Gut Health, Immune System and the Brain

The concept of gut health has been gaining more and more interest in the past few years. It does not have a clear definition and can refer to various issues altering the function of the digestive tract, such as maldigestion of food, bowel irregularity, and inflammation of the gastrointestinal tract. It mostly refers to maintaining a good balance of the gut microbiome.

The gut microbiome is the foundation of our general health. About 200 species of bacteria, yeast, and even viruses, totaling 300 trillion microbes, live in the large intestine. Most of them are beneficial to our health, but some can become harmful, and any imbalance can impact our health at various levels. In this newsletter, we will examine the important role of the microbiome on our immune system and brain function.

We will explore the interconnection between the gut microbiome, metabolism, and weight in a future newsletter, as this is another complex topic.

Gut Health and the Immune System

Let’s start with the connection between gut health and the immune system. Seventy percent of our immune system cells reside in our gut. These tissues, where the immune cells are located throughout the intestine, are called GALT (gut-associated lymphoid tissue). Every day, these cells act as guardians of our body, filtering external aggressors and toxins, and preserving our general health from environmental threats.

Without delving into all the details, several studies have demonstrated that signals from the microbiome are critical not only for regulating the local immune system but also for profoundly influencing the general systemic immune responses in our body.

A healthy microbiome is essential for this immune system to function optimally. Any abnormality in the population of the gut microbiome, also called dysbiosis, can affect our immune defense and increase the risk of chronic infections, autoimmune diseases such as Hashimoto, inflammatory bowel disease, and even cancer.

Recent studies show that an imbalance in the gut microbiome can trigger a systemic inflammatory response, with consequences for the cardiovascular system, increasing the risk of atherosclerosis, heart attack, and stroke.

Gut Health and The Brain

A second important connection exists between the gut and the brain. The gut is often referred to as the “second brain of the body.” Any imbalance of the microbiota can influence our mood and cognitive function.

Research shows that 90% of the neurotransmitter serotonin is secreted in the gut by various bacteria or yeast, including Streptococcus, E. coli, Enterococcus, and Candida. When these bacteria are in good proportion in the gut, they are beneficial to our emotions and balanced mood. Other organisms, such as Bacillus and Saccharomyces, can produce neurotransmitters like norepinephrine and dopamine, which are involved in concentration and memory.

Some other bacteria regulate the production of GABA, an important neurotransmitter that regulates sleep and mood. A lack of certain bacteria in the microbiome can cause deficient production of GABA, increasing the risk of sleep issues and anxiety. This suggests that an imbalance of the gut microbiome can significantly impact the regulation of our neurotransmitters, consequently influencing our mental and emotional health.

What makes this even more complicated is that there is a bidirectional connection between the gut and the brain, primarily mediated by the parasympathetic nervous system, especially the Vagus nerve. Instead of getting into the complex systems involved in this regulation, we can summarize by saying that the Vagus nerve serves as the link between the gut microbiome and the brain. It senses various signals in the gut environment and transmits information to the neurons in the brain. It is also the most important pathway of the autonomic system (not under conscious control) in regulating gastrointestinal tract function. The Vagus nerve is associated with many neurodegenerative diseases such as Parkinson’s disease, Alzheimer’s, and ALS. A nervous component is almost always associated with conditions such as irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD).

It is therefore no accident that the interconnection between the Vagus nerve and the microbiome is implicated in these pathologies.

Testing for Gut Health

Given the importance of the microbiome on our general health, it is crucial to maintain a healthy intestinal flora as we age. One way to assess the microbiome is through a stool test. Several companies have developed various techniques based on genomic evaluation, some even incorporating artificial intelligence.

At VitaLifeMD, we recommend the Genova GI Effects Comprehensive Profile test, which provides a good insight into general gut function. Dr. Read is pleased to inform her patients that a new test can now be added to the original GI Effects kit: Microbiomix. This test may reveal treatable information not seen in the GI Effects test. It uses DNA whole genome sequencing to assess one’s complete gut microbiome and its potential function.

The Microbiomix platform detects bacteria, fungi, and parasites, amounting to over 28,000 species. Each person's microbiome contains over 200 species, all listed in the personalized report. The test assesses gas-producing organisms, including methane producers and hydrogen sulfide producers involved in SIBO. It can identify newly discovered species that may not be well known to science, and results can show how they may be contributing to overall health. The technology of the test is based on DNA analysis, whereas other microbiome tests on the market are RNA-based. DNA testing is more stable for the long-term evaluation of gut health, as RNA testing provides a snapshot in time and may not be indicative of the long-term microbiome status.

Microbiomix offers a simple way to evaluate the gut microbiome and is emerging as one of the best tests to identify potential health risks. It can help prevent future chronic diseases and promote optimal health.

Protecting our Gut Microbiome

Now that we understand the importance of the gut microbiome for our general health, what can we do to protect its integrity and swiftly restore any imbalance?

The good news, despite the complexity of microbiome function, is that we may be able to improve gut health by consuming foods that support these microorganisms.

Fibers should be present at an intake level of 20 to 40 grams daily. Insoluble fibers are essential to regulate bowel movements; soluble fibers form a gel in the lumen of the intestine and after fermentation with good bacteria, produce compounds called short-chain fatty acids that can protect the lining of the gut against harmful bacteria. Fibers are found in various types of food such as beans, lentils, whole grains, vegetables and fruits.  

Prebiotics are a specific kind of fiber that have a high propensity to be fermented by the good bacteria in our gut. This enhances the ability to protect our microbiome and eliminate potential pathogens. Prebiotics-rich foods include asparagus, artichokes, garlic, onions, bananas, almonds, oats, dandelion greens, leeks, and flax seeds.   

Probiotics are live microorganisms present in some foods that are part of our healthy microbiome. The most common are Lactobacillus and Bifidus bacteria. These bacteria present a variety of health benefits and need to be present in our food regularly. Not only do they contribute to increasing the population of good bacteria in our gut, but they benefit our immune system directly and protect against the invasion of harmful organisms.   Foods rich in probiotics include Greek yogurt or yogurts with live active cultures, kefir, kombucha, sauerkraut, kimchi, and fermented soybeans. 

Polyphenols are a type of natural nutrients found in plants, vegetables, and fruits. They are not digested in the stomach but transit directly to the colon where they are metabolized by microorganisms. They are potent antioxidant and anti-inflammatory agents and protect the body against the damage caused by free radicals and toxins. Foods rich in polyphenols include fruits (blueberries, strawberries, cherries, apples), vegetables (broccoli, cabbage, cauliflower, tomatoes) spices (turmeric, ginger) whole grains (wheat, oat, corn), green tea, and even coffee, dark chocolate, and good wine!  

Omega-3 fatty acids are often forgotten when it comes to gut health and yet are essential to reduce inflammation along the digestive tract. The polyunsaturated fatty acids can positively effect the microbiome by increasing the production of anti-inflammatory compounds such as short chains fatty acids. They also have a role in strengthening the integrity of the gut lining. Omega-3 are found in fish and seafood, and small amounts exist in nuts, flaxseeds, and chia seeds.  Some eggs are now enriched in Omega- 3 but not as much as oily fish or oysters. 

Besides eating good food, some supplements can improve gut health. These include quality brands of pre/probiotics, Omega-3, and fibers. Some patients will need additional support with digestive enzymes, and some other supplements including L-glutamine (an amino acid that protects the lining) or colostrum (rich in immunoglobulins for immune system support). 

Moreover, emerging literature highlights the benefits of neuromodulation for gut health, underscoring the role of neurotransmitters and the Vagus nerve in regulating digestive tract function. Ongoing studies explore the advantages of neuromodulation devices like Nurosym, available in Europe and potentially coming to the United States.

In the meantime, let’s prioritize nourishing foods and appropriate supplements for gut health. If you wish to discuss your personal needs, please call our office to schedule an appointment, and our staff will gladly assist you.