We know that the brain plays a key role in all of our bodily functions – it’s the center of our intelligence and the controller of our movements and behaviors. But did you know that you have a “second brain”? This second brain is found in your gut. Beyond digestion, your gut contains an extensive network of neurons and an elaborate microbiome that can determine your mental state and risk for neurological conditions.
The connection between the brain and the gut involves the vagus nerve, which serves as a channel of communication between the nerve cells in the intestinal nervous system and the central nervous system. A major contributor to this communication is the bacteria in our gut – all 100 trillion of them. To put this into perspective, it is estimated that the average human body contains 37.2 trillion cells. We are significantly outnumbered by these microbes, which play a role in the production of several neurotransmitters.
First, they influence the production of serotonin, otherwise known as the “feel good” neurotransmitter. It is estimated that up to 90 percent of all serotonin production comes from the second brain in our gut. Imbalances in this neurotransmitter have been linked to increased risk of depression, as well as other health concerns.
Second, gut bacteria produce an amino acid called GABA, which helps to calm nerve activity after a state of stress. Finally, gut bacteria produce a neurotransmitter called Glutamate, which affects cognition, learning, and memory. Deficiencies of these chemicals have been linked to a number of mental disorders and diseases.
Beyond the production of these important brain chemicals, the gut microbiome plays an important role in digestion, through the fermentation and absorption of carbohydrates. The good bacteria in our gut help to suppress the growth of harmful bacteria that could lead to illness. The gut microbiome is also an integral part of our immune system. Armed with this knowledge, how do we keep our gut microbiome functioning in a way that supports good health?
Everyone has a unique microbiome and digests food differently. A good first step is to determine which foods your body tolerates well and which foods it might be sensitive to. Food sensitivities and intolerances are different than food allergies, which involve the immune system and produce an acute reaction to a food that someone is allergic to. A sensitivity or intolerance, on the other hand, occurs when the digestive tract is not able to properly break down and digest a certain food or food component. Some common intolerances and sensitivities include the following:
- Tyramine (especially linked to migraines)
- Food preservatives and additives
This list is certainly not all-inclusive. Sensitivities and intolerances can vary from one person to another. In addition, symptoms of a sensitivity can vary, including brain fog, headaches, fatigue, reflux, joint pain, skin issues, and digestive distress such as gas, bloating, and constipation.
One way to identify if you are sensitive to something is to do an elimination diet. To do this, you can either eliminate several foods at once, or just one food at a time, usually for 3–6 weeks. Then add back each food individually and monitor how you feel with and without the food in your diet. This method of trial and error is one of the best ways to determine any individual food intolerances.
Keep in mind that even though you might be able to get away with eating a food you are sensitive to, on the inside it is wreaking havoc in your gut, creating inflammation that can directly affect the health of your brain.
After determining any sensitivities, it’s time to start incorporating foods that can boost the health of your gut! Here are some foods to prioritize:
- Foods rich in probiotics: Probiotics are live bacteria that can improve the number and diversity of the bacteria in your gut. While you can find these in supplement form, it is always better to emphasize food sources first. Fermented foods such as live-culture yogurt, kefir, kombucha tea, kimchi, sauerkraut, and pickles all contain healthy bacteria (including bifidobacteria and lactobacilli) that can improve the health your gut lining and help control inflammation.
- Foods low in sugar and high in fiber: A high sugar diet has been linked to increases in negative bacteria in the gut. Sugar is also inflammatory, and elevated blood sugar due to insulin resistance is implicated in Alzheimer’s Disease. Try to eliminate as much added sugar as possible. On the other hand, getting in 30-40 grams of fiber every day helps feed beneficial bacteria in your gut. Incorporating 8-10 servings of fruits and vegetables every day can help you reach that goal.
- Make dark chocolate, coffee, and tea a part of your daily routine. Flavonols in dark chocolate have been linked to improved cognitive function. Coffee is a rich source of antioxidants and can contribute to a healthy balance of gut bacteria. Black and green tea can increase bifidobacteria in the gut and may potentially decrease harmful bacteria.
By ruling out food sensitivities and incorporating these gut-friendly foods, you can keep your brain and your “second brain” healthy and happy!
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Hadhazy, Adam. (2010). Think Twice: How the Gut’s ‘Second Brain’ Influences Mood and Well-Being. Scientific American. Web. 27 November 2015.
Magnusson, K.R., Hauck, L., Jeffrey, B.M., Elias, V., Humphrey, A., Nath, R., Perrone, A., Bermudez, L.E. (2015). Relationships between diet-related changes in the gut microbiome and cognitive flexibility. Neuroscience. 128-140.
Paddock, Catherine. (2015). Gut Microbes Important for Serotonin Production. Medical News Today. Web. 27 November 2015.
Perlmutter, David. (2015). “Healthy Gut Healthy Brain.” Experience Life. 54-59. Print.
About the author
Julie Smith is part also part of Baylor Scott & White Health’s integrative medicine program as a nutrition counselor. She is a registered and licensed dietitian who takes a functional and holistic approach to nutrition. Julie has been part of Baylor Scott & White since her undergraduate days at Baylor University where she received a Bachelor’s of Science in Nutrition Science in May 2011, followed by her dietetic internship at Baylor University Medical Center at Dallas, which lead into her current full-time position.