The Gut-Brain ConnectionHow Gut Health Impacts Mental Health

What is the gut-brain connection?

The gut-brain connection, sometimes called the gut-brain axis or the mind-body connection, is a two-way communication channel between your brain and digestive system. Since the two are linked, an impact or change on one can directly influence the other.

You may have noticed that when you feel nervous or excited, you experience the physical sensation of “butterflies” in your stomach. Or how feeling anxious or stressed can lead to stomach issues like nausea, bloating, and diarrhea.

In the reverse signaling direction, eating different foods can directly impact your mood. When you eat a sugary treat, for example, your gut produces dopamine, giving you that “feed-good” sensation afterwards. Similarly, when you experience chronic inflammation in your stomach or have an imbalance of gut bacteria, it can cause you to feel stressed, anxious, or even contribute to a mood disorder such as depression.

The signals sent back and forth between your brain and gut occur through your vagus nerve. When this gut-brain connection is disrupted, it can impact your immune system, lead to digestive issues such as cramps, acid-reflux, and irritable bowel syndrome (IBS), and exacerbate emotional stress and mood disorders.

By gaining a deeper understanding of the gut-brain axis, you can learn strategies to improve your gut-brain connection and improve both your physical and mental health.

What is the purpose of the gut-brain connection?

Your gut and brain work together to keep your body functioning properly, ensuring your body gets the nutrients it needs while avoiding something that could be dangerous. If you’ve ever eaten something that’s made you sick, the gut-brain connection will likely ensure that you remember it the next time.

The gut and brain communicate with one another via the nervous system, impacting your body’s hormonal, metabolic, and immune systems. Specific purposes of the gut-brain connection include:

Digestion. Signals between your gut to your brain manage your appetite, signaling when you’re hungry and when you’re satiated. They also communicate food preferences, intolerances, and cravings, and help to digest food and absorb nutrients.

Mood. Stress or anxiety can impact your gut, triggering stomach irritation, impairing nutrient absorption, and intensifying the pain and inflammation of conditions such as irritable bowel syndrome. Similarly, changes in your gut health can trigger changes in your mood and outlook.

Pain and immune system. Your gut and brain communicate when you experience pain, injury, and inflammation in your body. Your gut can influence your sensitivity to pain, as well as your immune function.

Cognitive function. Your gut communicates inflammation to the brain which in turn can affect cognitive function. A healthy gut may help reduce inflammation, improving how well you think and focus, and reducing the risk of neurodegenerative conditions, such as Alzheimer’s disease.

How are the gut and brain connected?

When you talk to a friend on the phone, you have a direct two-way communication channel where you can share your thoughts and feelings. The gut-brain axis works in a similar way, but instead of using words over the phone, your gut and brain communicate through nerve, chemical, and hormone signaling.

When you see a food you love, for example, your brain lights up with excitement, triggering the release of ghrelin, a hormone that increases your appetite. Once you’ve eaten, the nutrients from the food directly influence your gut’s microbiota. In turn, your microbiota can affect your mood, immunity, and brain signaling function. If you’ve ever overindulged in junk food, for example, you may have felt sluggish afterwards.

A healthy gut can enhance the absorption of nutrients, whereas an unhealthy one may negatively impact the nutrients you absorb.

The vagus nerve

The vagus nerve connects the brain’s central nervous system to the gut’s enteric nervous system. It is the main pathway where communication between the two organs takes place. When the vagus nerve is activated through deep breathing, it can calm your mind and gut, reducing stress and improving digestion.

The gut is full of sensory nerve cells that monitor the gut’s health. When these nerve cells detect inflammation or changes in gut bacteria, they use the vagus nerve to signal these changes to the brain.

The enteric nervous system

The enteric nervous system is the gut’s very own nervous system. It earned its nickname, the “second brain,” because it comprises more than 100-500 million nerve cells, just as many as the spinal cord, and functions independently from the brain. While your enteric nervous system communicates with your brain, it can assess the health and functionality of your gut and respond independently of the brain.

Neurotransmitters

Your gut produces various neurotransmitters, which are chemical messengers that allow your nerve cells to communicate about things like muscle contraction, pain signaling, mood regulation, or digestion function.

Some examples of the neurotransmitters produced in the gut and their role in the body include:

• Gamma-aminobutyric acid (GABA) reduces stress and anxiety and promotes relaxation.
• Serotonin increases feelings of well-being and happiness, helps regulate sleep, digestion, and bowel movements, and synthesizes melatonin, the sleep hormone.
• Dopamine increases feelings of pleasure and motivation.
• Histamine regulates appetite and cognitive function and triggers an immune response when inflammation or an allergic reaction occurs.
• Acetylcholine supports cognition, memory, and muscle control.
• Norepinephrine regulates your fight-or-flight response, increasing blood flow, alertness, and focus.

When it is healthy, your gut sends positive signals and feedback to your brain. However, if your gut isn’t functioning well, it can negatively impact your mood and mental health. Similarly, when your mood and mental health are not functioning well, your brain sends negative feedback to your gut, which can impact your gut’s ability to digest and absorb nutrients from food.

Gut microbiome

Your gut is home to trillions of bacteria. These bacteria collectively make up your gut microbiome. While they play a role in digestion, they also send communication signals to your brain, directly impacting your emotions, mental health, and behavior.

A healthy balance of bacteria in your gut helps keep your gut and brain functioning properly. However, a disturbance in your gut microbiome, sometimes called dysbiosis, can significantly impact your mental health and digestive system.

Dysbiosis has been associated with conditions such as anxiety, depression, irritable bowel syndrome, and other gastrointestinal disorders. Because your gut has its own nervous system, it can directly influence your emotions by creating and sending signals to your brain.

An emotion that starts in the brain can affect your gut’s bacteria. In turn, your gut’s bacteria can communicate back to the brain, reinforcing the emotion you first felt. Sometimes, this prolongs the emotional state you’re in, exacerbating the stress or anxiety you feel.

Hormones

Endocrine cells are responsible for producing and releasing hormones into your bloodstream. There are more endocrine cells in your gut than any other organ., and they can create and release up to 20 different types of hormones.

While serotonin, dopamine, and norepinephrine are neurotransmitters, they also function as hormones. Serotonin, specifically, impacts your mood, sleep, and digestion, and your gut stores 95 percent of your body’s serotonin. What you eat can directly influence serotonin-containing cells, meaning what you eat can affect your mood, sleep, and digestion.

Other hormones present in the gut include:

• Melatonin is important for regulating sleep-wake cycles and reducing oxidation and inflammation in the body.
• Ghrelin, known as the “hunger hormone,” tells the brain when you are hungry.
• Leptin sends signals to your brain when fullness or satiety is reached.

Some researchers suggest that your gut microbiome can significantly affect energy balance and weight management. Since your gut’s hormones impact feelings of hunger and fullness, gut bacteria can influence how much you eat in a day, and thus impact your weight.

Gut health and mental health

Research has shown links between mental health conditions such as anxiety, depression, stress, ADHD, autism, and Alzheimer’s disease, and gut disruptions like dysbiosis and irritable bowel syndrome.

An imbalance in your gut microbiome can cause issues with nutrient absorption, a weakened immune system, and mental health issues. Similarly, your gut microbiome can be easily influenced by your mental health, immune function, antibiotic use, and diet. This means that what you eat can directly impact your mood and mental well-being.

As researchers continue to investigate the links between gut health and mental health, we are learning that ultra-processed foods may be linked to compromised mental health, including increased instances of depression and disordered eating. Though you may know ultra-processed foods are not healthy alternatives to whole foods, when you are stressed or anxious, you’re more likely to crave eating these comfort foods. It’s possible these foods can alter gut microbiota, causing inflammation and further exacerbating issues like depression, IBS, and acid reflux.

Tips to improve your gut-brain health

Improving your gut-brain health does not have to be overwhelming or complicated. The goal is to diversify the abundance of gut bacteria to promote a healthy gut microbiome. Having a diverse microbiome means more resilience and less vulnerability to mental health or gut disturbances.

How do you diversify your gut bacteria? Set yourself up for success by eating nourishing foods and managing your mental health through self-care strategies. The following tips offer simple ways to improve both your mental and gut health.

Tip 1: Eat more fiber

Dietary fiber plays a significant role in your gut health. It serves as an energy source for the bacteria living in your gut, is associated with improved gut motility and colon function, and supports your gut’s immune function. Some research points to the potential link between a low-fiber diet and a weakened gut lining, increasing susceptibility to infection.

Increasing the fiber in your diet can increase the diversity and function of your gut microbiota. In the U.S., the FDA recommends eating 14 grams of fiber per 1000 calories. For the average adult, that’s 28 grams per day.

Slowly increasing your fiber intake will help you avoid drastic bowel movement changes. Start with an additional five grams daily until you work up to the recommended daily amount.

Opt for whole grains. Whole grains contain more fiber, vitamins, and minerals than refined wheat products. Check the ingredient list when purchasing bread, pasta, or crackers to ensure you’re getting whole grains. You want to see that the first ingredient says, “whole wheat” or “whole grain.”

Incorporate more fruits and vegetables into your diet. Fruits and vegetables of all kinds are rich in fiber. Some good options include passion fruit, berries, pomegranate, green peas, broccoli, and Brussels sprouts. To optimize your fiber intake, keep the skin on options like pears, apples, carrots, and potatoes.

Increase your legume and bean intake. Lentils, chickpeas, beans, and soybeans are just a few examples of legumes that provide a rich source of fiber. There are many ways to incorporate these foods into your meals, including in rice bowls, in tacos, as a hummus spread, or on top of a salad.

Top with chia and flaxseeds. Though small, chia and flaxseeds are mighty fiber sources. A little goes a long way, and just 1 tablespoon of either seed contains about three grams of fiber. Top your yogurt, oatmeal, smoothie, or salads with chia or flaxseeds to boost your fiber intake.

Tip 2: Add probiotics to your diet

Probiotics are living bacteria that support your gut’s digestion and immune function. They play a role in maintaining or restoring the balance of bacteria in your gut, impacting your overall health and well-being.

Maximizing your probiotic food intake can contribute to a diversified gut microbiome, improving nutrient absorption, the strength of your gut’s lining, your body’s defense against inflammation, and even your brain’s response to negative emotional or stress triggers.

Choose probiotic foods like yogurt, kefir, kombucha, and soft cheeses. These foods have live bacteria cultures to support your gut’s microbiome. Consider adding yogurt or kefir to a smoothie, or enjoy a low-to-no-added sugar kombucha beverage.

Eat fermented foods. Incorporating foods like sauerkraut, kimchi, tempeh, and miso into your diet can boost your probiotic intake. Note that the bacteria need to be alive in the fermented food for you to gain any gut benefits. While beer and wine are fermented, they do not contain live bacteria.

Pair with prebiotic foods. Prebiotics are fiber that feeds the bacteria in your gut, supporting their growth and function. Pair your probiotic foods with prebiotic-containing foods like fruits, vegetables, whole grains, seeds, and legumes to ensure your gut bacteria both has its food source and maintains its functioning.

Make it a consistent habit. Reap ongoing gut health benefits by consistently incorporating high-fiber foods. Aim to have a fiber source at every meal and snack to keep your gut bacteria happy and healthy.

Limit antibiotic use. While antibiotics eliminate bacterial infections, they also wipe out your good bacteria. Long-term use of antibiotics can disrupt your gut’s microbiome and negatively affect your gut and mental health. When taking antibiotics, follow the prescription strictly and consider incorporating probiotic foods or a probiotic supplement to replenish your gut’s good bacteria.

Tip 3: Limit “junk” or processed food

Diets high in unhealthy fat and added sugar may increase gut permeability, dysbiosis, and inflammation. Additives and emulsifiers in processed foods may disrupt your gut bacteria and cause inflammation and oxidative stress. While you don’t need to completely eliminate processed food from your diet, limiting it and focusing more on eating whole foods can benefit your gut and brain health.

Shop the store perimeter. Aim to get the bulk of your groceries from the grocery store’s perimeter. You can still get nutrient-dense items in the aisles, like beans, whole grain products, and broths, but fresh produce, lean meats, and probiotic-containing products are usually located around the perimeter.

Read labels. When purchasing packaged foods, look at the nutrition facts label to understand the nutritional value. Consider choosing options with higher fiber, lower added sugar, and lower saturated fat. Look at the ingredients list and aim for products limited in additives, emulsifiers, artificial coloring, and alternative sweeteners.

Plan out your meals ahead of time. Knowing what you want to prepare and eat ahead of time can help reduce impulse food decisions. If you wait until you’re hungry to decide what you want to eat, you’re more likely to choose something convenient rather than nutritional.

Be aware of marketing tricks. Food companies often use crafty marketing strategies to entice you to buy their products. They may use words like “natural” or “gluten-free” to convince you their product is healthy. Remember to read the labels to decide for yourself.

Incorporate healthy fats and lean proteins. Eating omega-3 fats from foods like fatty fish, olive oil, nuts, seeds, and avocados may help support your gut’s lining and reduce inflammation. Lean proteins, lower in saturated fat compared to red meats, like chicken, turkey, and fish, may help repair and strengthen the gut’s lining and aid in gut immunity. Eating healthy fats and lean proteins can also contribute to the diversity of bacteria in your gut.

Tip 4: Moderate alcohol and nicotine

The more we learn about the gut microbiome and gut-brain axis, the more we uncover the potential negative impacts of alcohol and nicotine.

Overusing alcohol can disrupt your gut bacteria and increase instances of inflammation and intestinal permeability, known as leaky gut syndrome. Some research suggests reducing alcohol intake may help improve your gut bacteria diversity and overall gut function.

Smoking has also been shown to reduce microbiome diversity. Quitting smoking may have positive impacts on both the gut microbiome and inflammation.

Set your limits. If you’re looking to cut back on alcohol intake, establish some boundaries for yourself. Consider cutting your intake in half or limiting intake to one or two days per week. When you do consume alcohol, alternate with water or other nonalcoholic beverages to help reduce your intake.

Incorporate healthy substitutes. Sometimes, replacing one habit with another can be easier than simply dropping a bad habit. If you’re looking to cut back on alcohol, try non-alcoholic beer or wine or other beverages like kombucha, tea, or flavored waters. Or, instead of going to the bar, try out a new hobby that doesn’t involve drinking. Instead of reaching for a cigarette, try a stress management technique instead, such as meditation or a breathing exercise.

Avoid triggers. If you’re looking to cut back on drinking or quit smoking, remove temptations from your house. Set up social outings with friends that don’t involve alcohol, or that take place at a non-smoking location.

Establish social boundaries. Share your goals with loved ones and set boundaries for what you are and are not willing to partake in. Establishing boundaries with others will help reduce social pressures to smoke or drink beyond the limits you’ve set for yourself.

Tip 5: Strengthen your vagus nerve

Simulating the vagus nerve has been shown to improve digestion and gut permeability and reduce inflammation, oxidative stress, and pain perception. While medical therapies can stimulate the vagus nerve, you can also do things at home to strengthen it.

Incorporating some of the following tips regularly may help alleviate any stress, anxiety, or gut issues you’re experiencing.

Practice deep breathing. Incorporate moments of deep, slow breathing exercises throughout the day, especially when you feel stressed. This type of breathing can help stimulate your vagus nerve, regulate your heart rate, and reduce feelings of anxiety.

Prioritize quality sleep. Aim for seven to nine hours of sleep each night. To increase the quality of your sleep, reduce outside noise or light and keep your room at a comfortable temperature.

Exercise regularly. The American Heart Association recommends adults get 150 minutes of moderate or 75 minutes of vigorous activity per week. While exercise has heart health benefits, it also has mental and gut health benefits. Schedule regular movement into your week. Opt for an activity that you enjoy, and increase the fun by inviting a friend to join.

Listen to music. Music can stimulate the vagus nerve, so play your favorite tunes and sing along, or go see live music with loved ones. Consider taking singing lessons or learning how to play a new instrument.

Plan time for hobbies, fun activities, and time with friends. Light-hearted activities can boost feelings of joy and relieve stress, positively impacting mental and gut health.

Gut-brain connection

Your gut and brain are closely connected through your gut bacteria and nervous, endocrine, and immune systems. The gut-brain pathway allows your gut and brain to influence one another.

When you support your health through diet, exercise, and stress management, you positively impact both your mental health and gut health. Supporting your mental health positively influences your gut health by promoting a diverse gut microbiome and reducing inflammation and gut permeability. When your gut health is supported, it can benefit your mood, cognition, and behavior.

With a greater understanding of the gut-brain connection and ways to positively influence it, you can begin implementing more ways to support this complex and profoundly influential connection.