While it has long been known that gastrointestinal disorders and brain disorders are linked in some way, it is only in recent years that scientists have seriously considered a direct causal link between the gut and the brain. We have long known that people with irritable bowel syndrome (IBS) are often depressed, people on the autism spectrum often suffer from digestive issues, and Parkinson’s patients may have constipation, but serious investigations into the gut-brain connection did not begin until after a 2004 Japanese study drew a causative link between the gut microbiomes of mice and their responses to stress. [This article, “Optimize Your brain Health By Improving Your Gut Health” was originally published in Newshealthwatch.]
In later years, this study gained fame as the beginning of a new field of research. New evidence now connects gut health to mood, behavior, and cognition. A wave of investigations into the gut-brain connection draws some surprising conclusions about how intimately your gut is connected to your mental health. It is now clearer than ever before that gut health promotes brain health, and just a few healthy habits can help boost your mood, clear your mind, and help you feel calm. Keep reading to learn some basic guidelines for good gut health.
The Gut Microbiome: A universe in miniature
Scientists estimate that there are about 30 trillion human cells in the body and 40 trillion bacteria. Other microbes such as yeast and fungi coexist with your gut bacteria, and altogether these make up the gut microbiome. The gut microbiome is found primarily in a pocket of the large intestine called the cecum, and it contains up to 1,000 different species of bacteria that collectively weigh 2-5 pounds.
The gut microbiome begins to take shape in the womb, with a critical period of gastrointestinal (GI) development occurring immediately after birth. Breastfed infants have higher levels of good bacteria and certain immune cells, as helpful prebiotics are transferred through human breast milk. The causative relationship between diet and composition of gut microbiota persists throughout life.
Gut bacteria perform a wide range of functions. They extract vitamins from the food that you eat, regulate digestion and metabolism, program the immune system, maintain the gut wall that protects the body from invaders, block harmful microbes, and produce chemicals that defend the body against pathogens. The balance of microbes in your gut can influence your immune system, the ability of the body to regulate homeostasis, the aging process, and according to recent research, your mental health.
Dysbiosis: A disruption in your gut
Antibiotics, stress, and changes in diet can all change the human microbiome, leading to a dysregulated state called dysbiosis. Gut dysbiosis is essentially an imbalance between the good bacteria and bad bacteria in your gut. Harmful microbes may cause inflammation and weight gain, or they may produce gas and other chemicals responsible for the symptoms of bowel disorders like irritable bowel syndrome (IBS).
In some cases, dysbiosis changes the permeability of the intestinal membrane, allowing bacteria, their products, and other molecules to leak into the blood. This condition is known as leaky gut syndrome. The toxins that enter your bloodstream from a leaky gut trigger an inflammatory response in the body. Increased intestinal permeability has been shown to cause disruptions in the immune system like those seen in a range of disorders, including inflammatory bowel disease (IBD), asthma, diabetes, and psychiatric disorders like depression and autism. More immediate symptoms of leaky gut syndrome include digestive issues, brain fog, fatigue, headaches, and skin changes.
How your mental health and mood can affect your gut
You may be aware of the gut-brain connection when you are exposed to an acute stressor, and notice your own ‘fight-or-flight’ response. As part of this response, your brain signals your GI system to slow down or stop digestion, allowing you to divert more energy towards handling the perceived threat. For example, simple anxiety such as fear of public speaking has been known to trigger a response from your gut in the form of stomach upset, diarrhea, or abdominal pain. Another example of the gut-brain connection is when gut microbes release appetite-suppressing proteins after you begin eating, telling your brain that you are about to feel full. We know that stress and anxiety can cause changes in our guts. Studies have shown that stress can suppress good bacteria in the gut, as stool samples of university students showed fewer lactobacilli during exam weeks than during the rest of the semester. Functional GI symptoms are often associated with anxiety disorders. Psychotherapies such as relaxation therapy and cognitive-behavioral therapy have been used to alleviate GI symptoms with some success. Patients undergoing these therapies were sometimes able to reduce medications and had fewer physician visits and medical procedures.
How a gut imbalance can seriously impact your mental health
You may be less aware of the gut-brain connection as it relates to how imbalances in your gut can affect your mood and cognition. Over 100 million nerve cells line the gastrointestinal tract between the esophagus and the rectum, collectively referred to as the enteric nervous system (ENS). This system is composed of the same neurons and neurotransmitters found in the central nervous system (CNS), which is why it is often called the “second brain.”
While the main role of the ENS is in controlling the functions of digestion, from release of enzymes to elimination, it also participates in a two-way communication with the brain. This connection is called the gut-brain axis (GBA). Gut bacteria respond to and produce chemicals such as serotonin, GABA, melatonin, norepinephrine, and dopamine, the same substances utilized in the brain to regulate mood and cognition. The ENS also communicates with the central nervous system (CNS) through hormones and immune cells. With rapidly evolving research into the depth of the gut-brain connection, researchers who once believed that functional bowel problems were caused by anxiety and depression are now investigating whether it may be the other way around.
It is also likely that disturbances in the GI system can send signals directly to the CNS, triggering mood changes. Recent research has linked psychiatric disorders to alterations in the gut microbiota, and scientists are exploring this gut-brain connection to develop new treatments for conditions such as anxiety and depression. For example, scientists now estimate that at least 90% of serotonin in produced in the gut, and imbalances in the gut microbiome may tip the balance of this neurotransmitter, contributing to the development of depression. Furthermore, inflammatory cytokines produced in the gut during infections may alter brain chemistry, making patients more vulnerable to psychiatric disorders. This may explain why more than 50% of patients with GI disorders such as Crohn’s disease, irritable bowel syndrome (IBS), and ulcerative colitis also suffer from anxiety and depression.
Candida: More prevalent than you might think
Candida is a yeast that causes an infection called candidiasis when it grows out of control. This usually harmless fungus lives on skin and inside the body, in the gut, mouth, and vagina, and is the most common fungal infection in humans. Under normal conditions, your healthy bacteria keep Candida under control, but if your microbiome or immune system are compromised, you may develop candidiasis. Common causes of this condition include antibiotics, high sugar intake, excessive alcohol consumption, high stress levels, and diabetes. Candidiasis may have a deleterious effect on overall health, and it has been associated with diseases such as chronic fatigue syndrome, ulcerative colitis, and Crohn’s disease. In some studies, Candida has been identified as a potential contributor to the development of autism spectrum disorder (ASD). In addition, a 2016 study found a higher incidence of candidiasis in men with schizophrenia and bipolar disorder, prompting investigations into the connection between overgrowth of this common fungus and mental illness.
Gut health especially affects behavior in children
Recent investigations have shown that the gut microbiome can influence not only neural development and brain chemistry, but a wide range of behaviors such as emotional behavior, stress response, and even pain perception. Recent research has revealed important connections between gut health and behavior in children. Studies have linked the composition of the gut microbiome to infant and toddler behavior, with measures of extroversion, cognitive development, and fear. One study of children aged 18-27 months showed connections between bacterial species in the gut and behavioral traits such as impulsivity, curiosity, and sociability. In addition, there has been evidence of significant differences in the gut microbiota in children with autism spectrum disorder (ASD) compared to children without the disorder, leading researchers to consider whether treating gut dysbiosis may alleviate behavior symptoms. Good bacteria in the gut and a healthy gut-brain connection are essential for healthy development.
Best foods to promote gut health
While certain lifestyle factors play a large role in maintaining a healthy gut, the food you consume has a major impact on the robustness of your gut microbiome. To encourage the proliferation of good bacteria in your gut, eat a fiber-rich diet including probiotic foods such as yogurt, kombucha, and sauerkraut. Probiotics can also be found in kefir, kimchi, miso, pickles, and tempeh. Prebiotics are soluble fibers that promote probiotic bacterial growth, such as the oligosaccharides found naturally in human breast milk. They can be found in high-fiber foods like bananas, whole grains, greens, soybeans, onions, garlic, and artichokes. Foods rich in polyphenols like chocolate, red wine, and olive oil also stimulate the growth of helpful bacteria. To keep your gut healthy, you should also avoid foods that harm the microbiome such as artificial sweeteners, processed and refined sugars, and trans fats.
There are a few other things you can do to protect your gut. Try only to take antibiotics when absolutely necessary, as these medications kill good bacteria in the microbiome, possibly leading to weight gain, antibiotic resistance, and other symptoms. Vitamin D and the amino acid, L-glutamine may help to repair a damaged gut lining. You can also improve gut health by quitting smoking, getting enough sleep, limiting sugar intake, and managing stress.
Probiotics can also help: What they are and what they do
The term, ‘probiotic’, is derived from the Latin for ‘promote’ (pro), and ‘life’ (biotic). The most common probiotics are Lactobacillus and Bifidobacteria. In the form of enhanced food or supplements, probiotics contain living microorganisms that change the balance of bacteria in the body. These are the ‘good bacteria’ that compete with ‘bad bacteria’ in the gut to regulate digestion and immune function. Probiotics can help to restore health by helping to repair the GI barrier, producing antimicrobial agents, supporting immunity, and adjusting the gut microbiota. These supplements have few mild side effects, the most common being gas. In addition, probiotics can help to prevent or treat diarrhea, improve symptoms of irritable bowel syndrome (IBS), reduce inflammation and allergies, and boost the immune system.
There is even a term for probiotics that positively affect mental health: psychobiotics. One study of patients taking Lactobacillus and Bifidobacteria strains over eight weeks showed a reduction in symptoms of depression as well as lowered inflammation levels. Animal studies have shown that probiotics may increase levels of tryptophan (a serotonin precursor) and GABA. (Serotonin and GABA are prominent neurotransmitters with effects on mood.) The anti-depressive effect of probiotics may also be linked to their suppression of inflammatory cytokines in the body. As researchers delve deeper into the profound connection between gut health and brain health, the underlying mechanisms are still being investigated.
Hello.Health is a notable United States-based supplement brand at the forefront of the gut-brain movement. CEO Pamela Wirth founded Hello.Health after her profound journey to alleviate her son’s physical and mental symptoms. As she consulted with specialists, Wirth discovered that restoring her son’s gut microbiome was a significant factor in his recovery. Hello.Health sells a range of pediatric supplements based on cutting-edge science, including Belly Great, a helpful blend of prebiotics, probiotics, vitamin D3, and methylfolate.
Guidelines for a healthier gut
In summary, here are some helpful tips to improve your gut health:
Consume a fiber-rich diet including probiotic foods such as yogurt, kombucha, and sauerkraut
Consume foods rich in polyphenols such as chocolate, red wine, and olive oil
Avoid artificial sweeteners, refined sugars, and trans fats
Take antibiotics only when medically necessary
Manage stress and be sure to get enough sleep
Quit smoking and drink only in moderation
Consider prebiotic and probiotic supplements
A healthier gut for a healthier psyche
As an emerging field, the study of the gut-brain connection has produced some startling discoveries about how profoundly gut health affects brain health. Researchers studying neuro-diseases such as depression, Parkinson’s disease, Alzheimer’s disease, autism, and multiple sclerosis have begun to pay more attention to gut health, as scientists learn more about the intricacies of our “second brain” and its connection to the central nervous system. While lifestyle factors such as quitting smoking, drinking only in moderation, and getting enough rest can help maintain a healthy gut, probiotic and prebiotic supplements are also a smart choice. As science delves deeper in to the ties between childhood behavior and the composition of the gut microbiome, supplement makers like Hello.Health are beginning to offer healthy pediatric options. Adults can also benefit from a wide selection of probiotic and prebiotic supplements available in stores and online. The movement of modern medicine towards more holistic approaches to health only supports deeper investigation into the mind-body connection. With each passing year, there is greater reason to maintain your gut health. In doing so, you may feel happier, sharper, and perhaps even wiser.
Further reading:
NIH: 4 Fast Facts about the Gut-Brain Connection
PSYCOM: The Gut Brain Connection: How Gut Health Affects Mental Health
Science: Your gut is directly connected to your brain, by a newly discovered neuron circuit
Disclaimer
Important Note: The information contained in this article is for general informational purposes only, and should not be construed as health or medical advice, nor is it intended to diagnose, prevent, treat, or cure any disease or health condition. Before embarking on any diet or program of nutritional supplementation, it is advisable to consult your healthcare professional in order to determine its safety and probable efficacy in terms of your individual state of health.
