Imagine if eating differently could elevate your mood or improve your brain and mental health. (It can!) Or if reducing stress can also reduce gut symptoms. (It does!) Sounds interesting? Learn what science says about improving mood with food!
There is a complex relationship between the food we eat and our mental health. However, since the last decade, we see an increasing number of research focused on the connection between diet, feelings, thoughts, and emotions. Many studies have been exploring the “microbiota-gut-brain axis” - a very complex connection between your gut, its microbes, and your brain. This new, very exciting field has been called a “paradigm shift in neuroscience” (Dinan, 2017).
These discoveries not only have huge potential to help people resolve their gut issues with support from the brain, but have also proven that it is possible to improve brain and mental health issues with help from the gut. Let’s explore the link between gut health, mood, and stress!
Your gut is (partially) controlled by your brain
Digestive disorders can cause pain, bloating, and many other discomforts, and they impact over 35 percent of people at some point in life - affecting more women than men. Many times, these gut issues don’t have an apparent or easily diagnosable physical cause, so they can be difficult to treat and find relief from.
We already knew that our brain controls some of our digestive processes. For example, research has found that even thinking about food and eating can cause the stomach to release gastric juices and enzymes, to get itself ready for food. Your gut is also sensitive to emotions - you may recall a time when you felt anxious and nauseous or felt “knots” or “butterflies” in your stomach.
Several studies show that stress may be an important - often overlooked - reason for gut issues. According to Harvard Health, “Stress can trigger and worsen gastrointestinal pain and other symptoms, and vice versa.”
This is why it’s so important to look at your stress and emotions if you have gut issues! Many studies have found that stress reduction techniques can lead to greater improvement in gut symptoms compared to conventional medical treatment alone.
Before we go over how to do this, let’s look at a bit more of the biology behind the gut-brain axis.
The role of your nervous system
There are two main parts of your “main” nervous system. One is the part that we can consciously control, like when we move our muscles to walk around, chew our food, or swim. This is called the somatic nervous system.
The other part of our nervous system controls all of those things that we can’t control, but need to survive. These include processes that happen automatically in the background: breathing, heart beating, sweating, or shivering. This part of the nervous system is called the autonomic nervous system (because it works automatically).
The autonomic system regulates our body’s functions by either speeding things up or slowing them down. When things are sped up, like when our “fight or flight” reactions kick in, this is done by the sympathetic part. We feel this happening when we sense danger (real or not) and get stressed. Our heart beats faster and we breathe heavier. We’re preparing to fight or flee, so our body focuses on ensuring our muscles get enough blood and oxygen to work hard.
Slowing things down, on the other hand, is done by the parasympathetic part. This happens when we’re relaxing or after the danger has passed and we start to calm down. Our heart, lungs, and muscles rest and our digestive systems do their jobs much better. In this phase, we’re secreting more digestive juices to break down food, we’re absorbing more nutrients, and we have lower levels of inflammation in our gut. That’s why this is called the “rest and digest” phase.
Both of these arms of the autonomic nervous system - the sympathetic and parasympathetic - interact with the gut. This means that when our body is stressed we can experience gut symptoms and when we’re relaxed our digestion does what it’s meant to do.
Your gut is your second brain
Here is a mindblowing fact: in addition to your “main” nervous system, your gut has its own nervous system called the enteric nervous system. The enteric nervous system spans your whole digestive tract from your esophagus, along your stomach, intestines, and colon. This nervous system is sometimes referred to as the “second brain” because it works in the same way that the “main” one does. It has 100 million nerve cells (called neurons) that communicate with each other using biochemicals called neurotransmitters.
Your enteric nervous system gets input from both the sympathetic and parasympathetic nervous systems, so it can speed up or slow down when it has to. It also has a “mind” of its own and can function independently of them.
This complex system is important because of how complex our digestive processes are. For example, after we eat, the neurons in our enteric system tell the muscle cells of the stomach and intestines to contract to move food along to the next part. As our gut does this, our enteric nervous system uses neurotransmitters to communicate with the central nervous system.
Your enteric nervous system is also very closely linked to your immune system. This is because a lot of germs and bacteria can enter the body through the mouth and end up in the gut. You have a large immune presence there to help fight them off before they become a larger problem and infect other parts of the body. In fact, over 70% of your immune system is located in your gut! The cells of the immune system provide another path for the gut to communicate up to the brain. They relay information like when they detect infection or when your stomach is bloated, so your brain knows, too.
Even the friendly gut microbes (the gut microbiota) that help us digest and make certain nutrients play a role in communicating with the brain. They make neurotransmitters, some of which are known to influence our mood.
The Gut-Brain axis
This intimate and complex connection between your gut and brain is called the gut-brain axis. And we now know that the signals go in both directions: from your brain down to your gut, and from your gut up to your brain.
This is where we see the link between digestive issues and brain, stress, and mental health.
When someone is stressed enough that they get into the “fight or flight” reaction, digestion slows right down to allow the muscles to fight or flee. The same physical reaction appears whether the stress is from a real threat or a perceived one. This means that your body reacts the same whether you’re facing a real life-threatening situation or whether you’re super-stressed about a looming deadline. This disruption of the digestive process can cause pain, nausea, or other related issues.
Meanwhile, it’s known that experiencing strong or frequent digestive issues can increase your stress levels and low mood. People with depression and anxiety have more digestive symptoms, and vice versa.
How stress and emotions affect your gut
Because of these strong connections between the gut and brain, it’s easy to see how stress and other emotions can affect the gut. Things like fear, sadness, anger, or feeling anxious or depressed are often felt in the gut. When they cause our digestive systems to speed up (or slow down) too much, this can influence pain and bloating. It can also allow germs to cross the lining of the gut and get into the bloodstream, activating our immune system. Moreover, it can increase inflammation in the gut or even change the microbiota.
This is why stress and strong emotions can contribute to or worsen a number of digestive issues such as Crohn’s disease, colitis, irritable bowel syndrome (IBS), gastroesophageal reflux disease (GERD), or food allergies or sensitivities.
Then, these gut issues are communicated to the brain, increasing the stress response and affecting our moods.
This loop of stress and gut issues and more stress and more gut issues becomes a vicious cycle.
Interestingly, recent studies also indicate that people who suffer from depression and anxiety have very different microbiomes than people who are not depressed. Patients with depression have a higher number of bad bacteria that produce inflammatory chemicals which are sent back to the brain and get distributed in the body. Our friendly microbes do more than help us digest foods, make vitamins, and protect us from the not-so-friendly microbes - the kind of bacteria we have in our gut dictates the health of our gut and it influences our body, including our brain.
So, what can we do to nurture a healthy gut and healthy brain?
How to support your gut-brain health
What you eat can have a huge impact on your health. Proper nutrition can support your body to cope with stress better, increase resilience, build strength and refill with nutrients that may have become depleted during periods of chronic stress.
Probiotics
Your gut health improves when you eat a higher-fiber, more plant-based diet, because it provides your friendly gut microbes with their preferred foods to grow and thrive. Remember, these gut bugs have an enormous effect on our brain health as well, so we want to make them happy!
It's also possible to support and repopulate our microbiota by consuming probiotic foods. “Probiotics” are live organisms that you can eat, drink, or take as a supplement. They turn milk into yogurt, and cabbage into sauerkraut; and they are great for both your gut health and mental health.
Probiotics can be found in yogurt, sauerkraut (and other fermented veggies), miso, tempeh, kimchi, kefir and kombucha.
Prebiotics
PREbiotics are food for gut microbes and, when fermented in the gut, produce specific changes in bacterial composition or activity. They are your friendly gut microbes’ favorite delicacies so they’ll happily grow, and multiply. Prebiotics are basically foods that contain fiber. Things like fruits, vegetables, nuts, and seeds. Even dark chocolate (preferably with at least 70% cocoa). Foods that are particularly high in prebiotics include apple, banana, flax seed, asparagus, avocado, whole grains, and allium vegetables like onions, garlic, leeks, and shallots.
Omega-3 Fatty Acids
Omega-3 fatty acids are polyunsaturated fats that have numerous mental health benefits. These fatty acids are vital for the maintenance of good brain function as they help in preserving cell membrane health while also facilitating the communication between brain cells.
Numerous studies show that consuming omega-3 fatty acids reduce markers of psychological and physiological burnout, including decreased cortisol levels. In addition, recent clinical studies have concluded that taking fish oil supplements can improve depression symptoms significantly - the effects of fish oil supplements were similar to those of antidepressant medication.
Sources of Omega-3 Fatty Acids:
Oily fish such as salmon, mackerel, herring, and sardines
Plant-based sources: walnuts, chia seeds, flax seeds, hemp seeds
You can consider supplementation of omega 3 fatty acids – in form of fish oil or a vegan alternative (synthesized from algae) - always check with your healthcare provider
Tryptophan
Tryptophan is an essential amino acid our brain is using to produce serotonin, a neurotransmitter that helps us to sleep better, relieve depression and anxiety symptoms, stabilize our mood, and is responsible for our overall emotional wellbeing.
There is an abundance of tryptophan found in meat-based sources, such as chicken, turkey, red meat, pork, fish, milk, and eggs.
Plant-based sources include edamame beans, tofu, pumpkin seeds, sunflower seeds, red kidney beans, oats, buckwheat, cashews, spinach, other nuts and seeds.
Magnesium and Vitamin B6
Research indicates that Magnesium and Vitamin B6 may be supportive against stress. A recent study showed that combined supplementation helped to alleviate stress levels in individuals who were experiencing chronic, long-term stress.
Sources of Magnesium:
Green leafy vegetables, nuts and seeds, dark chocolate (70% and up), avocados, legumes
Epsom salt baths are a good way to increase Magnesium levels
You can consider taking a multivitamin and mineral complex daily, which includes magnesium, or Magnesium in another form, such as oral spray (always check with your GP)
Sources of B6 include tuna, salmon, poultry, chickpeas, banana, organ meats, tofu
Avoid highly processed foods as much as you can
Highly processed foods that are high in trans fat, saturated fat, refined flours, and sugar are linked to higher levels of inflammation.
Processed food has chemical substances in order to be preserved longer, but also to look and taste better. By eating processed food, we are consuming substances such as preservatives, additives and artificial ingredients that our body isn’t designed to process.
Not all food that has been under some type of process is harmful to our body, but chemically processed foods (also known as ultra-processed foods) are usually high in artificial ingredients, refined carbohydrates, sugar, and trans fat.
These foods have been linked to various chronic conditions (diabetes, cardiovascular disease, obesity, etc) as well as increased rates of anxiety and depression.
Processed foods to avoid: sweets, white bread, and pasta, white rice, pre-packaged foods, biscuits and cakes, fast food
Eat wholegrain alternatives: wholemeal pasta, wholegrain bread, wholegrain cereals, brown basmati rice, oats, quinoa, buckwheat, millet, couscous etc.
Also try reducing dependence on stimulants – i.e. coffee, tea, colas, energy drinks and cigarettes. Rather than giving energy, these deplete energy over time, and contribute to blood sugar imbalances. Try swapping coffee and breakfast tea for green tea as research evidence suggests that green tea extract enhances cognitive functions, in particular the working memory.
Excercise
Aerobic exercise helps counter stress by boosting the body's endorphins (natural feel-good chemicals), using up stress hormones, protecting brain cells, and lowering blood pressure. Evidence suggests that long-term stress impairs immune function and makes us more vulnerable to disease, but regular moderate exercise has been shown to be beneficial for immune function. Just don’t overdo it! Aim for around 150 minutes per week of moderate-intensity activity.
Stress-reduction techniques
Evidence suggests that some stress reduction techniques and/or psychotherapy may help people who experience gut issues. They can lower the sympathetic “fight or flight” response, enhance the parasympathetic “rest and digest” response, and even reduce inflammation.
Some beneficial stress-reduction techniques: guided meditation, deep breathing, mindfulness, relaxation (e.g. aromatherapy, massage, a walk), yoga
Your gut, brain, and mood will thank you!
Bottom Line
Our bodies are incredibly complex and different parts interact on so many levels. The gut-brain axis is a prime example! The gut and brain are more interconnected than we previously thought, which opens up new opportunities to improve our mental health, brain function, and overall wellbeing with better food choices.
Want a plan to help you eat - and enjoy - more of the foods that help your gut, brain, and mood? Are you looking for a way to incorporate more "mood foods" into your diet? I can help! Reach out below for personalized research-based nutrition advice for your health, lifestyle, and goals!
Sources & Further Reading
Cleveland Clinic. (2016, October 6). Gut-Brain Connection. Retrieved from
Harvard Health. (n.d.). The gut-brain connection. Retrieved from
Harvard Health. (2019, August 21). Stress and the sensitive gut. Retrieved from
Harvard Health. (2019, April 11). Brain-gut connection explains why integrative treatments can help relieve digestive ailments. Retrieved from
University of Calgary. (2018, December 1). Can a meal be medicine? How what we eat affects our gut health, which affects our wellness. Retrieved from
Nazario Brunilda. December 15, 2009. How Food Affects Your Moods. WebMD. https://www.webmd.com/food-recipes/features/how-food-affects-your-moods
The Microbiome. Harvard, School of Public Health. https://www.hsph.harvard.edu/nutritionsource/microbiome/
September 14, 2021. Diet and Mental Health. Mental Health Foundation. https://www.mentalhealth.org.uk/a-to-z/d/diet-and-mental-health
Rao, T. S., Asha, M. R., Ramesh, B. N., & Rao, K. S. (2008). Understanding nutrition, depression and mental illnesses. Indian journal of psychiatry, 50(2), 77–82. https://doi.org/10.4103/0019-5545.42391
Pearson Keith. December 5, 2017. How Omega-3 Fish Oil Affects Your Brain and Mental Health. Healthline. https://www.healthline.com/nutrition/omega-3-fish-oil-for-brain-health
Pouteau, E, et al., 2018. Superiority of magnesium and vitamin B6 over magnesium alone on severe stress in healthy adults with low magnesemia: A randomized, single-blind clinical trial. PLoS One, 13 (12). Available at: <https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC6298677/>
Jangharad, L, 2019. Omega-3-polyunsatured fatty acids (O3PUFAs), compared to placebo, reduced symptoms of occupational burnout and lowered morning cortisol secretion. Psychoneuroendocrinology. Available at: <https://pubmed.ncbi.nlm.nih.gov/31382171/>
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