Critical Aspects of Health: The Gastrointestinal Tract

The Gastrointestinal Tract

Over the coming months, we are exploring in detail various bodily systems and nutritional solutions for the optimal functioning of these systems. Previously, we explored the immune system and male and female reproductive systems. This month, we will discuss the gastrointestinal tract.

Other recent articles in this newsletter have discussed in depth the health of the gallbladder, liver and pancreas. Therefore, this article will only briefly touch upon those three organs and revolve primarily around the gastrointestinal tract, a summary of the way it works, how it plays a crucial role in immune health and the secretion of serotonin, and factors affecting the health of this vital system.

The GI Tract: Reviewing Its Function

The gastrointestinal tract generally refers to a continuous structure that begins with the mouth, followed by the stomach, the intestines and ends with the anus. The “digestive system” has a broader definition that also encompasses the gallbladder, liver and pancreas.

The entire length of the gastrointestinal tract is between 18 to 30 feet long. Approximately 90 percent of digestion (and essentially all lipid digestion) takes place in the first two sections of the small intestine (duodenum and jejunum).

The esophagus, stomach and duodenum (the first segment of the small intestine) are considered to be the upper gastrointestinal tract, although sometimes the mouth and pharynx are included. The lower gastrointestinal tract includes most of the small intestine and all of the large intestine and according to some references, includes the anus, as well.

Digestion begins with the cephalic phase reflex, when the oral cavity is stimulated by the smell, sight and taste of food. This immediately elicits salivation, gastric acid secretion and pancreatic and endocrine secretions. These responses serve to prepare the alimentary canal for digestion, transport and use of ingested nutrients.

Once food enters the mouth, the process of chewing initiates the breakdown of food. It also stimulates the flow of saliva, which is rich in amylase, an enzyme that begins the breakdown of starches into sugars. When food enters the stomach, gastrin increases the release of stomach acid. Gastrin is also necessary for normal cell growth in the lining of the stomach, small intestine and colon.

Next, the I-cells in the mucosal epithelium of the small intestine synthesize cholecystokinin (previously called pancreozymin), a hormone involved in the digestion of fat and protein. When cholecystokinin is secreted in the duodenum, it triggers the release of digestive enzymes and bile from the pancreas and gallbladder. It also acts as a hunger suppressant.1

As food travels down the gastrointestinal tract, it is progressively broken down into fundamental particles—amino acids, glucose, vitamins and minerals. These nutrients are actively or passively absorbed through the intestinal wall and into the bloodstream to provide specific nutrients and energy to the body’s cells.

Tight Junctions and Leaky Gut

In order to ensure colon health, it is important that the tight junctions (and other types of cell junctions including Desmosomes) are working properly. The tight junction spaces between cells that line the intestines are normally sealed. However, when the intestinal lining becomes irritated or is affected by an unbalanced inflammatory response, the junctions loosen and allow molecules, which are larger than those normally permitted, to pass from the intestines into the blood. This can trigger cellular injury and immune system reactions since these large molecules are perceived as foreign. Much like the initial crack in a large dam, without immediate repair, progressive “cracking” occurs to the intestinal lining, eventually allowing misplaced flora, undigested food particles and unwanted by-products to pass into the blood.

Disturbance of the tight junctions contributes to increased intestinal permeability or leaky gut syndrome (LGS). The intensity of the symptoms that can arise varies depending on the effect on the intestinal natural defenses. Individuals with LGS can experience one or more of these symptoms: abdominal discomfort, nervousness, suboptimal respiratory health, joint and muscle aches, confusion, occasional fuzzy or foggy thinking, gas, everyday indigestion, changes in mood, suboptimal immune health, skin rashes, diarrhea, less than optimal memory, occasional constipation, bloating, fatigue and feeling hung-over.

Immune System Central

The gastrointestinal tract’s role expands far beyond being responsible for the entry of nutrients into the body. It also is responsible for triggering the primary immune response to orally ingested particles. This is because the gut-associated lymphoid tissue (GALT) contains 70 percent of the body’s immune cells, spread along the intestine in Peyer’s patches and the lamina propria.2-3

GALT consists of isolated or aggregated lymphoid follicles that form Peyer’s patches. By their ability to transport antigens and bacteria, Peyer’s patches are the intestine’s immune sensors.2 (Some gastrointestinal symptoms have been associated with suboptimal function of the Peyer’s patches.)3

It is in this way, that specific nutrients or their combinations, as well as the microflora (healthy bacteria colonizing your gut environment), are capable of modulating the immune system through cell activation, production of signaling molecules or gene expression. In fact, after mice were fed diets high in fats or carbohydrates, researchers noted that there was an increase in T-cells and a decrease in B-cells from Peyer’s patches.2 The number, size and T-cell composition of Peyer’s patches are influenced by the gut microflora.

Serotonin Production

Serotonin (5-Hydroxytryptamine or 5-HT), despite the fact it is often called a “feel-good hormone,” is actually not a hormone at all but rather an important neurotransmitter within the brain and the gastrointestinal tract. In the GI tract, serotonin influences intestinal movement (motility). The Enterochromaffin (EC) cells in the intestines produce approximately 80 percent of the human body’s total serotonin. These cells release serotonin in response to food in the lumen, which causes the gut to contract around the food. If irritants are present in the food, the EC cells release more serotonin, which accelerates intestinal movement, causing diarrhea, as a way to ensure that the gut is emptied of the irritating substance. If levels of serotonin rise in the blood faster than the platelets can absorb it, the level of free serotonin in the blood is increased. This activates 5HT3 receptors in the chemoreceptor trigger zone, which in turn stimulates vomiting.4

The important influence of this neurotransmitter on the GI tract led one group of researchers to conclude, “Serotonin as a neurotransmitter and gastrointestinal hormone appears to be a key to understanding a number of symptoms of gastrointestinal disorders like nausea, vomiting, pain, diarrhea and constipation.”5

Another Important Factor

A discussion of the gastrointestinal tract would not be complete without addressing an imbalance of intestinal bacteria. The GI tract is vulnerable to bacteria originating from anything ingested; such imbalances can affect the stomach or the first part of the small intestine in about half the world’s population.6 The effects of these bacteria can go unnoticed in some people, while in others it can lead to poor stomach health.

TABLE 1. Potential Symptoms of Bacterial Imbalance in the GI Tract6-9
A ache or burning discomfort in the abdomen

Other areas of wellness that this bacterial imbalance can impact include cognition, heart health and certain aspects of eye and skin health.10-17

The spread of these types of bacteria can be attributed to contact with saliva or fecal matter or from contact with meat and seafood.18 Although stomach acid is the body’s natural way to keep the growth of these bacteria in check, it is not always completely effective.6 A need to rebalance GI tract health can occur because of an imbalance in the colonization of flora in the mouth.19

Achieving healthy balanced flora in the GI tract is important in order to keep the mucosa of the stomach and intestines in optimal health in both the short term and the long term.20

Strengthening the GI Tract

A number of supplements can be used to support the health of the GI tract. Probiotics, such as those found in BioPRO™, can provide a foundation of optimal intestinal health and encourage peak immune function. Within a healthy intestinal tract, there is a balance between the good and bad bacteria. Dysbiosis—when this delicate balance is disrupted and the bad bacteria begin to win out over the good bacteria—has been shown to occur in people with an irritated lower GI tract. Probiotics can support the health of people with gut microbiota imbalances and altered wall permeability.21 Researchers also have found that probiotic formulations can support the colonization of beneficial flora and support against bacterial imbalances impacting stomach health.21

Mastic gum (as found in CeaseFire®) also can help keep the GI tract healthy in cases of unwanted bacterial growth in the stomach. Studies indicate that mastic gum can effectively support gastrointestinal health in a concentration-dependent manner.22 One clinical trial tested the efficacy of mastic gum supplementation in patients with occasional indigestion and stomach discomfort. The results showed that in the subjects receiving mastic gum for 3 weeks, 77 percent reported significant improvement compared to only 40 percent in the placebo group.23

Other natural substances found in GI Cell Support can be used to provide a foundational balance of optimal wellness in the GI tract and to improve the functioning of the tight junctions, thus enhancing the integrity of the intestinal walls and reducing intestinal permeability. Glutamine is essential for maintaining intestinal structure24 and serves as metabolic fuel for enterocytes that line the colon and affect cell proliferation.25 Deglycyrrhizinated licorice (DGL) supports gastric and duodenal health.26-27 N-acetyl glucosamine is deficient in people with suboptimal gastrointestinal health, possibly because it affects the synthesis of the gastric and intestinal mucosa’s protective glycoprotein cover.28 Other nutrients that can promote colon health are marshmallow,29-30 Berberine,31-32 Cabbage,33 Slippery Elm,29,34-35 Phosphatidylcholine36 and Gamma Oryzanol.37

In order to improve nutrient absorption from food and supplements, it’s helpful to add digestive enzymes into a GI-health regimen. Deficiencies of digestive enzymes—amylase, lactase, lipase, cellulase and neutral protease—can affect the digestive tract, causing bloating, flatulence and gastrointestinal discomfort from time to time. Without proper supplies of these enzymes, the body cannot efficiently digest the high-fat or high-starch meals.38-43 Vegetarian enzymes (provided in a vegetarian capsule) are generally better tolerated than animal-source enzymes, and they work over a broader pH range in the intestinal tract.

Activation of digestive enzymes and absorption of nutrients relies on an acidic pH in the stomach. Low stomach acid also increases vulnerability to imbalances in healthy flora. GastricAid® contains an effective level of HCL bound to betaine, which supports bile-release, methylation and detoxification. Pepsin is added to further support protein digestion, while B1, B6 and zinc support HCL production. Vitamin U (the active ingredient in cabbage) and Gamma oryzanol nurture the stomach mucosa. Fucoidan can prevent unwanted factors from adhering to the stomach cells and inhibits colonization by other microorganisms.44


The gastrointestinal tract is responsible for the absorption of nutrients our body needs to survive and is therefore a critical aspect of health. It also helps regulate immune function and produces the majority of serotonin in the body. A combination of probiotics and other natural substances can support the GI tract and lay a foundation for optimal health.

by VRP Staff


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