How Your Gut affects Your Mental Health
Have you ever experienced “butterflies” in your stomach before a big event or stressful situation? Do you get stomach issues when you’re stressed out? If so, these are examples of how your brain can affect your gut health. However, your gut can also affect your mental health. Ever get in a bad mood when you’re constipated or get brain fog after a large meal? Your gut and brain are intricately connected through what has been termed the “gut-brain axis”. This means that your mental health has an influence on your gut health and vice versa. If you’re struggling with issues such as anxiety, depression, or brain fog, the answer could be in your digestive system.
How do the brain and gut communicate with each other? There are a few different mechanisms of how this takes place. The first is through the vagus nerve, which is the 10th cranial nerve. Vagus is Latin for “wandering” or “straying”, which is why the vagus nerve is sometimes referred to as the “wandering nerve”. Branches of the vagus nerve go to many different organs of the body including the heart, lungs, liver, kidneys, stomach, and intestines. It is a direct link between your gut and brain. The gut can send information to your brain via this nerve, and the brain sends autonomic signals to the gut to maintain proper motility and peristalsis (the movement of food through your digestive tract).
The gut can also communicate with the brain through the enteric nervous system, which is often referred to as the “second brain” or the “brain in your gut”. The enteric nervous system is a large network of neurons (estimated to be between 200 and 600 million) in the digestive system that operates independently of the central nervous system and controls digestion. However, it communicates with the central nervous system through the sympathetic (fight-or-flight) and parasympathetic (rest and digest) branches of the autonomic nervous system. This communication pathway explains why mental stress affects the gut and vice versa.
Another way the digestive system can affect the brain is via the gut microbiome. The microbiome consists of trillions of microbes which can have a major impact on mood, emotions, and overall mental health. These microbes produce neurotransmitters, hormones, and other metabolites that affect brain and nervous system health. In fact, 90-95% of serotonin, a “feel-good” neurotransmitter that can affect mood, is produced in the gut. Other neurotransmitters such as dopamine and GABA are also produced by gut bacteria. Research has shown that dysbiosis and inflammation in the gut are linked to several mental health issues including anxiety and depression.
When dysbiosis and increased intestinal permeability (“leaky gut”) are present, it leads to inflammation in the gut that can then affect the brain. Increased production of inflammatory cytokines, decreased production of neurotransmitters, and decreased vagus nerve tone are potential results from poor gut health that will have a negative impact on brain and nervous system function. However, as mentioned before, the effect can go both ways. Poor mental health can also impact the gut through similar mechanisms. Chronic mental and emotional stress leads to increased levels of cortisol and other stress hormones, affecting motility in the gut, lowering stomach acid levels, and affecting overall digestion. This occurs through an overactive sympathetic nervous system response and decreased vagus nerve function.
The vagus nerve in particular plays a key role in digestion and gastric motility. It helps regulate stomach acid levels, digestive enzyme production, lower esophageal sphincter function, and overall motility and peristalsis in the gut. If vagal tone is decreased, it can cause decreased gut motility and stomach acid levels, which can result in conditions such as acid reflux and SIBO (small intestinal bacterial overgrowth).
What are some signs that your gut-brain axis may be out of balance? Mental health symptoms often occur in conjunction with digestive issues, but the severity of each may differ. Here are some signs to look out for:
Digestive issues such as abdominal discomfort, bloating, constipation, and diarrhea
Mood changes and mental health issues such as anxiety, depression, irritability
Brain fog, lack of concentration, memory issues, and fatigue
Increased food sensitivities or cravings
How can we support a healthy gut-brain axis? Managing stress is one important factor as chronic stress will have a negative effect on the brain and gut. Things like prayer, deep breathing, meditation, time in nature, and exercise can help manage stress levels. Proper sleep is also important for both brain and gut health, so good sleep hygiene will also be helpful. Going to bed and waking at a similar time each day, avoiding screens before bed (or wearing blue blocking glasses), keeping the temperature cool at night, and avoiding alcohol and large meals before bed are examples of good sleep hygiene techniques.
Taking care of the gut and digestive system is also very important, but this can be unique and personalized to each case. For example, eating a fiber-rich diet and fermented foods such as kimchi and kefir may be great for many people’s gut health, but maybe not if you have a condition such as SIBO or histamine intolerance. Working with a knowledgeable functional medicine practitioner can help you determine what works best for your individual situation. If your symptoms are persistent or severe, advanced testing may be needed to look for deeper imbalances and dysregulation.
The gut and brain are constantly communicating, and if there is an imbalance in one it will affect the other. If you are struggling with mood or digestive issues and are looking to get back on track, we can help! Schedule a free discovery call today to see how we can assist you in reaching your health goals.