Food for Thought: Mental Health and the Gut

Welcome to The Perfect Stool. This is your host, Lindsey Parsons, and today I'm going to be talking about the gut-brain axis. What is the relationship between the brain and the gut? What do our thoughts and emotions have to do with our microbiome and digestive health? What does our digestive health have to do with our mental health? Can we improve our mental health by improving our gut health? On this episode, I'll be exploring these questions and the complicated connection between the brain and the gut. So if you're a gut health geek like myself, I'm sure you've already heard a lot about the gut-brain axis and probably have some idea that the health of your gut has some relationship to the health of your brain. But the extent to which this is true is perhaps more than you realize. And it's not just that a dysbiotic, leaky, or unhealthy gut can lead to brain fog, depression, or anxiety, but also that dysfunctions in the brain can lead to a leaky gut and a leaky brain. In the Western medicine model, doctors traditionally viewed the body and its systems as linear, as in a symptom or dysfunction in one organ can be traced to another, period. Which leads to solutions that address just one organ or mask the symptoms. But in Chinese medicine and Ayurvedic traditions, bodily systems are cyclical. So rather than this causes that, a cyclical model of the body suggests that there may be multiple root causes which impact one another, and the health of a given organ can be influenced by another organ, which then influences the original organ. And the gut-brain axis is a perfect example of this kind of cyclicality. So one example of gut-brain dysfunction can begin with decreased brain activity. So this could come from, say, a brain injury, a concussion, or stress. For example. And that decreased activity can lead to a decrease in the activation of the vagus nerve, which is the main component of the parasympathetic nervous system, which is one arm of the enteric nervous system, or the two thin layers of more than 100 million nerve cells that line the gastrointestinal tract from the esophagus to the rectum. And then the other branch being the sympathetic nervous system, which controls our fight or flight response to a stressor. So the parasympathetic nervous system oversees many crucial bodily functions like digestion, control of mood, immune response, and heart rate, specifically undoing the work of the sympathetic nervous system after a stressful situation and bringing your body into the rest and digest mode by decreasing respiration and heart rate and increasing digestion when you're resting, relaxing, or eating. So back to the vagus nerve. The vagus nerve connects the brain and the gastrointestinal tract and sends information about the state of the inner organs to the brain via fibers. And decreased activation of the vagus nerve then will suppress the intestinal immune system and decrease intestinal blood flow. Which slows digestion and can cause increased growth in pathogenic yeast and bacteria, which then causes intestinal permeability or leaky gut. Leaky gut causes a state of chronic low-grade inflammation, and then you have inflammatory cytokines or chemical messengers that are produced in the gut, and they travel through the blood and cross the blood-brain barrier, which activates the microglial cells, which are the immune cells of the brain, and then the brain gets inflamed. That inflammation creates a leaky blood-brain barrier, also known as leaky brain, And then, you know, if you think of the blood-brain barrier, it's a single-layered lattice of cells joined by tight junction, which regulates which substances are allowed into the brain, not dissimilar to the way the intestinal epithelial cells regulate what's let in and out of the intestines. And generally, the blood-brain barrier keeps out toxins like heavy metals, pesticides, and damaging proteins while allowing in oxygen, hormones, and nutrients. But when it gets leaky, of course, then you have things entering the brain that don't belong there. So the brain inflammation also then decreases nerve conductance, which then can cause depression and reduce activity at the vagus nerve, which controls mood. And we're back where we began, caught in a vicious cycle in which reduced activity in the brain causes gut inflammation, which inflames the brain, which leads to reduced brain activity. And you see the cyclical nature of it. It's important to recognize that when gut symptoms persist, even in the context of a healthy diet and lifestyle, this could be an indication of a gut-brain axis problem. And if you suspect that your symptoms may have their origin in the brain, you should definitely listen to my podcast episode 20 with Corey Deacon, who delves into the electrical dysfunctions from the brain that can lead to gut issues and how he uses electrogastrograms and neurofeedback to correct them. Likewise, your problem can originate in the gut with a poor diet lacking in fiber and high in gluten and dairy and other typical food allergens, which creates intestinal permeability and can set off the same series of events terminating in mental health issues. That was a mouthful. So now let's get a little bit into the research evidence of the relationship between depression and the gut microbiota. So in a study published in the journal Nature Microbiology in 2019— and there'll be links to all of these studies in the show notes— researchers in Belgium sequenced the microbiome of 1,054 individuals, and they correlated their findings with measurements of both quality of life indicators and depression status of the participants. And they found that those with lower levels of Bacteroides enterotype 2 displayed lower measurements of quality of life and a higher prevalence of depression, while those with higher quality of life indicators were consistently correlated with higher levels of Faecalibacterium and Coprococcus, which produce the short-chain fatty acid butyrate, which feeds gut epithelial cells and helps maintain a healthy gut barrier. Now, if you wanna understand a bit more about the role of butyrate, you should check out my episode 25 with Lucy Malin that goes into a lot more detail on that. They also found the lack of Dialister and Coprococcus species also correlated with higher levels of depression, and the researchers then looked at the genetics of the particular organisms and their role in manufacturing neurotransmitters like dopamine and GABA, which led to the suspicion that this may be another role that the microbiome is playing in mental illness because of the neurotransmitters that those microorganisms produce. So overall, while we can't say these particular organisms cause depression or the lack of these ones cause it, what we do know for sure is that a healthy gut microbiome will decrease inflammation and the inverse, an unhealthy one increases it. Which has an impact on depression, which is at its core an inflammatory disorder. Then there's another study which was a systematic review of studies on major depressive disorder and the gut microbiome, which found that there were 9 genera over those studies that were higher in major depressive disorder: Enterostipes, Blausia, Clostridium, Klebsiella, Lactobacillus, Parabacteroides, Paraceterella, Faecalactobacterium, and Streptococcus. And then there were 6 that were lower: Bifidobacterium, Dialister, Escherichia, Shigella, Faecalibacterium, and Ruminococcus. And 6 that were divergent, meaning different results in different studies. So what they suggested, and what I've heard from other researchers, is that studying the microbial functioning, or the function that any genera of microbes may play, may be more productive than a purely taxonomic approach, or singling out specific families, genera, phyla, etc., bacteria to understanding the gut microbiome in depression. So going into a bit more detail on the role of specific gut bacteria in creating neurotransmitters, studies have shown that Lactobacillus and Bifidobacterium, which are typical genera in multistrain probiotics, synthesize GABA from monosodium glutamate, which is notable because it's hypothesized that depression may be caused by a deficit in GABA. And Escherichia coli, or E. coli— by the way, you may be familiar with it as a pathogen, but in fact E. coli, there's many healthy types of E. coli as well— bacillus and Saccharomyces produce norepinephrine, which you may also know as noradrenaline, and whose general function is to mobilize the brain and body for action. And Candida, which is a yeast of course, not a bacteria, and Streptococcus and Escherichia and Enterococcus produce serotonin, which is the key hormone that stabilizes our mood, feelings of well-being, and happiness, and helps with sleeping, eating, and digestion. And Bacillus and Serratia produce dopamine, which plays a role in how we feel pleasure. So this is leading all to research into a new class of drugs called psychomicrobiotics for the treatment of psychiatric disorders. Then another study shed some light on the mechanism by which the gut microbiome can cause depression. And it was a controlled clinical trial on patients with major depressive disorders that helped validate the existence of an immune response to LPS, or lipopolysaccharide, which is a component of the cell walls of gram-negative bacteria. And LPS is believed to play a role in depression along with inflammatory cytokines. And the study looked at concentrations of the immune cells IgM and IgA, or immunoglobulin M and immunoglobulin A, against LPS of 6 particular gram-negative bacteria from the family Enterobacteria, which would indicate that there's an immune response in the blood to those bacteria. And they found that the prevalences and the median values for serum IgM and IgA against LPS— in other words, the immune response to that LPS for the Enterobacteria— was significantly greater in patients with major depressive disorder than in normal volunteers, which led them to conclude that intestinal mucosal dysfunction characterized by an increased translocation of gram-negative bacteria also known as leaky gut, plays a role in the inflammatory pathophysiology of depression, which means that the blood-based immune response indicates that this LPS is escaping the intestines and creating this immune response. And they go on to suggest that patients with major depressive disorder should be checked for leaky gut by means of the IgM and IgA panels used in the study and be treated for it. So we've talked a bit about depression, so let's move on to anxiety, which of course has a lot of overlap with depression. And if you've ever had an experience that made you feel nauseous or you've had butterflies in your stomach before a public speaking event, I'm sure you're clued into how your gut responds to anxiety-producing situations. And conversely, conditions in your gut can trigger various emotional responses in your brain, like anxiety, which studies have shown may affect up to a third of people at some point in their life. So the enteric nervous system, which I mentioned before, doesn't just send messages to regulate the digestive system. It also receives information from the digestive system, which creates thoughts in your brain. So for a long time, researchers and clinicians thought that anxiety and depression contributed to conditions like IBS and other problems. Like constipation, diarrhea, bloating, pain, and upset stomach. And now the new research suggests that the reverse is true as well, that people suffering from IBS and other functional bowel problems are at a much higher risk of developing depression and anxiety. And as a result, you may find that your gastroenterologist may suggest antidepressants to treat your IBS, not because they think that the problem is in your head or that you're depressed, but because the medications can calm symptoms by acting on nerve cells in the gut, as can other psychotherapies like cognitive brain training. So looking at the research evidence on gut-based interventions for anxiety, there was a systematic review of 21 studies with 1,503 people in 2019 that examined the evidence from observational studies to support the improvement of anxiety symptoms by regulating the intestinal microbiota. Of the 21 studies, 14 used probiotics as the intervention to regulate the microbiota, and 7 used non-probiotic interventions like diet adjustments. And overall, 11 of the 21 studies showed a positive effect on anxiety symptoms by regulating the gut microbes. Of the 14 studies that used probiotics, more than a third found them to be helpful in reducing anxiety symptoms, while 6 of the 7 remaining studies that used other means found those to be effective. So the researchers concluded that more studies are needed to clarify the conclusion that non-probiotic interventions are more effective than probiotic interventions in reducing anxiety. But overall, they did affirm that regulating intestinal flora is effective in alleviating anxiety symptoms. Of course, you have to keep in mind as well that often studies use different probiotics in each one. So it may be that certain probiotics are more effective than others. And if you did listen to my episode 23 on Pandas, Autism, Anxiety, and Depression: One Family's Miraculous FMT Healing Story, you really should go back and find that one. It's an amazing story of how fecal transplants profoundly change the lives of 3 members of one family and their mental health. And it goes even further than just depression and anxiety, even to schizophrenia. A 2019 study in Science Advances found that patients with schizophrenia had lower microbiome diversity and marked disturbances of microbial composition versus healthy controls. In addition, there were several unique bacterial taxa, Velonellaceae and Lactosporaceae, that were associated with schizophrenia severity. They also took the stool from the subjects with schizophrenia and the healthy controls and put the stool into germ-free mice. And the mice who received the fecal transplants from the subjects with schizophrenia had lower glutamate and higher glutamine and GABA in the hippocampus and displayed schizophrenic-type behaviors. So now that I've talked about the importance of the relationship between the brain and the gut for some common mental health issues, I want to cover other ways it may look when the gut-brain axis isn't functioning well. So some signs and symptoms of gut-brain dysfunction include fatigue, brain fog, chronic digestive problems, progressive cognitive decline, memory problems, of course anxiety and depression, ADHD, autism spectrum disorder, behavioral problems, and even cold hands and feet, especially if you have toenail fungus, which is evidence of reduced blood flow to your peripheral tissues, which can include the brain. Now, since my whole show is about healing gut issues, I won't go deep into how that's done in this episode, except to say that correcting gut issues usually starts with testing to determine the nature of your problems, like whether you have an overgrowth of bacteria, particular pathogenic bacteria, parasites, or fungi, or just general dysbiosis. And then treatment with antimicrobials or antiparasitics, prescription or herbal, to eliminate the pathogenic bacteria, parasites, or fungi. Then changes in diet, often through an elimination diet and testing of different foods. Sometimes the addition of supplements like betaine HCl which is like stomach acid or digestive enzymes, and the addition of probiotics and prebiotics, either through food or sometimes through supplementation. And of course, addressing nutrient deficiencies, which is common when you have gut dysfunction. But considering the brain's role in health, it's also important to consider that regular exercise, rest, being outdoors in the sun, reading, listening to music, and implementing stress management practices like yoga and meditation are important tools not just to relieve stress, depression, and anxiety, but may be critical to alleviating your gut symptoms. So there's clearly a lot more to say about the gut-brain axis and the relationship between mental health and digestive health, and I hope to bring some researchers and experts in on this subject in the future. But I'm going to stop here for today. But in closing, I do want to recommend that if you or one of your loved ones are suffering from chronic mental health issues, that you consider the role of your gut and the gut microbiome in trying to address it. If you do need help in this area, I offer free 1-hour health restoration breakthrough sessions to hear about the struggles you've been having and hear what you've tried and tell you how gut health coaching may help you find a path to healing. And if you want to set up one of those, you can find a link in the show notes or go to High Desert Health and look under Work With Me, Health Coaching, Gut Health Coaching. And if you'd like to connect with me on social media, I'm on all the major channels under some form of High Desert Health, and links are in the show notes. And you can also join my gut healing group on Facebook. So thank you for listening, and here's wishing you all the perfect stool.