Have you ever been so stressed out that your stomach hurt? Perhaps you were so worried or anxious that you vomited or had diarrhea. Even that nervous butterfly feeling you sometimes get is a sign that the balance of microbes in your gut is off balance.

You have a staggering 100 trillion microorganisms, or bacteria, living in your gastrointestinal (GI) tract. Although we tend to associate bacteria with germs, there are good and bad bacteria. Good bacteria kill disease-producing cells, build vitamins and hormones, and help break down food.

Researchers have long known that stress, anxiety, and depression reduce the presence of good bacteria in your gut, leading to gastrointestinal distress. But does it work the other way around?

Can the state of your gut affect your mental health?

Groundbreaking research is showing that it can. A study published in 2011 by the British Journal of Nutrition demonstrated that subjects reported a decrease in anxiety and depression after just one month of treatment with probiotics, live organisms that promote the growth of good bacteria in your GI tract.

The study summarized that “These results provide further evidence that gut microflora play a role in stress, anxiety, and depression, perhaps via the enteric nervous system as well as centrally…. Probiotics might offer a useful novel therapeutic approach to neuropathological disorders and/or as adjunct therapies in psychiatric disorders.”

Surprisingly, this thinking is not new. As far back as the late 1800s, scientists were aware of a link between the gut and mental health. It was believed that waste putrefaction in the intestines produced toxins that caused mental disorders. Treating patients with dietary probiotics, and a vegetarian diet, was successful in improving mental health.

Unfortunately, the theory, autointoxication, became associated with a few physicians who took the radical and risky route of removing the colon of mental patients. The whole idea was largely dismissed as unscientific and a source of quackery, until recently.

How does the bacteria in your gut affect your brain?

A 2019 study published in Bioscience Microbiota, Food and Health focused on the relationship between gut bacteria and the gut-brain axis.

The gut-brain axis refers to communication between the central nervous system (the brain and spinal cord) and the enteric nervous system (the neurons and cells throughout the GI tract).

That’s right — your brain and your GI tract communicate with each other.

The enteric nervous system, or GI tract, is often referred to as the “second brain” because it contains 100 million nerve endings, as many as the spinal cord. The bacteria in the GI tract send signals to the brain by way of the hormone cortisol, which is the body’s primary stress hormone.

In addition to communicating with the brain, good bacteria also produce 90% of the body’s serotonin, the neurotransmitter that regulates mood.

How can you grow the healthiest environment in your GI tract?

Supplements containing probiotics can be purchased at health food stores and pharmacies, but different brands contain different organisms and not all bacteria perform the same function, so it’s a hit-or-miss solution.

There is an easier, less expensive, holistic alternative: consuming a diet high in prebiotics.

Prebiotics come from fiber in your diet. Fiber is the star when it comes to controlling your gut health. Fiber, the non-digestible part of plant foods, ferments in your colon, producing good bacteria.

A whole food, plant-based diet is naturally high in fiber. Whole wheat, oats, nuts, greens, beans, lentils, artichokes, cabbage, onions, garlic, leeks, asparagus, and bananas are particularly good prebiotics.

Foods that are contradictory to good gut health include inflammatory foods such as animal protein, processed foods, foods containing high fructose corn syrup or artificial sweeteners, foods containing antibiotics, and fried foods.

If you are new to a high-fiber diet, increase your consumption of fibrous foods gradually and drink plenty of water. You may experience temporary stomach discomfort or bloating at first, but this will subside as your body adjusts and your gut microflora balances out.

References

1. https://digitalcommons.unl.edu/cgi/viewcontent.cgi?referer=https://www.google.com/&httpsredir=1&article=1154&context=usdaagresmag
2. https://www.caltech.edu/about/news/microbes-help-produce-serotonin-gut-46495
3. https://www.tandfonline.com/doi/full/10.1080/19490976.2017.1353849
4. https://www.pcrm.org/good-nutrition/food-and-mood