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Gut Health's Impact on Mental Health

Should I Get Screened for Colon Cancer?

As technology grows, more evidence is found that shows the influence of the human gut on mental health. As integrative medicine practitioners who focus on the whole human (holistic health), we understand the effect of diet on various symptoms, including some profound changes to mental health.

What we eat (and what eats the leftovers in our guts) can significantly impact the mind and emotions. Unfortunately, many people do not realize the impact of gut health on mental and emotional health. That is why, at Temecula Center for Integrative Medicine, we help patients improve their diets so they can improve their overall health. When emotions even out and mental clarity returns, the results are nothing short of miraculous.

Consider this fictitious patient, a composite character representing the mix of many patients of different races, ages, and genders who experience roughly the same symptoms.

Patient's Description of Symptoms:

  • Spiraling anxiety that starts with feelings of insecurity and vulnerability

  • Bouts of severe, almost crippling doubt about things that were previously no problem

  • Racing thoughts, racing heartbeat, panic attacks, sweating

  • Quick and exaggerated emotional responses (extreme anger, deep and prolonged crying, instant states of significant fear)

  • Depression, loss of hope

  • Decreased libido

  • Altered appetite with extreme cravings for sugar, salt, caffeine & alcohol

  • Inability to "think straight," focus attention, or remember events

As they experience emotional and cognitive issues, many of the patients represented in this scenario have been to numerous doctors, psychologists, and psychiatrists with little or no resolution to their underlying issues.

Interestingly, diet and lifestyle changes could help many of these patients eliminate the severe cravings and the episodes of doubt and agitation, lose weight, settle their stomach, enjoy even energy with an increased ability to focus, and greatly reduce or even eliminate deep depression and emotional swings.


Please consider that some people cannot reduce symptoms of disrupted mental health without medications and guidance from a psychiatrist, and one should never stop taking these medicines without medical supervision. However, if the situation is mild, it is worth addressing mental health through the diet before going on medications for mental health to see if symptoms resolve. For some, psychiatric medications are vital to maintaining good mental health. Yet, people currently taking such medications can also benefit from an improved diet. It's essential to work closely with your doctors so that psychiatric medication dosages can be reduced or adjusted as symptoms resolve.

The Gut- A Review of the Players

The human gut is part of the long tube where food enters the body and exits the body. This tube, called the gastrointestinal (GI) tract, allows food to be fed into the entry at the mouth, breaks down the food, has specialized areas to extract water and nutrition from the food, and then expels the remainder.

The stomach, with its acids, starts the breakdown of food into its smallest parts, with more breakdown occurring in the small intestine. Much of the work happens in the small intestine, where food molecules are pulled across highly specialized tissues into the body's interior. Note that the word "gut" is often used to refer to the whole GI tract or to any of the organs of the GI tract (stomach or large and small intestines).

The GI tract is a barrier from the "outside" world of food (and the microorganisms riding on food - bacteria, viruses, and fungi). This barrier allows the body to "decide" what food molecules get taken into the bloodstream. This barrier is also the juncture where the immune system kicks in to defend against microorganisms on or in the food.

The Microbiota

What the body does not take in from the GI tube passes through to the large intestine, where vast numbers of bacteria and other microbes live and feed on the leftovers. This guest list of microorganisms living in the large intestine is called the microbiota or microbiome. Microbiota are being studied intensely with new technology, and it is now known that they play a significant role in human health.

The Microbiota-Gut-Brain Axis: A Link Between Gut Health & Mental Health

Interestingly, microbes in the large intestine create a lot of chemical byproducts as they feed off the molecules of food that do not make it into the body's interior. As they further digest food molecules, gut microbes produce chemicals such as short-chain fatty acids (SCFAs), hormones, and chemicals used in the brain for communication (neurotransmitter substances). All of these substances influence the brain and, potentially, mental health! Researchers also found that the gut has a mesh-like network that forms a feedback loop with the brain. This circuit of influence, called the microbiota-gut-brain (MGB) axis, has been proven to have two-way communication with the brain (1).

Let's look closer at gut and mental health to understand their interactions better. Interestingly, both the gut and the brain have barriers that can erode, allowing substances to cross membranes that, in ordinary circumstances, would be prevented.

What is Gut Health?

The gut helps us take elements of nourishment and hydration into our bodies that feed and maintain our cells. Without nourishment and hydration, the human body dies. While taking in food, the gut also helps protect our bodies from things in or on the food, such as dangerous (pathogenic) bacteria or toxins such as lead or mercury.

Gut studies converge on a handful of criteria for health. The gut barrier must be intact, providing resistance to potentially harmful substances. Even large undigested food molecules can be detrimental if they get past the gut barrier because they trigger the immune system (usually resulting in inflammation). Where inflammation is fleeting or rare (not chronic), the gut performs its functions better, and the barrier is more likely to remain intact. Gut health is also associated with many different families of bacteria and healthy numbers of those bacterial families. Having good numbers of beneficial bacteria in the gut results in healthy levels of byproducts that influence brain chemistry, such as serotonin. Lastly, the cells that make up the gut must be nourished and protected from toxins to operate optimally. 

What is Mental Health?

Mental health is a general term that considers a person's sense of well-being expressed as outward actions, emotions, and thoughts (5). These elements, in turn, affect the ability to make effective decisions, hold a job, deal with stress, and enjoy relationships with others. If brain function is compromised, it might result in neuropsychiatric disorders, expressed as abnormal emotions, behavior, or thoughts. Some of the most widely experienced neuropsychiatric disorders are depression, anxiety, bipolar disorder, schizophrenia, and Alzheimer's Disease (6). 

Like the gut, the brain also has a barrier called the blood-brain barrier (BBB), which can become compromised. The same things that erode the GI tract membranes also deteriorate the BBB, allowing substances into the brain's interior that are normally prevented from entering. For example, if the BBB is leaky, bacteria, viruses, and toxins (such as mercury or lead) can enter the brain. However, there is great hope - the same things that repair the gut barrier can also help restore the BBB!

For good brain health (and thus mental health), neurotransmitter substances (chemical messengers) and hormones must achieve a balance in the brain that works for that person. The neurotransmitter substances gamma-aminobutyric acid (GABA), serotonin, dopamine, norepinephrine, and acetylcholine all help regulate aspects of mental health such as motivation, mood, and the evenness of emotions (2). Issues with the relative levels of these neurotransmitters can significantly contribute to mental health disorders. Even the overproduction of thyroid hormones and the stress hormone cortisol can disrupt the brain's delicate balance.

While brief inflammation is a healthy part of healing, chronic inflammation can be a driver of severe health conditions. Inflammation is one of the things that can help erode the BBB (3), so it should be controlled.

Lastly, some foods and chemicals enable the brain to produce new brain cells, manage connections of brain cells, and prevent plaque build-up, while toxic substances can do the opposite. Brain cells must be protected from toxins (by the BBB) and appropriately nourished.

Concepts to Master Brain & Gut Health

If a person experiences the symptoms mentioned at the beginning of the article and addresses just the items below, there is a good chance that many of the symptoms will be reduced or disappear. Implementing the Five Pillars of Health (discussed in a previous article) will also produce great improvement in both gut and mental health. 

1. Eating a Healthy Diet - Improving the diet can increase the functioning and stability of the gut by increasing the number and types of bacteria families. The human body and the microbiota need nutrient-dense raw materials, so reducing or eliminating artificial and highly processed foods while increasing whole foods will help the body function optimally. 

Many people are sensitive to the chemicals in foods, such as those used to preserve foods, and especially additives that "enhance" flavor or color. Paring down the diet to organic and hormone-free meats and whole foods (vegetables, nuts, seeds, and fruits) is a fast way to eliminate possible contributors to attention and memory issues, as well as panic attacks and racing heartbeat. Eating foods that counter, rather than provoke inflammation, increases gut and brain health. Simply put, the emphasis is on consuming an anti-inflammatory, nutrient-dense, whole-food diet.

Here are some practical steps to take. However, it may be easier to make long-term changes if you implement a few changes at a time rather than try to implement sweeping changes all at once. Our team is here to help you create and implement a plan that you can live with long-term.


  • Whole foods - Foods in their natural state are "whole foods." For example, instead of apple sauce, eat the apple. 

  • Fermented foods - Foods that have undergone the fermentation process provide high numbers of Lactobacillus and Bifidobacterium, which are associated with a healthy gut and increased brain health (4). Two easy fermented items to add to the diet are sauerkraut (found in the refrigerated section) and yogurt. Labels for the items should say they have live probiotics, bacteria, or enzymes and low amounts of added sugar.

  • Fiber - Also called prebiotics, fiber provides raw materials for the microbiota to digest, creating short-chain fatty acids (SCFAs) as a byproduct. SCFAs counter BBB-eroding inflammation, acting as a neuroprotective agent. SCFAs may also cross the BBB, positively influencing moods, memory, hunger levels, reactions to stress, and how well the body derives energy from foods. Good sources of fiber known as resistant starches are in whole grains (such as brown rice), greenish (unripe) bananas, and potatoes that have been cooked, cooled, and then re-warmed. Onions, garlic, and asparagus have inulin fiber. The pectin fiber in apples is a great producer of SCFAs. 

  • Foods high in Omega 3s - Omega 3s are fats that benefit the heart and the brain and are present in foods like salmon, herring, and anchovies. Chia, flax, and hemp seeds are good vegetarian sources of Omega 3s. Omega 3s reduce inflammation, including inflammation in the brain. Reducing brain inflammation can positively affect mental health. Many people with ADD or ADHD report feelings of calm when consuming high doses (1g-3g daily) of Omega 3s. Because Omega 3s reduce inflammation, they often reduce joint pain.

Remove or reduce: 

  • Foods or drinks with artificial colors, flavors, and preservatives - These can cause headaches, spikes in ADD/ADHD symptoms, and issues related to memory.

  • Alcohol, soft drinks, fruit juices - These high-sugar drinks can increase yeasts in the gut, which can overgrow and severely disrupt gut bacteria levels.

  • High-sugar foods - Sugar is a gut disrupter and provides an environment that invites chronic conditions such as diabetes, yeast overgrowth, and other illnesses.

  • Items made with seed oils - Seed oils (corn, canola, soybean, safflower oils) contribute to chronic inflammation, which in turn can drive arthritis, stroke, and diabetes (5).

2. Achieving Efficient Digestion - There's more to the equation than just the diet, as even the best diet in the world will only help human health if it is broken down and absorbed properly. Poor digestion and leaky barriers need to be addressed.

Many people do not realize they are not digesting their foods properly due to weak or inadequate amounts of stomach acid. Unfortunately, the symptoms of weak stomach acids are the same as an overly acidic stomach: acid reflux (6). Some people may reach for acid-reducers, further weakening their stomach acid. With strong acids, foods can be broken down adequately, especially protein and vitamin B12 (6). (Lack of iron and low vitamin B12 in blood tests can strongly suggest that digestion is compromised.) Digestive enzymes and HCl (a chemical akin to stomach acid) can be supplemented to aid digestion. Apple cider vinegar, diluted and taken with meals, can also assist with nutrient absorption.

3. Sealing Leaky Barriers - As mentioned previously, both the brain and the gut have membranes that protect them. If chronic inflammation causes the gut barrier or the BBB to erode, harmful substances can cross these protective barriers. When these barriers are breached, it is called "increased permeability," meaning its ability to restrict access is compromised. This can be expressed in the gut as Celiac disease and inflammatory bowel disease (7). Reducing chronic inflammation through an anti-inflammatory diet and supplements gives the membranes time to heal. The toxin glyphosate (an ingredient of weed killer) is present in high concentrations in wheat products such as flour and is known to erode the "tight junction" gatekeepers of the BBB (8) as well as the gut barrier in mice (9, 10). So, removing wheat products can also help keep the two barriers intact. Eating fiber that increases SCFAs can help repair the BBB. Bone broth, gelatin, and collagen are also excellent substances for helping to repair gut linings.

In Conclusion

Maintaining gut health is crucial for mental health. If you are experiencing mood swings, anxiety, depression, or brain fog, it may be worth working with a skilled practitioner to see if your symptoms can be resolved. Focused testing can detect nutritional deficiencies and imbalances of hormones, brain chemicals, or gut bacteria, and an individualized treatment plan can then be created. A skilled doctor can help determine if manipulating the diet or adding nutritional supplements may help resolve symptoms or if a referral to a psychiatrist is recommended. We would be privileged to partner with you to help you improve your health.


Jonathan Vellinga, M.D.

Jonathan Vellinga, MD is an Internal Medicine practitioner with a broad interest in medicine. He graduated Summa cum laude from Weber State University in Clinical Laboratory Sciences and completed his medical degree from the Medical College of Wisconsin.​

Upon graduation from medical school, he completed his Internal Medicine residency at the University of Michigan. Dr. Vellinga is board-certified with the American Board of Internal Medicine and a member of the Institute for Functional Medicine.




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8. Martínez, A. M. R., & Al‐Ahmad, A. (2019). Effects of glyphosate and aminomethylphosphonic acid on an isogeneic model of the human blood-brain barrier. Toxicology Letters304, 39–49.

9. Walsh, L., Hill, C., & Ross, R. P. (2023). Impact of glyphosate (Roundup TM ) on the composition and functionality of the gut microbiome. Gut Microbes15(2).

10. Del Castilo I, Neumann AS, Lemos FS, De Bastiani MA, Oliveira FL, Zimmer ER, Rêgo AM, Hardoim CCP, Antunes LCM, Lara FA, Figueiredo CP, Clarke JR. Lifelong Exposure to a Low-Dose of the Glyphosate-Based Herbicide RoundUp® Causes Intestinal Damage, Gut Dysbiosis, and Behavioral Changes in Mice. Int J Mol Sci. 2022 May 17;23(10):5583. doi: 10.3390/ijms23105583. PMID: 35628394; PMCID: PMC9146949.


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