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Microbes and Mood - What You Need to Know About the Gut-Brain Connection


GUT MICROBES AND PROBIOTICS


Similar to a rainforest, the human microbiome is incredibly diverse and complex, with many species yet to be discovered. There are an estimated 10-100 trillion bacterial cells in our body, which is 10 times greater than the number of human cells. Bacteria are found all over the body, including the skin, nose, mouth, and especially, the gut. The microbes that live in our gut are known as “gut microbiota.” Some of these gut bacteria are beneficial and help us make and absorb nutrients, improve digestion, and regulate our immune system, while other bacterial species are considered harmful, or "potentially pathogenic." Fortunately, the "good" bacteria help protect us from many of the harmful microbes, which is one of the reasons why supporting our microbiome is so important.


These friendly microbes do more than help us digest foods, make vitamins, and protect us from the not-so-friendly microbes, though. They have mental health benefits too!


GUT-BRAIN CONNECTION


It may not seem obvious or intuitive, but your body is interconnected in many ways and more research is focusing on the “microbiota-gut-brain axis.” This axis is a complex bidirectional communication system connecting your gut, its microbes, and your brain.


In fact, there are several pathways linking the gut to the brain. One is via the “vagus” nerve, which is a nerve that directly connects your gut to your brain. Other pathways connecting the gut to the brain involve “biochemical messengers," which are made in your gut and travel throughout the body to communicate with other organs, including your brain. Examples of these messengers include short-chain fatty acids, cytokines, and even tryptophan (the amino acid that the neurotransmitters melatonin and serotonin are made from).

The exciting thing is that this may help us with not only mood and stress, but the microbiota-gut-brain axis may one day prove to be helpful for other conditions like autism and Parkinson’s.

MOOD, STRESS, AND YOUR MICROBES


Neurotransmitters such as serotonin, dopamine, γ-aminobutyric acid (GABA), histamine, and acetylcholine are largely synthesized, or made, in the gut by beneficial bacteria. In fact, 90% of serotonin and 75% of all neurotransmitters are made in the gut. You can see why microbiome health is an important, and sometimes overlooked, aspect of mental health.


Mood disorders are complex and can involve any number of underlying factors; however, recent research has uncovered a potential role of gut microbiota in the development and progression of various mood disorders. Additionally, some studies have shown that individuals suffering from gastrointestinal symptoms are more likely to suffer from neuropsychiatric symptoms.


Several studies show that stressed rodents not only have increased stress hormones and stressed behaviors, but they also have different gut microbes! This has also been studied, to a lesser extent, in humans. One study showed that moms with high levels of stress hormones during pregnancy had infants with more of the “bad” gut microbes. But, can it work the other way around? Can changing our gut microbes affect our moods and stress responses?


Studies of rodents that live without any gut microbes at all (in a “germ-free” environment) respond to stress more than mice with normal gut microbes. Then, when they’re given either a probiotic or gut microbes from non-stressed mice, their stress responses often go back to normal.

Many animal studies show positive effects on behavior when given probiotic supplements. For example, after a probiotic, stressed rats had lower levels of both stress hormones and an inflammatory molecule associated with depression (“LPS” - lipopolysaccharide). Human studies show that after a few weeks of taking probiotic foods or supplements, healthy people have reduced stress hormones, feelings of stress, negative thoughts, and sad moods.

One fascinating study showed that when people took certain probiotics, brain MRI (magnetic resonance imaging) tests showed reduced brain activity for negative and aggressive thoughts!

There is some exciting research on the positive effect that probiotics can have on moods and stress. So, what can you do to support your own healthy gut microbes?.


PROBIOTIC-RICH FOODS AND SUPPLEMENTS


The microbes that we can ingest are known as “probiotics.” “Probiotics” are live organisms that you can eat, drink, or take as a supplement. They turn milk into yogurt, and cabbage into sauerkraut, and they are great for both your gut health and mental health. Special probiotics that have mental health benefits are called “psychobiotics,” (psycho = mental health, and biotics = live).


Probiotics can be found in yogurt, sauerkraut (and other fermented veggies), miso, tempeh, and kimchi. You can drink them in kefir or kombucha. Of course, there are a number of probiotic supplements available too. Check with your healthcare provider to identify which one is best for you as many of the effects of probiotics are dependent on the specific strain.


SIMPLE, PROBIOTIC-RICH RECIPES


Try some of these favorites from Living Plate Rx


PREBIOTICS


PREbiotics are "the stuff that good bacteria feed on," and when fermented in the gut, produce specific changes in bacterial composition or activity. They are your friendly gut microbes’ favorite delicacies so they’ll happily grow, and multiply. Prebiotics are basically foods that contain fiber. Things like fruits, vegetables, nuts, and seeds. Even dark chocolate (preferably with at least 70% cocoa). Foods that are particularly high in prebiotics include jicama, asparagus, avocados, bananas, Jerusalem artichokes, legumes, whole grains, and allium vegetables like onions, garlic, leeks, and shallots.

Giving animals prebiotics has been shown to reduce stress hormones and anxiety-related behaviors. In human studies, taking psychobiotics along with prebiotics has been shown to improve both the composition of the gut microbiota as well as mood.


PREBIOTIC-RICH RECIPES



Sources


Huang, T. T., Lai, J. B., Du, Y. L., Xu, Y., Ruan, L. M., & Hu, S. H. (2019). Current Understanding of Gut Microbiota in Mood Disorders: An Update of Human Studies. Frontiers in genetics, 10, 98. https://doi.org/10.3389/fgene.2019.00098


Marotta, A., Sarno, E., Del Casale, A., Pane, M., Mogna, L., Amoruso, A., Felis, G. E., & Fiorio, M. (2019). Effects of Probiotics on Cognitive Reactivity, Mood, and Sleep Quality. Frontiers in psychiatry, 10, 164. https://doi.org/10.3389/fpsyt.2019.00164


Vitellio, P., Chira, A., De Angelis, M., Dumitrascu, D. L., & Portincasa, P. (2020). Probiotics in Psychosocial Stress and Anxiety. A Systematic Review. Journal of gastrointestinal and liver diseases : JGLD, 29(1), 77–83. https://doi.org/10.15403/jgld-352


Zijlmans, M. A. C., Korpela, K., Riksen-Walraven, J. M., de Vos, W. M., & de Weerth, C. (2015). Maternal prenatal stress is associated with the infant intestinal microbiota. Psychoneuroendocrinology, 53, 233–245. https://doi-org.uws.idm.oclc.org/10.1016/j.psyneuen.2015.01.006

 
 
 

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