The Gut-Brain Axis
Our body has many ways to communicate. Whether it is our brain telling our feet to take steps or our stomach telling our brain it is time to eat. One thing people may not realize is that our gut can act like a second brain, communicating to and affecting our actual brain. Studies are beginning to show that the communication between the brain and gut, known as the gut-brain axis, and the specific bacteria found in the gut are connected to mental health disorders such as anxiety and depression.1 Some of the ways our gut health may be connected to our mental health has to do with the impact stress has on our bodies. The gut plays a large role in inflammation and producing hormones that are known to affect our mood such as serotonin and dopamine.2 The bacteria, or microbiota, found within our intestines help digest our food and support many other functions of daily life.
While human research on the relationship between gut health and mental health is limited, some studies are showing that those with depression and anxiety have different types and amounts of bacteria found within their gut. But why? When our gut undergoes inflammation, or stress, the microbiome in our gut releases certain chemical messengers that travel through our bloodstream to our brain. These chemical messengers can affect how the brain functions and one potential outcome is feeling symptoms of anxiety or depression.2
How Food Affects Gut Health
Researchers are starting to study how the food we eat could affect the gut-brain axis. We know that the food we eat can influence the bacteria in the gut. When we eat a diet full of different foods, we are providing the bacteria in our intestines with fuel. There are certain types of fermented foods that are known to be beneficial to gut health because they contain probiotics and prebiotics. Probiotics contain microorganisms that help maintain the good bacteria in our guts while prebiotics act as a fuel for the bacteria in our intestines.3
There are certain foods that contain probiotics and prebiotics. Probiotics are thought to be beneficial in maintaining a healthy gut microbiome since they contain live bacteria that are thought to be "good bacteria." Prebiotics on the other hand help encourage the growth of the "good bacteria" that is already found within our gut. Having a healthy and diverse gut mictobiome can help us better digest our foods, create the essential vitamins we need, and fight off bad bacteria.4
Probiotics are found in foods such as:4
- yogurt
- sauerkraut
- kombacha
- kimchi
Prebiotics are found in foods such as:4
- whole grains
- bananas
- onions
- garlic
When those with chronic stress were given probiotics for multiple weeks, they saw a decrease in anxiety and depressive symptoms.5 If the gut microbiome has the "good" bacteria it needs and is getting fuel from our diet, our body is able to work normally, and the brain and gut communicate in a more balanced manner. This may be why we see a decrease in anxiety and depression symptoms in the presence of probiotics.1
While we are seeing research that shows there is a relationship between mental health and gut health, it is still in the early stages. The food we eat can affect the bacteria in our gut but the exact role this might have on mental health is still not fully understood. Eating a diet full of a variety of foods can be beneficial in many aspects of our health, which gives our body, and gut, the nutrients it needs to properly function. It is important to discuss symptoms of anxiety and depression with a medical provider, as it is still unknown if diet can have a clear impact on mental health symptoms.
References
- Clapp M, Aurora N, Herrera L, Bhatia M, Wilen E, Wakefield S. Gut microbiota's effect on mental health: The gut-brain axis. Clin Pract. 2017;7(4):987. Published 2017 Sep 15. doi:10.4081/cp.2017.987
- Galland L. The gut microbiome and the brain. J Med Food. 2014;17(12):1261-1272. doi:10.1089/jmf.2014.7000
- Aslam H, Green J, Jacka FN, et al. Fermented foods, the gut and mental health: a mechanistic overview with implications for depression and anxiety. Nutr Neurosci. 2020;23(9):659-671. doi:10.1080/1028415X.2018.1544332
- Butler MI, Mörkl S, Sandhu KV, Cryan JF, Dinan TG. The Gut Microbiome and Mental Health: What Should We Tell Our Patients?: Le microbiote Intestinal et la Santé Mentale : que Devrions-Nous dire à nos Patients?. Can J Psychiatry. 2019;64(11):747-760. doi:10.1177/0706743719874168
- Kim CS, Cha L, Sim M, et al. Probiotic Supplementation Improves Cognitive Function and Mood with Changes in Gut Microbiota in Community-Dwelling Older Adults: A Randomized, Double-Blind, Placebo-Controlled, Multicenter Trial. J Gerontol A Biol Sci Med Sci. 2021;76(1):32-40. doi:10.1093/gerona/glaa090
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