Have you ever felt so anxious that you felt it in your stomach? If you’ve ever felt like your “gut feeling” is a reflection of your emotions, that’s because it just may be. Looking within ourselves, to the “other brain”, or our gut, can help us understand our emotions, and serve as a means to improve not only our general health, but also our mental health. Our emotions and wellbeing, lay, in part, in our gut, which can be explained by two major factors: our microbiome and a phenomenon known as the gut-brain axis.
Let’s break down the microbiome
The microbiome refers to the entire microorganism habitat of the human body, including bacteria, viruses, archaea, and eukaryotes. While these microbes exist all over our body (including skin, oral, and vaginal sites), there are 10x the number of microbes in the gut than anywhere else in the body. This makes the gut the most popular and diverse site of them all! To put this into context, there are an estimated 100 trillion microbes, and about 5,000 different species in the gut. These microbes are essential to regular gut function including digestion, metabolism, programming the immune system, and maintaining the gut wall. Microbes also produce many neurochemicals that the brain uses to regulate basic physiological processes. For example, serotonin, a neurotransmitter that is fundamental to mood and overall well being, is 95 percent made in the gut.
What influences our microbiome?
Everyone’s gut microbiome looks different from the next, but begins the same way. We get our first microbes at birth, and from then onwards, the diversity and quantity of our microbes differ based on genetic influences, environmental factors, lifestyle habits, dietary choices, and medication use. The more diverse the diet, the more diverse the microbiome. A diverse microbiome creates a happy gut. Evidence suggests that the state and fluctuations of the microbiome profoundly influence the gut-brain axis.
So what is the gut-brain axis?
The gut-brain axis is a term for the communication that occurs between the central nervous system (CNS) and the enteric nervous system (ENS). The connection between the gut and the brain appears to be bidirectional, meaning that signaling occurs from the gut to the brain and vice versa. In other words, the effects of the bacteria on the gastrointestinal (GI) tract send signals to the central nervous system, linking the gut to the brain. The immune-endocrine mediators of the gut-brain axis (GBA), as well as the cells of the GI tract, allow the brain to influence function of the gut, too. Studies suggest that anxiety and depression have links to functional GI disturbances, while irritable bowel syndrome and irritable bowel disease have links to a psychological component. Going back to the idea of “feeling sick to your stomach”- this is also the gut-brain axis at work.
A 2015 study that assessed the association between social anxiety and fermented food consumption in young adults found that those with higher genetic risk for social anxiety disorder exhibited fewer social anxiety symptoms when they consumed more fermented foods. Since fermented foods are good for gut health, this further highlights the idea of the gut-brain connection. Further, a 2011 study looked at the difference in anxiety levels between mice that were fed a broth with the microbe Lactobacillus rhamnosus compared to a control group of mice that were fed a regular broth. It was found that the mice that consumed the microbe-infused broth had an increase in the number of receptors for gamma-aminobutyric acid (GABA), an inhibitory neurotransmitter in the brain that can improve mood and decrease anxiety. This highlights another example of the potential that good bacteria have to elicit positive mood responses.
Get the good stuff
With all this talk about the gut-brain connection, there are ways to improve your gut diversity with foods such as plant-based yogurt, kefir, kombucha, sauerkraut, and kimchi. Further, a diet consisting of whole foods such as fruits, vegetables, and whole grains can lead to a more diverse microbiome as well. The diverse foods that you eat provide nutrients that help the growth of different types of good bacteria. Whether these foods have a tangible effect on one’s psychological state is still being studied, but I have a gut feeling that it does.
Hi! My name is Lina Abuhamdieh and I am a student at Georgia State University in the Coordinated Program for Dietetics. I have loved every minute of this program, and have especially enjoyed discovering new avenues in which I can work in once I graduate. My hope is to be a private practice dietitian and be able to provide clients with all things nutrition and fitness! I have also found a new passion in writing nutrition blogs, so I hope you enjoy!