Your brain is a wonderfully complex organ that acts as a control center for your body and your mind. It’s responsible for everything from your emotions to your ability to move your body to your intellect and ability to reason, plan, and remember information and experiences. Seeing, smelling, tasting, and feeling are also controlled by different areas of your brain. Your beating heart and digestion are also controlled by your brain. All this to say — your brain is pretty important!
There are certainly things you can do to keep the brain in tip-top shape like exercising daily, sleeping well, staying mentally active, and connecting with others (spreading love works wonders for your brain!). Research shows that food may also play a big part in nourishing the brain. The foods you eat can either support or hinder your brain’s ability to function. And, if your brain isn’t functionally well, then, as you may guess, the organs it controls may not function so well either (hello, heart, eyes, and digestion!). In fact, the food you eat is so powerful, that scientists now consider your gut to be your “second brain.”
The Gut: “The Second Brain”
Research is discovering more and more about the connection between the gut and the brain. (Nerd alert — it's fascinating!) The brain communicates through the spinal cord. Most likely, you’ve heard of the central nervous system. The brain and spinal cord make up the central nervous system. Nerves, neurons (nerve cells), and neurotransmitters travel through the spinal cord and communicate to the organs. There’s another nervous system that is less well-known, called the enteric nervous system, which travels along the entire gastrointestinal tract, from the esophagus to the stomach to the intestines and down to the anus. The enteric nervous system relies on the same chemical messengers as the central nervous system, therefore scientists have given it the name, “the second brain.” (Intermission question: At this point, are you fascinated 🙋🏻♀️ or yawning with boredom🥱? Hang in there ... a little more science before getting to the juicy, "just tell me what to do" stuff.)
The Gut-Brain Axis
Because the gut communicates with the brain, it piqued the interest of researchers to study how it may play a role in mental health and lifestyle diseases. The connection between your gut and your brain is called the gut-brain axis. Scientists call this “crosstalk” because the gut and the brain communicate with each other through the nervous system, immune system, and hormones. This relationship between your gut and your brain is part of the reason why your stomach gets queasy when you are anxious, or why you may feel sleepy after a heavy meal.
Another example lies in the case of anxiety. If you’ve ever experienced anxiety, or just nervousness, that appears to stem from your mind, you may have experienced feelings of discomfort in your gut at the same time. This anxiety or nervousness could also lead to digestive issues. On the other hand, gastrointestinal disorders may cause anxiety and stress. It’s a two-way street. When you experience GI issues, the brain may be affected and when you're feeling psychological stress in your head, your gut may be affected.
Food for thought: The link between diet and brain health
Within the gut, there are over 10 trillion different types of microbes that are meant to live in harmony with your body. These microbes include bacteria, yeast, fungi, and other microorganisms. Your body creates a friendly environment and you (hopefully!) eat food that feeds the microbes. Having diverse bacteria is important for gut health and overall health, and what you eat can influence that diversity. A healthy gut can help to regulate your hormones, immune system, and metabolism. It can protect the lining of your intestines, creating a strong barrier against toxins, reduce inflammation, and help absorb nutrients. Scientists are discovering that a healthy gut may also regulate “crosstalk” or communication with the brain.
For example, you may be surprised to learn that more than 90% of your body’s serotonin, your "feel-good" hormone, is produced in the gut, while only 10% is produced in the brain. Your gut microbiome can influence the creation of serotonin. Interestingly, research shows that individuals who experience gastrointestinal disorders, like irritable bowel syndrome or constipation, may produce less serotonin and have higher rates of anxiety and depression. Studies also show that several species of gut bacteria may be missing in people with depression, and that imbalances in gut microbes may lead to mood imbalances.
When you eat foods that support microbial diversity, or healthy bacteria to grow, your brain is supported, hormones are balanced, and metabolism is efficient. When you eat foods that either starve healthy bacteria or feed bacteria that isn’t good for your health, you may experience mood disorders, blood sugar swings, or sluggish metabolism.
Key take-home point: Taking care of your gut health is critical for brain health.
Depression and Anxiety
According to the World Health Organization, depression affects approximately 280 million people worldwide. Many of those individuals may also suffer from anxiety. This not only affects mental health, but also, overall quality of life. Anxiety is characterized by an uneasy feeling about the future, including fear and uncertainty. Research shows that both of these disorders are triggered by the interaction of psychological, environmental, genetic, and biological factors. While there are medical treatments available, they may come with side effects, like mood swings, sleep disruptions, dependence risk, and adverse reactions in other areas of the body.
Thankfully, since diet plays an integral role in health that includes managing inflammation and creating neurotransmitters, research is now looking at how what you eat may affect mood and mental health disorders (keep reading, more details below).
Cognition
Your diet can also impact how effectively your brain functions. Cognitive function is defined as “the performance of the mental processes of perception, learning, memory, understanding, awareness, reasoning, judgment, intuition, and language.” Research exploring the relationship between the gut microbiome and cognitive function is still largely pre-clinical; however, there have been numerous studies suggesting good gut bacteria may be beneficial for cognitive functioning.
What to Eat for Mood and Cognition
First, the not-so-good news (Sorry! You knew it was coming. 🤗)
The western diet is high in processed foods, meat, and dairy. These foods are high in saturated fat, salt, refined carbohydrates, sugar, while also low in fiber and phytonutrients (plant compounds that are anti-inflammatory).
The western way of eating is associated with what's called dysbiosis, an imbalance of bacteria in your gut, which may lead to inflammation, the development of lifestyle diseases (like heart disease and diabetes), and impairment of brain health (like mood disorders and cognitive decline). The western diet has been associated with decreased microbiome diversity, elimination of good gut bacteria, and increased amounts of unhealthy gut bacteria. One study showed that people consuming a western diet experienced negative changes in their gut microbiome in as little as four days.
What to Eat to Support Your Brain
Fostering a healthy gut
First and foremost — fiber.
Fiber is the foundation of a healthy gut, allowing healthy bacteria to flourish. Getting at least 30 grams of fiber a day will help to create an environment where healthy bacteria can thrive, optimizing gut health and brain health.
Your brain’s preferred direct source of energy is carbohydrates. Your gut microbe's preferred source of energy is fiber. When bacteria chomp away on fiber, they produce what's called short chain fatty acids (SCFA), which regulate food intake, change the brain’s learning pathways (neuroplasticity), and support the immune system. Low SCFA production has been associated with increased inflammation, triggered immune responses, and low serotonin production.
Foods that have been shown to support diverse and healthy bacteria are plant-based foods because they contain various types of fiber that allow healthy bacteria to flourish, supporting overall body and brain health.
Eating more of these foods will support brain health, including cognition, mood, memory, and communication with other organs (therefore, overall body health):
bean, peas, and lentils
nuts
seeds
leafy greens
cruciferous veggies (broccoli, cauliflower, radish, for example)
fresh fruit
whole grains
Prebiotics
Prebiotics are defined as "nondigestible food ingredients that promote the growth of beneficial bacteria." Prebiotic compounds feed healthy bacteria in the gut. Some types of fiber can be classified as prebiotic because they serve as food for bacteria. The polyphenol that gives blueberries their blue color also serves as a prebiotic — certain types of your healthy bacteria love it!
Boost your prebiotic intake through:
beans
lentils
oats
bananas
berries
garlic
onions
dandelion greens
asparagus
artichokes
Probiotics
Studies show that consuming fermented foods with live probiotics may improve symptoms of anxiety, depression, and other mental health issues in the general population and in people who have a clinical diagnosis. Your individual microbiome can affect the efficacy of probiotic use for supporting mental health. (Support that microbiome through ... you guessed it — fiber!)
Probiotics can be found in:
plant-based yogurt (choose unsweetened and add fresh fruit as a natural sweetener since the sugar in flavored yogurt can disrupt the gut microbiome)
miso
sauerkraut
plant-based kefir
kimchi
kombucha
And other fermented foods that state "live cultures" or "living bacteria"*
*Note that pasteurized foods or other heated foods won't contain the healthy bacteria since heat destroys them. If you want the probiotic benefits, look for living cultures.
Bottom line: Eat adequate fiber (at least 30 grams a day) plus fermented foods to start building a good microbiome base.
Polyphenols
Polyphenols are phytonutrients that act like antioxidants, exhibiting anti-inflammatory properties that may protect your brain and cells throughout your body. Several studies link polyphenol intake with lower rates of depression.
Polyphenols can be found in:
fruit and vegetables
citrus
cacao (or dark chocolate with greater than 70% cacao solids)
spices (like turmeric, black pepper, saffron, red pepper flakes, oregano, and rosemary)
whole grains
nuts
extra virgin olive oil
red wine
coffee (be mindful of how much sugar and cream you add in)
green tea
Omega 3 Fatty Acids
Omega 3 fatty acids have been associated with a reduced risk in developing depression and other inflammation-related disorders that may affect the brain. This is because omega 3’s are a type of polyunsaturated fatty acid that is involved in neurotransmitter creation, brain membrane integrity, and stress regulation.
Plant-based omega 3’s can be found in:
chia seeds
flax seeds
walnuts
hemp seeds
Brussels sprouts
Note: If you're eating an all or mostly plant-based food diet (and excluding fish), you may want to consult with a dietitian about taking an algae-based omega-3 supplement. The type of omega 3's in plants (ALA) is different from the type of omega 3's the brain needs to thrive (DHA) and the conversion of ALA to DHA is very low. For extra reassurance, I often recommend a direct DHA supplement in addition to the healthy options listed above.
Bottom Line
To support brain health, minimize foods that may disrupt gut health (like processed foods, sugar, meat, and dairy) and add more foods that increase microbe diversity, like beans, peas, lentils, vegetables, nuts, seeds, fruits, and whole grains. Check out our article 10 Fun Facts About Fiber and How to Boost it For Health here and 10 Simple Swaps to Boost Fiber Intake and Your Health here.
Find recipes that support gut health here.
Do you or someone else that you know need help?
If you, or someone you care about, are feeling overwhelmed with emotions like sadness, depression, or anxiety, or feel like you want to harm yourself or others:
Call 911.
Visit the Disaster Distress Helpline, call 1-800-985-5990, or text TalkWithUs to 66746.
Visit the National Domestic Violence Hotline or call 1-800-799-7233 and TTY 1-800-787-3224.
SAMHSA’s National Helpline, 1-800-662-HELP (4357) or TTY: 1-800-487-4889
Article assistance by Shani McLean
Hi! my name is Shani McLean, and I am a student at Georgia State University in the Coordinated Program in Dietetics. As an RD-to-be, I aspire to help folks use food to reach their wellness goals. When I’m not in the classroom, you can find me on my yoga mat or in my kitchen trying out new recipes!