHA in fish.

Polyphenol-rich foods

These foods are thought to regulate our gut microbiota by decreasing the bad microorganisms and increasing the good ones. Foods highest in polyphenols include cloves, star anise, cocoa powder, Mexican oregano, celery seed, dark chocolate, flaxseed meal, and chestnuts. But you can also get some by basing your diet around a variety of whole fruits and vegetables and adding in seeds and nuts. You can also drink your polyphenols in both tea and coffee.

Fiber

This material in food helps keep the contents of our gut moving along. Bacteria in our gut also ferment fiber to produce butyrate, a chemical that helps maintain brain health. A diet that includes high-fiber whole grains also helps increase our gut microbiota diversity and decreases spikes in blood sugar that can lead to irritability and unpleasant moods. Get whole grains from rye, barley, brown rice, oats, millet, and popcorn.

Probiotics and Prebiotics

Probiotics increase gut microbiota diversity, and prebiotics help feed existing bacteria. Fermented foods such as sauerkraut, kimchi, miso, tempeh, and water kefir are all yeast- or bacteria-containing foods that add to your gut microbiota. Keep that microbiota strong by eating prebiotic foods such as chicory root, raw dandelion greens, leeks, onions, garlic, asparagus, spinach, bananas, and soybeans.

Eating a diet rich in whole foods that contain fiber, tryptophan, polyphenols, and both pre- and probiotics helps keep your gut happy. And a happy, strong, healthy gut means you’ll also have more regular moods. To learn more from this series, read about your brain on food and eating for depression and anxiety.