1 Free Article Remaining (through 12/13/18)

Today, it is estimated that one out of every five American adults suffers a mental-health condition (43.7 million Americans—more than the combined populations of New York and Florida), and the statistic only seems to be worsening. Additionally, from 2011 to 2014, rates of youth depression increased from 8.5 percent to 11.1 percent; many youth are unable to access adequate treatment.

The medical establishment blames brain-based imbalances for this epidemic. But could it instead be due to gut dysfunction?

Gut health is rapidly gaining recognition for its vital role in overall health, especially mental health. References to “gut feelings” and the sensations of “butterflies in one’s tummy” are more than just figures of speech; in fact, the gut has named the “second brain”, given that it can act independently from the central nervous system.

What Constitutes a Healthy Gut?

Gut health is largely determined by the mycobiome, the collection of bacteria (symbiotic and pathogenic) as well as fungi, that resides in the gut. The keys to optimal gut health include maintaining a healthy balance of “good” and “bad” bacteria and fungi in the gut, and ensuring a healthy, robust gut lining.

The Mycobiome

The term “mycobiome” was coined by an NIH-funded researcher, Dr. M. Mahmoud Ghannoum, when he discovered the significant relationship between bacteria and fungi and its effect on the balance of the body’s bacterial levels. Dr. Ghannoum noted that the popular concept of the “microbiome” focuses on the bacterial community, ignoring the body’s equally important fungal populations.3

Nearly 80 percent of the immune system is located in the gut, which is why any alterations in bacterial balance can lead to various health conditions. For instance, an overgrowth of pathogenic bacteria can cause gut dysbiosis, which can contribute to more serious conditions like inflammatory bowel diseases (e.g. Crohn’s disease, ulcerative colitis) as well as neurological problems (e.g. depression, anxiety, and autism). In fact, research suggests that the aforementioned ailments actually stem from insufficient diversity of gut organisms (which can arise when beneficial strains are crowded out by a pathogenic species).

Gut Lining

The gut lining is comprised of epithelial cells, bound together by tight junctions. Any impairment to these junctions leads to hyperpermeability in the gut lining (“leaky gut”), allowing undigested foods and toxins to seep into the bloodstream. This causes inflammation that may precipitate the development of conditions like asthma, allergies, eczema, or migraines, and autoimmune conditions like fibromyalgia, celiac disease, and rheumatoid arthritis.

Leaky gut may derive from the use of medications such as antibiotics, birth control, aspirin, and NSAIDs; diets high in processed foods (with artificial ingredients and hydrogenated oils, especially) and alcohol can also be factors. Maldigestion of grains and dairy has also been linked to leaky gut, so these foods are best avoided during the healing phase (with possible reintroduction once the gut has properly healed).

The “Second Brain”

The enteric nervous system, also known as the “second brain,” is responsible for controlling the entire GI tract and all steps in the digestive process. It is located in the tissues lining the digestive tract, including the esophagus, stomach, small intestine, and colon. It allows us to swallow, coordinates the release of digestive enzymes, and controls blood-flow to facilitate nutrient assimilation and waste elimination.

The enteric nervous system “speaks” to the brain via millions of neurons, and is in constant contact with the central nervous system. Indeed, the enteric nervous system contains as many neurons as the spinal cord! It, along with the sympathetic and parasympathetic nervous systems, makes up the autonomic nervous system. However, the enteric nervous system can also act independently, monitoring the entire digestive tract alone.

Neurological disorders like depression and anxiety were once thought to be triggered by digestive problems. However, the opposite is likely true; gut dysfunction may cause changes in mood and behavior, triggered by the enteric nervous system.

Roughly 30 to 40 percent of the American population suffers from digestive complaints, which may help explain the recent uptick in incidence of depression, anxiety, and other neurological disorders.

Happiness and Your Gut

The health of the gut has a profound impact on happiness and overall wellbeing. A recent study illuminates the influence of specific strains of bacteria on our behavior and emotions. Researchers compared gut flora between several cohorts of women and noticed significant variation in cognitive function and emotions like anxiety and irritability, correlating to differences in gut-bacteria composition. According to numerous other studies, animals that were exposed to stressors exhibited pronounced differentiation in gut bacteria.

Furthermore, roughly 95 percent of the body’s serotonin is produced in the gut, primarily the colon. Serotonin is the “feel-good” neurotransmitter known for regulating mood balance and promoting happiness. Deficiencies in serotonin levels have been linked to neurological disorders like depression.1

It is evident that any alterations to gut flora can lead to health complications and overall malaise, but what exactly causes changes in gut bacteria? There are many contributing factors; in fact, gut bacteria naturally undergo day-to-day fluctuations. However, the two primary inputs governing long-term gut makeup are chronic stress and diet.


The body’s immediate reaction to stress, whether physical or mental, is to release adrenaline to facilitate survival. For instance, if you are hiking and suddenly get chased by a bear, your body releases survival-mode hormones to help you run faster. Your heart rate spikes, your eyes widen, and your blood platelets become sticky to prevent excessive bleeding if you are wounded. Thankfully, our bodies know how to rebalance their fight-or-flight and rest-and-recovery systems post-threat. Once the stressful situation ends, the sympathetic response gives way to the parasympathetic, and we relax.

Complications arise during chronic stress, such as when you work in a stressful environment. Since your body cannot differentiate between a physical stressor (angry bear) and a mental stressor (your job), it always activates the same sympathetic response, leaving you in a continual state of increased inflammation.

Inflammation is your immune system’s natural response to toxins, infections, and stress. If inflammation is prolonged, the immune system weakens, leading to neurodegenerative diseases such as Alzheimer’s and Parkinson’s disease as well as neurological disorders like ADHD, autism, anxiety, and depression. Therefore, integrating stress-management practices into your daily routine is critical for gut health; adequate sleep, sunlight, time in nature, relaxation, and healthy social interaction are all anti-inflammatory.


One of the most critical factors in gut-health optimization is the food you eat. As Ann Wigmore so powerfully expressed, “The food you eat can be either the safest and most powerful form of medicine or the slowest form of poison.”

A study published in BMJ Open found that nearly 60 percent of Americans’ daily calorie consumption derived from processed food: nutrient-poor products containing flavors, colors, sweeteners and hydrogenated oils, emulsifiers, and other additives. An examination of the diets of people struggling with depression indicated severe nutrient depletion, especially of vitamins, minerals and omega-3 fatty acids.

Processed foods weaken the integrity of the gut, promoting numerous diseases like diabetes and autoimmune conditions. The best way to maintain a robust gut is to consume whole foods in their most natural, unprocessed state, including fruits, vegetables, humanely raised meats and seafood, and good-quality fats like grass-fed butter and coconut oil.

In light of the profound effect that the microbiome exerts on overall health, we can see that our mental health may rely even more heavily on gut function than on the brain’s state. By maintaining a nutritious diet that supports gut health while also managing stress levels, we can promote overall feelings of well-being and happiness.

  • Full of gut-healing nutrients like collagen and L-glutamine, bone broth is one of the best foods to support gut health; it is also a great source of protein.
  • Probiotics (beneficial bacteria) and fungi that line your gut are critical for optimal gut health; in studies, probiotic supplementation reduced feelings of depression and anxiety and improved overall well-being.
  • When you take probiotics, you must provide them with a healthy environment (including a food substrate); prebiotics (such as resistant starch) serve as this bacterial nourishment. Prebiotics have been linked to prevention of conditions as varied as colitis, cancer, obesity, and diabetes, as well as chronic constipation.
  • Fermented foods (e.g. sauerkraut and kimchi) are rich with diverse probiotic strains, and are an excellent dietary addition to maintain a healthy microbiome.
  • Cultured dairy (e.g. yogurt or kefir) is milk fermented with lactic acid bacteria. When homemade, it is much richer in probiotics than store-bought yogurt, given that homemade yogurt is cultured longer than most commercial yogurts. Plus, making your own homemade yogurt or kefir allows you to source dairy from grass-fed, humanely raised cows, as well as avoid refined sugar and other processed ingredients.
  • While coconut oil is an excellent source of healthy fats, it has incredible healing properties as well. Coconut oil is not only anti-inflammatory but also antimicrobial, which helps eradicate pathogenic bacteria lingering in the gut. Coconut oil also helps remove waste and toxins from the digestive tract that may contribute to digestive discomfort or even neurological complications like depression, brain fog, and anxiety.


1 http://www.mentalhealthamerica.net/issues/state-mental-health-america

2 ibid.

3 http://www.the-scientist.com/?articles.view/articleNo/45153/title/The-Mycobiome/

4 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2515351/

5 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4315779/

6 http://jn.nutrition.org/content/141/5/769.full

7 http://www.vivo.colostate.edu/hbooks/pathphys/digestion/basics/gi_nervous.html


9 http://www.hopkinsmedicine.org/health/healthy_aging/healthy_body/the-brain-gut-connection

10 http://www.hopkinsmedicine.org/health/healthy_aging/healthy_body/the-brain-gut-connection


12 http://www.sciencedirect.com/science/article/pii/S0889159110005295

13 https://www.scientificamerican.com/article/gut-second-brain/

14 https://www.medicalnewstoday.com/kc/serotonin-facts-232248


16 https://www.integrativepsychiatry.net/brain_inflammation.html

17 http://time.com/4252515/calories-processed-food/

18 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2738337/

19 http://www.medicalnewstoday.com/articles/304645.php

20 https://www.ncbi.nlm.nih.gov/pubmed/19338686

21 https://www.ncbi.nlm.nih.gov/pubmed/20974015

22 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3376865/