“I’ve got this gut feeling”, we often say to describe the connection between our digestive system and our brain. Science is catching up with what we’ve been describing all these years. The digestive system has its very own brain called the enteric nervous system. Many people will experience the effects of stress in the digestive system due to the connection between the gut and the brain. The bacteria that live in the digestive system are responsible for the production of many of our neurotransmitters (brain chemicals). Simple lifestyle changes can improve your digestive health and subsequently your mental health. Understanding the relationship between the gut and the brain can help you lead a healthier and happier life.
The vagus nerve is the main parasympathetic nerve that influences many of our functions including digestion. The parasympathetic nervous system is our “rest and digest” state. Many of us live in the sympathetic nervous system state also referred to as “fight or flight”. When you’re functioning in “fight or flight” mode, you cannot optimally activate your digestive processes. Taking time to sit down to eat and focusing on your meal can improve your ability to digest and absorb the benefits of your food. Eating in a rush, at your desk or while on-the-go doesn’t allow your body to get into a parasympathetic state. Mindfulness practices around mealtime can also help you to activate the parasympathetic nervous system. Deep belly breathing and/or meditation can get your body into a “rest and digest” state.
Stress keeps us in the “fight or flight” state of our nervous system and prevents us from accessing “rest and digest” functions. Stress hormones including cortisol and noradrenaline can impact the bacteria that live in our guts (our micro biome). The bacteria in the digestive tract are responsible for many functions. Overgrowth of unhelpful bacteria can cause digestive distress including heartburn, diarrhea, bloating and other uncomfortable symptoms. Certain bacteria can damage the intestinal epithelium (lining of the digestive tract) and as a result of the damage, inflammation occurs. Cytokines are chemicals that talk to the immune system throughout our body. When these chemicals are released in the gut, they can impact other parts of the body including the nervous system. Beneficial gut bacteria help to maintain digestive and immune health throughout the body.
The beneficial bacteria that live in our gut are also responsible for the creation of neurotransmitters including serotonin and GABA. Serotonin is our happy and calm neurotransmitter. Many drugs that treat depression work on keeping serotonin around in the brain to provide more of its pleasant, mood-boosting effects. GABA is short for gamma aminobutyric acid, an inhibitory neurotransmitter involved in calming the brain and decreasing nervous system activity. Serotonin and GABA are both important neurotransmitters that impact depression and anxiety. The bacteria in our gut also impact digestive function. Certain strains of bacteria can protect against illnesses like travelers’ diarrhea and can be used in combination with medications to treat severe bowel infections like C. difficile. Taking care of the bacteria that make up your micro biome can contribute to optimal mental and digestive health.
To maintain a healthy bacterial balance, it’s important to fuel the bacteria with foods they like. Fibrous foods help to maintain a healthy micro biome by acting as a prebiotic. Consuming vegetables, fruits and whole grains provides a good amount of fibre. Fibre and prebiotic supplements are available, but many people react to prebiotic isolates with gas and bloating. Check with your health care provider to find out what is right for you. There is limited evidence regarding the consumption of fermented foods to benefit colonizing bacteria. Things like kimchi, kombucha and sauerkraut may provide some beneficial bugs but because the types of bacteria and volume can vary in these foods, the data to show their effect remains mixed. Probiotic supplements can be used for both gut health and mental health. Specific strains are chosen for unique individuals. Check with your healthcare provider for what type of probiotic supplement may be best for you.
The connection between the gut and the brain is a two-way street. Stress impacts the digestive system through blocking the impact of the vagus nerve and preventing us from entering a “rest and digest” state. Stress also alters the bacteria that live in the digestive tract. These bacteria are responsible for many functions including the production of neurotransmitters like serotonin and GABA. Maintaining gut bacteria through consuming a variety of vegetables and fruits can help foster healthy digestive function. If you suspect your digestive system is impacting your mental health, or stress is impacting your digestive system, visit your healthcare provider to investigate ways to improve the balance between the gut and the brain.
By Dr. Briana Botsford