It was once thought that the brain and body were separate entities with only a physical connection. However, recent research has highlighted the interconnectedness of the brain and body, and how the health of each one influences the other.
The brain is connected to the body (more specifically, the gut) via a long nerve called the vagus nerve. The vagus nerve is one of the 12 cranial nerves, which are paired nerves that run from your brain down to your face, neck, and torso.
The relationship between the brain and gut is known as the gut-brain axis (GBA), and it explains how your mental state influences your digestion and vice versa. The bidirectional communication between the brain and gut helps with mood regulation, appetite, and metabolism.
In this article, I want to cover the gut-brain connection in more detail. I’m going to discuss the most common gut issues that people experience, how your brain impacts your gut, and how to effectively manage your GBA.
What Are the Most Common Issues With the Gut?
Although there are thousands of gut-related issues that you can face, some are more common than others. Let’s take a look at some of the most common gut issues and their causes.
Bloating
Bloating is by far the most common digestive issue that people experience. It’s often temporary and resolves on its own but can also become a chronic issue for some.
You can become bloated by consuming lots of high-fat or high-salt foods, being dehydrated, being inactive (such as when you’re travelling or on holiday), or having gut dysbiosis. Stress can also be a key contributor to bloating. You’re also more prone to bloating if you suffer from a digestive disorder, such as irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD).
If you’re a woman, you might find that you’re more likely to get bloated in the days leading up to your period and during your monthly bleed itself. This is due to the fluctuations in oestrogen and progesterone that occur naturally during the latter phase of the menstrual cycle.
During the first trimester of pregnancy, a hormone called human chorionic gonadotropin (hCG) is high. In the second and third trimesters, this hormone is replaced by progesterone. Both hCG and progesterone can cause digestive issues, including bloating and heartburn.
Excess gas
Excess gas is caused by eating too quickly and swallowing too much air whilst you’re eating. You can also have excess gas in your digestive tract from eating lots of gassy foods like cruciferous vegetables, onions, apples, peaches, pears, beans, and wheat bran.
Excess amounts of gas in the digestive tract tend to lead to bloating and abdominal distention, neither of which are particularly enjoyable! Bloating and swelling of the abdomen are extremely common digestive symptoms, but thankfully, they are easily avoidable with mindful eating and dietary changes.
Constipation
Another common digestive issue is constipation, which may come and go for some or be a chronic issue for others. Constipation is difficult to diagnose accurately because everybody’s regularity is different. Some people have a bowel movement every day, whilst others go every other day or every few days. Each person’s normal toilet habits are unique to them.
However, medically, constipation may be diagnosed if an individual has a change in habits from frequent bowel movements to fewer than three toilet trips a week. Generally, constipation is accompanied by bloating, abdominal distension and abdominal cramps.
Diarrhoea
Diarrhoea is an issue where you have very loose stools that are watery and runny. More specifically, diarrhoea refers to the passage of three or more watery stools within a 24-hour period.
You can experience diarrhoea transiently due to consuming foods that don’t agree with your stomach (usually spicy foods are the culprit in this case) or a stomach bug (which may Aldo cause nausea, vomiting, and fever)
Some people get diarrhoea regularly due to a digestive health issue. For example, diarrhoea is a common symptom of Crohn’s disease and often requires anti-motility medications like Loperamide to manage.
Irritable Bowel Syndrome
Irritable bowel syndrome (IBS) is a common digestive disorder that causes bloating, flatulence, abdominal cramps, constipation, and diarrhoea. Most people will either experience more constipation (IBS-C) or more diarrhoea (IBD-D), although some people (unfortunately) get the best of both worlds (known as IBS-M for ‘mixed’).
IBS impacts millions of people around the world, but we still don’t fully know what causes it. There are speculations and hypotheses that suggest IBS is caused by autoimmunity, reduced gut motility, increased gut sensitivity, gut dysbiosis, certain dietary components, and stress.
How Can Your Brain Impact Your Gut?
Your brain and gut can communicate with one another, allowing for signalling between the central nervous system (the brain and spinal cord) and the enteric nervous system (the network of nerves in the gastrointestinal tract).
Here's how your brain can impact your gut via the gut-brain connection.
Emotions and feelings
Your emotions and thoughts cause specific feelings, which directly impacts your gastrointestinal function. For example, you might find that when you are particularly stressed, your digestion goes out of the window, and you experience, bloating, constipation, diarrhoea, or all three. When your stress returns to its baseline level, you might find that your symptoms disappear.
Another experience that you will likely have had relating to the GBA is the feeling of butterflies in your stomach when you are nervous or anxious. There’s also something known as the gut feeling, which was once thought to be a spiritual concept but has now been recognised as a manifestation of the gut-brain connection.
Stress response
When you experience stress, whether physical or psychological, your body responds by activating the sympathetic nervous system, causing what is known as the ‘fight or flight’ response (sometimes called the ‘fight, flight, freeze’ response).
This stress response is an ancient mechanism controlled by the most primitive parts of the brain, and it’s built into every human being. It causes a reduction in blood flow to the gastrointestinal tract, slowing down gut motility and reducing digestive enzyme secretion. In turn, this stress and anxiety can cause bloating, constipation, and poor nutrient absorption of ingested food.
Hormone regulation
The brain produces neurotransmitters that can influence gastrointestinal function, including serotonin, which regulates mood, appetite, and gut motility. Serotonin fluctuations can, therefore, impact the gut and may contribute to digestive disorders like IBS and IBD.
The gut bacteria are responsible for producing between 80 and 95% of the serotonin in the body, further strengthening the close connection between the brain and digestive tract.
Immunity
Between 70 and 80% of immune cells reside in the gut. The bacteria that form part of the gut microbiome contribute to immunity by creating a barrier that prevents pathogenic microorganisms from entering the bloodstream through the intestinal wall.
The gut contains specialised immune cells that form gut-associated lymphoid tissue (GALT). The brain can modulate the immune functions of the gut by signalling it with various neurotransmitters and hormones. If this signalling is disrupted, it can lead to gut dysbiosis, inflammation, and autoimmune issues.
Gastrointestinal sensations
The gastrointestinal tract contains sensory nerves that transmit signals to the brain, which perceives these signals as sensations. To name a few examples of these sensations, you can experience hunger, fullness, abdominal distension, or a feeling of butterflies in your stomach in response to the bidirectional communication between your gut and brain.
How Can I Manage the Gut-Brain Connection?
Although the gut-brain axis is largely involuntary and the processes I’ve mentioned above occur every day without you even realising, there are things that you can do to manage the GBA. I’ve listed some of these things below.
Take probiotics
Probiotics are found naturally in the gut, and they refer to beneficial strains of bacteria, such as Lactobacillus or Bifidobacterium. These bacterial species aid the production of vitamin K, vitamin B12, and short-chain fatty acids in the gut. They also aid immunity by keeping the levels of potentially dangerous bacteria low.
Probiotics are essential for healthy digestion and reducing the risk of digestive disorders. Even though they are found naturally in the human colon, you can support your endogenous probiotic bacteria by taking a probiotic supplement or consuming probiotic-rich foods.
It’s important to choose a trusted probiotic supplement that contains enough probiotic bacteria to be efficacious. A Dose For Bloating contains one million probiotic bacteria for maximum effectiveness. Within just a week or two of daily consumption, A Dose For Bloating can eliminate bloating, constipation, and other digestive symptoms.
You can also consume fermented foods like yoghurt, miso, tempeh, tofu, pickled vegetables (like sauerkraut), and kombucha to boost your probiotic intake.
Boost your serotonin
You can increase your levels of serotonin in a number of ways, and doing so can improve your mental health and digestive health due to the gut-brain connection. Here are some effective ways to boost serotonin:
- Eat tryptophan-rich foods (serotonin is produced from an amino acid called tryptophan, so consuming more of this amino acid can promote serotonin release. Tryptophan-rich foods include eggs, cheese, turkey, salmon, tofu, nuts, and seeds)
- Go outside in the sunlight to promote vitamin D synthesis (vitamin D is a natural mood lifter)
- Exercise regularly in a way that you enjoy to promote the release of serotonin, dopamine, and endorphins
- Set aside time for creative hobbies that bring you joy (as with exercise, this causes the release of serotonin and endorphins)
- Socialise with loved ones (laughter and socialisation can promote serotonin release in the brain, and strengthening your personal relationships can create a positive feedback loop to cause further release of serotonin)
Manage your stress
The GBA is highly sensitive to stress. Physically stressing the body too much (by physically exerting yourself beyond your capabilities or overtraining) or being mentally stressed can disrupt the communication between the brain and gut, leading to declines in mental and digestive health.
The best stress management techniques for you depend on your unique stressors. If the cause of your stress is mainly overtraining in the gym, the resolution is to reduce the number of workouts you do each week. If it’s a jam-packed work schedule, consider cutting back on your workload or reducing the number of hours you work.
I understand how difficult it can be to reduce stress. It's not as simple as it might sound, especially if the main source of stress you're experiencing is out of your control. However, if you're serious about strengthening your gut-brain connection, it's worth trying to see what the key stressors are in your life and eliminate them (or, at the very least, reduce them).
Reduce your caffeine and alcohol intake
Caffeine can be a great mood-booster and energy-lifter, especially first thing in the morning when you're feeling groggy. However, consuming too much caffeine can cause your body to release lots of cortisol, leading to a stress response. This is particularly true if you're sensitive to caffeine, which tends to be due to your genetics and the enzyme activity in your liver.
Similarly, consuming excessive alcohol can cause cortisol release and inflammation in the gut, disrupting the gut-brain axis and leading to even more stress and anxiety. Although an alcoholic drink every now and then is absolutely fine and won't cause too much damage, continual excessive intake can be detrimental to your health. The NHS recommends that you consume no more than 14 units of alcohol per week, spread over three or more days.
Practice mindful eating
Mindful eating is the perfect way to combine healthy behaviours that benefit both your brain and gut. The mindfulness part of mindful eating refers to being in the present moment and avoiding distractions when you’re having a meal or snack.
By focusing your attention on the food in front of you and savouring every bite of food, you will naturally slow down the rate at which you eat, allowing your digestive tract to manage more easily. Eating more slowly also means you’re more likely to perceive fullness cues as soon as they arise and avoid overconsuming.
