← Back to portfolio

What's Inside You: The Connection Between Gut Flora and Mental Health

Published on

This article was originally published in Issue 10 of The Academic.

When you think of flora, you may think of forests or gardens. However, flora also refers to bacteria and other microorganisms that inhabit certain parts of your body. Flora can be found on the skin or in any body part that has a mucous membrane, including the nose and throat. Despite sometimes being classified as harmful bacteria, these microorganisms do not necessarily cause disease and are especially important in the large intestine where bacteria aids in the compaction and absorption of waste products. Gut flora may seem to be unrelated to mental health, but in reality, there is a strong connection between the two.

The Science of the Stomach

The flora found in the gastrointestinal tract helps to boost the immune system and produce vitamins, which are essential for good health. This may explain why having an illness, especially a chronic illness, can negatively impact your energy and disposition. Recently, researchers discovered that there is a greater link between gut flora and psychiatric disorders such as anxiety disorders and depression.

A healthy gastrointestinal tract has been associated with a healthy nervous system before (Clapp et al., 131), but emerging research suggests that there is a relationship between an unhealthy gut and the development of mental health issues. There is no “normal” distribution or collection of microorganisms in the human body, but people seem to benefit from having multiple types of bacteria in their body. Different microorganisms are introduced by eating different types of foods. For example, people who eat a lot of a certain nutrient, like protein, have certain kinds of bacteria dominating their large intestine. It is not bad to have a predominant type of bacteria, but it can create problems in excess; the Human Microbiome Project confirmed that people who do not have much diversity in their gut flora are more likely to be diagnosed with inflammatory bowel disease (Clapp et al., 130).

So, how does any of this relate to mental health? Although people benefit from having diverse bacteria, the human body is also very sensitive to changes. If one’s diet changes suddenly, they begin taking antibiotics or probiotics, or they experience heightened stress, their gut flora will undergo changes. This can lead to an increased permeability in the intestinal wall, and material including bacteria will begin to leak through the intestine. This leakage negatively impacts your immune system and has been associated with depression and anxiety.

As mentioned in What is Mental Health Month, inflammation occurs in response to infection. If the intestine is leaking, infection and inflammation are bound to occur, and inflammation places a great deal of stress on the digestive system. Additionally, IBD caused by a lack of flora diversity can create stress. The increase in inflammatory hormones affects the blood-brain barrier, or the system that carries blood to the brain and spinal cord, which affects brain function and can lead to anxiety, depression, or memory loss (Clapp et al., 135). This is because the majority of the serotonin in the body is produced in the gastrointestinal tract, and serotonin regulates your emotional state (Harvard Health Blog). Most mood disorders like depression are inflicted by a lack of serotonin, which then has to be regulated by medication that allows serotonin to build up in the nervous system. This proves that diet can have an impact on our mental health.

This is a lot of information to take in, so how can this information be used in our daily lives?

The Solution

Since sudden changes in diet as well as a lack in variety in your diet can both negatively impact your digestive system, the best course of action is to eat a healthy and diverse diet. Processed foods that contain a lot of sugar or dairy can negatively impact your gut flora, so consider healthy alternatives such as unprocessed grains and foods with moderate amounts of dairy. Although the body may react negatively when you first begin taking probiotics, taking them can be extremely beneficial for gut flora, and some unprocessed foods also act as “natural probiotics” (Harvard Health Blog). Additionally, avoiding high amounts of sugar can help those who suffer from anxiety, because they are less likely to experience harmful sugar rushes that can exacerbate anxiety. Along the same vein, even healthy people are encouraged to avoid drinking large amounts of soda or using nicotine, alcohol, or other unhealthy substances. You should also consider foods that contain a hearty amount of vitamins or antioxidants, such as blueberries, strawberries, pecans, or broccoli.

Not everyone has access to, can afford, or can safely consume the same kinds of foods, and following a certain diet may not necessarily cure mental illness. However, changing your diet can be one of the many steps taken towards improving your overall health and your prosperity.


Clapp, Megan, Nadia Aurora, Lindsey Herrera, Manisha Bhatia, Emily Wilen, and Sarah Wakefield. “Gut microbiota’s effect on mental health: The gut-brain axis.” Clinics and Practice, vol. 7, issue 987, 2017, pp. 131-136.

Naidoo, Uma. “Eating Well to Help Manage Anxiety: Your Questions Answered.” Harvard Health Blog, Harvard Medical School, 14 Mar. 2018, www.health.harvard.edu/blog/eating-well-to-help-manage-anxiety-your-questions-answered-2018031413460.

Selhub, Eva M. “Nutritional Psychiatry: Your Brain on Food.” Harvard Health Blog, Harvard Medical School, 18 Nov. 2015, www.health.harvard.edu/blog/nutritional-psychiatry-your-brain-on-food-201511168626.

Subscribe to get sent a digest of new articles by Nadia Bey

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.