The Brain is Connected to the …What? Yes. The Intestines!

Have you ever been so stressed that you got a stomachache? Have you ever noticed a mood change (a little anxious, or a little down) after a course of strong antibiotics? Has your fear ever made you lose your appetite?

As much as we know about the brain, we are barely scratching the surface of all its functionality. The same is true of our digestive system. Although practitioners for many years have observed that poor gut health can impact brain activity and vice versa (think anxiety and diarrhea for one), they had no idea how close they were to discovering a new systemโ€”the gut-brain axis. It turns out that there are more similarities in the compounds found in both our brains and intestines than we might ever have imagined. And the interconnections are myriad.

Researchers define the gut-brain axis (GBA) as consisting of bidirectional communication between the central and the enteric nervous system, linking emotional and cognitive centers of the brain with peripheral intestinal functions.

Put in other words, what happens in the brain impacts the gut and vice versa. This is good news as improving the health of one system improves the other as well.

The Microbiome

One of the biggest features of the GBA is the healthy bacteria living in the intestines. The first year of life is a foundational period for the development and diversity of these bacteria and the gut microbiome. Subsequently, the gut microbiome will influence the brain and cognitive functioning. That is why babies that are born via Caesarean section are now inoculated with the motherโ€™s natural bacteria that normally would have happened via a vaginal delivery. In fact, in a study involving 89 infants, researchers were able to conclude that microbial composition at 1 year of age correlated with cognitive abilities at 2 years of age.

In a randomized, double-blind, placebo-controlled trial, women in their second trimester of pregnancy were given Lactobacillus rhamnosus daily until six months postpartum, if breastfeeding. The women receiving the probiotic had significantly lower postpartum depression and anxiety scores compared to the placebo group.

Neurotransmitters are nervous system chemicals that impact everything from how our brain works, mood, energy, and even how our body functions in general. The gut microbiome is highly involved in the regulation of neurotransmitters, including synthesis, release, and reuptake of glutamate, acetylcholine, dopamine, serotonin and gamma-aminobutyric acid (GABA). Alterations in these neurotransmitters are indicated in conditions like Alzheimerโ€™s disease, Parkinsonโ€™s disease, autism spectrum disorders, schizophrenia, anxiety and depression.

For example, Lactobacillus plantarum produces acetylcholine and Bifidobacterium can synthesize GABA. Research has demonstrated that germ-free mice have significant disruptions in their serum levels of GABA, serotonin, acetylcholine, along with their precursors. One study found that when fecal samples from children with autism were transplanted into rats there was a subsequent decrease in GABA and norepinephrine levels.

Vitamin D

Medical research has found that there is a growing body of evidence for the effects of vitamin D on intestinal host-microbiome interactions related to gut dysbiosis and bowel inflammation. Scientists have reported that vitamin D and its receptor regulate intestinal barrier integrity, and control various aspects of immunity in the gut. Metabolites from the gut microbiota (healthy bacteria) may also regulate expression of the receptor, while vitamin D may influence the gut microbiota and exert anti-inflammatory and immune-modulating benefits. The underlying mechanism of vitamin D in bowel diseases is not fully understood, but maintaining an optimal vitamin D status appears to be beneficial for gut health. And as we have learned, improving gut health is crucial to brain function.

A clinical trial involving vitamin D supplementation and probiotics had positive results in people with chronic schizophrenia. Participants received 50,000 IU of vitamin D3 every two weeks and 8 billion colony forming units (CFUs) of Bifidobacterium bifidum and several Lactobacillus spp. After 12 weeks, significant improvements were noted on the general and total Positive and Negative Syndrome Scale (PANSS) scores. Plus, improvements in total antioxidant capacity, and reductions in malondialdehyde and c-reactive protein levels. C-reactive protein is a stellar indicator of systemic inflammation.


Curcumin is a polyphenol found in the spice, turmeric. However, turmeric has very little curcuminโ€”as little as 2 percent. Therefore, the medical research has centered on the use of curcumin, extracted and concentrated. Curcumin has been demonstrated in clinical research to ameliorate inflammation and gastrointestinal symptoms caused by inflammatory bowel diseases (IBD). Newer insights have also found that curcumin may exert some of its benefits through the GBA. In an animal model, treatment with curcumin was found to decrease anxiety-like behaviors through its beneficial effects of microbial community composition, shifting microbial metabolite profiles, and reducing gastrointestinal inflammation.

In an animal model of colon cancer, treatment with curcumin plus turmeric essential oil (BCM-95 Curcumin) and vitamin E isomers were found to inhibit colon cancer cell proliferation along with improving microbial diversity. After 34 days of treatment, there was a 44 percent increase in microbial diversity versus the untreated control group. Additionally, in the curcumin group, there was a significant increase in Lactobacilla and Bifidobacteria species by 20-fold and sixfold, respectively, that occurred naturally in the gut with ongoing curcumin exposure. The finding that curcumin encourages the proliferation of some of the healthy probiotics in our microbiome is incredibly important.

Greek Mountain Tea

Greek mountain tea (Sideritis scardica) is an herb from the Mediterranean region that has been used for centuries as a tonic for energy, stress reduction, focus and stamina. Though used as a tea, it does not contain caffeine. Shepherds used to gather it while watching their flocks to make tea, hence its folk name, Shepherdโ€™s Tea. While the tea is a healthy food, research has been focused on using the herb in supplement form as a more concentrated extract.

Modern research has confirmed that Greek mountain tea has cognitive enhancing properties that are likely the result of multiple mechanisms of action. Some of the key constituents in Greek mountain tea include polyphenols that are able to protect the gastrointestinal tract and mucosa from oxidate stress and damage. Other research has found that this herb can increase blood flow in the brain, which results in downstream effects like reducing anxiety, improving thinking and problem solving and overall neuroprotection.


The enteric nervous system (ENS) is an extensive network of ganglion-rich nerve connections. The human ENS contains approximately 400-600 million neurons and is the largest and most complex aspect of the peripheral nervous system. The peripheral nervous system is the nervous system that is not located in our brain or spinal cord. The ENS is located within the walls of the GI (gastrointesitnal) tract, extending all the way from the esophagus to the anal canal.

Certain kinds of oxidative stress can cause great damage to the nervous system regardless of location. Doctors have known for many years that there are nervous system illnesses that affect both brain and gut in an interconnected manner. For example, in Parkinsonโ€™s disease, there may be gastrointestinal symptoms, like constipation, as early as 20 years before motor symptoms arise. Proinflammatory cytokines like IL-1, IL-6 and TNF-alpha can damage the GI tract and over time, cause damage to the enteric neurons and eventually the dopaminergic neurons. This reduces the amount of dopamine that can be made. Low levels of dopamine are a hallmark of Parkinsonโ€™s and are a cause of movement abnormalities.

One of the primary antioxidants throughout the body, whether in the gastrointestinal tract or central nervous system, is glutathione. When high levels of oxidative stress are present in the substantia nigra, one of the primary regions of the brain implicated in Parkinsonโ€™s, leading to lower concentrations of glutathione, the death of the neuron often follows. These reactive oxygen species can also damage the enteric nervous system and contribute to further disruptions in dopamine synthesis.

Glutathione comes in two forms. The first is active, a very powerful antioxidant, and ready to get to work. Scientists call this the reduced form. The second is inactive, no longer powerful, all used up and needs to be re-energized to provide any benefits. This is called the oxidized form. It is important to supplement only with active glutathione, but there are challenges. When used in clinics and hospitals, glutathione may be given intravenously (IV) which is highly effective. However, it is expensive, invasive, and some people do not have easy access to these kinds of treatments. Oral glutathione is problematic because the act of absorption in the intestines always converts the active to the inactive form of glutathione, even if it is enteric coated. An interesting technology from France has produced a glutathione that is sublingual, meaning it absorbs in the mouth, bypassing the digestion which could damage it. It is formulated into a soluble tablet that also incorporates key actives from pomegranate to keep the glutathione stable prior to use and as it dissolves. This form has been shown in human published studies to raise the active form of glutathione in the body after only 11 days of use and shifts the ratio of active to inactive in a positive direction by 230 percent.


The next time you are concerned about a gut problem, also consider your brain and nervous system. The same is true also of the brain and nervous systemโ€”if there are issues, consider also gut function. The food we eat and the supplements we take can play a powerful role in how these systems interact.VR


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Cheryl Myers is an integrative health nurse, author, and an expert on natural medicine. She is a nationally recognized speaker who has been interviewed by the New York Times, Wall Street Journal and Prevention magazine. Her many articles have been published in such diverse journals as Aesthetic Surgery Journal and Nutrition in Complementary Care, and her research on botanicals has been presented at the American College of Obstetrics and Gynecology and the North American Menopause Society. Myers is the head of scientific affairs and education for EuroPharma, Inc.

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