The Gut-Brain Axis - what you eat can impact your mood

By: Joanna Foley

Scientists have discovered a clear link between the gut and brain, known as the gut-brain axis. This involves communication between the central nervous system (which includes the brain) and the enteric nervous system (which involves the digestive tract). 

The connection between your gut and brain may not seem like a likely pair. Thus, you have probably experienced some of the ways they work together in your day-to-day life. For example, getting “butterflies” in your stomach in response to nerves. In fact, the brain-gut relationship is so strong that specialists often referred to the gut as the “second brain.”

The health of your gut is strongly influenced by your microbiome, which is a collection of bacteria and other microorganisms in your digestive system. Having a proper balance of these microorganisms is key to not only healthy digestion but also brain health. Gut bacteria have been shown to produce a wide range of brain chemicals called neurotransmitters, which play a role in regulating your mood. It has been found that about 95% of the neurotransmitter serotonin is produced in your gut. Because of this, research shows that having an imbalanced microbiome, known as dysbiosis, can contribute to a negative emotional state.

How food impacts your brain

All food is made up of three macronutrients- carbohydrates, protein, and fat. It also contains micronutrients, which are vitamins and minerals. Each of these plays a crucial role in producing the neurotransmitters described above. Your brain needs access to the right types of fuel to function properly. A poor-quality diet, or one that lacks variety, leads to fewer nutrients available to produce enough of the right neurotransmitters. This, in turn, can potentially contribute to mental health concerns. Multiple studies show that healthy, balanced diets may lower the risk of depression and other mental and mood health disorders, while diets high in less healthy and highly processed foods are linked to an increased risk.

Food to promote a healthy gut and mood

Since there is a close connection between your gut and brain, what you eat can impact both. Some of the best foods and nutrients to consume to support a healthy gut and mood include:

Probiotics:

Probiotics are a type of live, beneficial bacteria that help nourish the health of your gut. In addition to improving things like digestion, research shows that probiotics may positively impact mood and mental health conditions. Food examples include fermented foods like kimchi, sauerkraut, miso, tempeh, yogurt with live & active cultures, and fermented beverages like kombucha and kefir. We can also consume high potency probiotics, which may be more beneficial due to the higher concentration and variety of beneficial bacteria strains

High fiber carbohydrates

Carbs help produce serotonin, a “feel-good” chemical in your brain—however, the type of carbohydrate matters when it comes to gut health and mood. Complex carbohydrates contain fiber, and studies show that fiber affects your microbiome positively. Some types of fiber also serve as prebiotics, which is fuel for probiotics to thrive. High fiber diets are known to help improve your gut's overall health and improve mood, including a reduced risk for symptoms of depression. Food examples include nuts, seeds, beans, and other legumes, fruits and vegetables, and whole grains like oats, quinoa, and products made with whole wheat.

Vitamins

• Magnesium is a mineral that plays a large role in both gut and brain health. Research shows that not getting enough magnesium alters the gut microbiome and can also lead to symptoms of depression and other psychiatric problems. Food examples include Almonds, pumpkin seeds, avocados, dark chocolate, leafy greens, bananas, beans, and tofu.
• Omega-3 fatty acids- These healthy fats have great anti-inflammatory properties. Since inflammation is linked to mental illness and can also interfere with the balance of your microbiome, eating foods that fight against it can positively affect mood and digestion. Omega-3 fats also support neurotransmitter production, and high intakes are linked to a reduced risk of depression. Food examples include Fatty fish like salmon, sardines, tuna, mackerel, walnuts, and seeds like chia, hemp, and flax seeds.
• B vitamins- Folate and vitamins B6 and B12 are all types of B vitamins that are required to produce vital neurotransmitters, which, as mentioned, are essential for optimal brain functioning. They also act as a host for certain gut bacteria and provide nutrients for them to thrive. Not getting enough B vitamins may lead to a greater risk of depression and other mental health disorders. Thus, interfere with the health of your microbiome. Some foods that contain vitamins B are whole grains, meat, fish, poultry, lentils, eggs, leafy greens, and dairy products.

Foods to Avoid

On the other hand, some foods can negatively affect your brain and gut, and should therefore be limited or avoided. These may include:

Added sugars

Too much sugar takes a negative toll on just about every process in the body, including the gut and brain. Excess sugar contributes to inflammation, and it can have a negative impact on psychological health. Lower sugar diets may help improve mental health. Common food sources include baked goods, desserts, sweetened beverages, highly processed and packaged foods, flavored yogurts, and condiments.

Artificial sweeteners

“fake sugar” may be just as bad as the real kind when it comes to your gut and brain. Research shows that artificial sweeteners can negatively alter the gut microbiome and are also linked to brain and mood disorders. Examples include aspartame and sucralose, commonly found in diet foods and beverages.

Caffeine and alcohol

Both of these can irritate your gut and contribute to symptoms of IBS. Too much caffeine can also worsen symptoms of anxiety and panic attacks. Research shows that alcohol can interfere with neurotransmitter production, possibly leading to mental health problems. Regular coffee and tea, most sodas, and chocolate contain coffee. Sources of alcohol include beer, wine, ciders, and hard liquors.

In Summary

Understanding the gut-brain axis helps explain how we can use food as a treatment complement. It will help optimize the health of your gut while also helping treat mood disorders. While getting nutrients from whole foods is a great option, high potency probiotics are often indicated, and working with a trained health professional can help guide supplementing. In addition, keep in mind that making changes to your diet to boost brain and gut health may work best when used in combination with other therapies like medications and counseling. So always check with your healthcare provider before considering stopping or reducing any other treatments.

Joanna Foley, RD, is a registered dietitian, freelance writer and author, and owner of joannafoleynutrition.com. She enjoys teaching others about how food impacts their bodies and helping them learn how to use food for what it is meant to be: something to enjoy, nourish and heal us.