By Douglas Husbands, DC, CCN, ABAAHP

The complex mechanisms involved in the body’s recognition of nutrients versus non-nutrients is analogous to a symphony in which each instrument plays a key role. Without harmonious coordination of all components involved, there would be a cacophony of sound rather than a symphony. Similarly, the involvement of systems in the human organism working harmoniously is essential for proper digestion, absorption and assimilation of nutrients from foods. The key system for this function is the gut or gastrointestinal tract (GI tract).

In this paper, I will review GI tract function as it relates to food intolerances or food allergies, and provide some general guidelines for improving one’s gut function to tolerate, and even properly assimilate, nutrients from foods without having intolerances or allergies.

Parts of the GI Tract

Simply speaking, there are five major parts of the gut: 1. Mouth, salivary glands and esophagus; 2. Stomach, liver, gallbladder and pancreas; 3. Small intestine: duodenum, jejunum and ileum; 4. Large intestine or colon: ascending, transverse, descending, sigmoid; and 5. Rectum. The length of the GI tract is about 30 feet, and the surface area of the GI tract is about the size of two tennis courts. It should take between 18 to 36 hours for food to go the whole length of the GI tract. The entire GI tract is lined with mucous secreting cells to protect the mucous lining from mechanical or chemical damage from the roughly 25 tons of food the average person consumes over a lifetime. The lining of the GI tract must also have cells that rapidly replenish and repair for protection from harmful external organisms and toxins in the environment.

Functions of Different Parts of the GI Tract

In general, the function of the GI tract is digestion and absorption of nutrients, with elimination of waste products. Digestion is breaking down foods into their components, such as proteins into amino acids. Absorption or assimilation refers to transport of nutrients across the membranes in the GI tract and into the bloodstream and lymph system, where they are carried into the cells throughout the body. Elimination refers to removal of the waste products from metabolism of food.

The basic job of the mouth, salivary glands and esophagus is to break down foods into smaller pieces and initiate the digestive process and food delivery to the stomach. The stomach mixes food with stomach acid, called hydrochloric acid (HCL), to break up large food particles into smaller ones, and gastric digestive enzymes to break down proteins into amino acids. HCL also prepares food for delivery to the small intestine. Special cells in the stomach also need to work properly for vitamin B₁₂ absorption.¹ Stomach acid is needed to help close the lower esophageal sphincter, to prevent acid reflux and food allergies, and kill pathogens such as Helicobacter pylori (H. pylori), which has been identified as the causative agent of stomach ulcers and gastric carcinoma.^2,3

Particularly in the elderly, too little stomach acid, not too much, is often the cause of an acidic feeling in the stomach and indigestion.⁴ Gastrin is a hormone produced in the stomach that stimulates movement of food through the stomach. Chronic antacid use hinders both HCL and gastrin secretion, predisposing to low tissue amino acids (with immune system impairment and muscle tissue wasting), acid reflux, low vitamin B₁₂ (with elevated blood cholesterol and homocysteine levels), greater propensity of food and other allergies, and an increased chance of parasitic and bacterial infections.⁵

Liver bile is sent to the gallbladder and then to the duodenum. Bile’s function is that of a detergent. It breaks down fats into smaller particles with the help of pancreatic enzymes for absorption. Bile and pancreatic lipase are also important for absorption of the fat-soluble vitamins A, D, E and K.

The pancreas secretes protein, fat and carbohydrate digestive enzymes. The pathogens H. pylori and Giardia can cause spasm in the duodenum, shutting off the flow of pancreatic enzymes into the small intestine, resulting in enzyme deficiencies and subclinical pancreatitis. H. pylori, if left untreated, can cause stomach cancer.⁶

The small intestine is where much of digestion and absorption occurs. The lining of the small intestine has fingerlike protrusions called villi. Their purpose is to increase the surface area for better nutrient absorption. The small intestine contains beneficial bacteria (primarily the Lactobacillus strain) to assist nutrient breakdown, production of B vitamins and vitamin K, reduction of serum cholesterol, support of normal elimination, and prevention of infection by pathogens. Some cells of the small intestine also secrete immunoglobulins. Immunoglobulins are immune cells that help fight infections. Immunoglobulins are named by different classes with different functions. For instance, immunoglobulin A (IgA) is present in high amounts in the GI tract.

About 60 percent of the secretory immunoglobulin A (sIgA) in the body is made in the small intestinal cells.⁷ This is important because the gut requires good immune system function since it is constantly exposed to foods and other substances coming in from the outside. Parasitic infections are more likely to occur with inadequate beneficial bacteria and impaired sIgA in the small intestine.

The colon’s primary role is fermentation of carbohydrates (resistant starch) and absorption of water and electrolytes. Lack of fiber and beneficial bacteria can increase the time it takes to eliminate feces, thereby exposing the body to toxins in waste material. Lack of fiber also tends to increase pathogenic bacteria, increase toxicity in the entire body, and lead to colon cancer. Research has shown the stool pathogenic bacteria Proteus mirabilis is possibly implicated as a causative factor in rheumatoid arthritis.^8,9Klebsiella pneumoniae has been implicated in ankylosing spondylitis,^10,11 which leads to fusion of the spine with significant permanent impairment. Though not all studies consistently show these pathogens present in all cases of these disorders, the consideration of their presence in each case must be considered. Finally, the rectum functions as a temporary storage area for feces. It has muscular walls to facilitate the primary function of elimination of wastes.

A healthy GI tract also has trillions of beneficial microscopic bacterial species lining the entire gut. There are so many of these beneficial bacteria that their total weight, if somehow calculated, would be about six pounds. Within a healthy gut, there are about 400 microbial species.¹² These beneficial organisms initially get entrance into the intestines through the newborn’s mouth while passing through the mother’s birth canal. We are also inoculated with them through ingestion of foods such as yogurt and vegetables. These beneficial bacteria come in different strains, with names such as Lactobacillus acidophilus, L. rhamnosus, L. casei and various strains of Bifidobacteria. As a group they are termed probiotics when they come from an outside source. When they reside inside the gut, they are termed microflora. Each part of the GI tract contains different predominant strains of microflora. Probiotics and microflora have multiple functions:^13-17

They inoculate a newborn’s GI tract to provide immune system protection.
They prevent the overgrowth of yeast such as Candida.
They promote resistance to disease-causing bacteria and fungi by producing antimicrobial substances.
They inhibit disease-causing, antibiotic-resistant, bacteria-laden (biofilms) lining mucous membranes.
They produce enzymes that help with detoxification.
They produce some B vitamins and vitamin K.
They aid in both digestion and absorption of nutrients.
They combat diarrhea.
They assist in proper immune-system balance between innate and acquired immunity.
They have anti-cancer effects on various cells.
They help maintain the tight junction lining of the intestines.
They are involved in processes through a part of the nervous system that prevents depression.

From this list, we can see that whatever disrupts the balance of gut-beneficial bacteria will have profound effects on our gut health and overall health. Excess refined sugar alters the balance of beneficial bacteria, predisposing to yeast overgrowth and immune-system impairment. Many prescription and nonprescription medications disrupt the GI tract microflora, most notably antibiotics, antacids, anti-inflammatory medicines and corticosteroids.

“I Have a Gut Feeling”

The gut contains its own nervous system that can control GI functions independent of the brain if necessary. This is known as the enteric nervous system (ENS). Without going into great detail in this paper, the take-home point is that there is a great deal of cross-talk between the ENS and the brain.¹⁸ There is bi-directional communication between the brain and the gut. Research now confirms that a component of depression is in the gut, and a component of irritable bowel syndrome is in the brain. Nutrients or drugs that influence brain function will influence gut function, for better or worse, and vice versa.¹⁹

Healing an Unhealthy Gut

With so many important components and so many associations with so many diseases, what can be done to heal the GI tract, thereby helping many bodily processes? More importantly, how can the gut help resolve food intolerances and allergies? From a functional health perspective, we want to first assess exactly what condition the gut is in and how it’s affecting other systems. This is done using the tools of advanced functional laboratory tests. In the context of this article, I will not address that aspect, other than to say functional testing identifies the underlying causes of problems, not just the pathology. Functional laboratory testing is analogous to finding the detailed steps and plans of a terrorist’s next attempt before they’ve put any of the plans into motion. Also using this analogy, many conventional diagnostic lab tests are like finding the clues identifying that the damage was due to terrorists after the attack already occurred.

In the conventional medicine model, the clinician asks how to suppress a particular symptom, such as acidic symptoms, depression or high cholesterol. In the functional health care model, we consider the origins of the symptoms, the underlying cause(s), and what needs to be done to restore proper function and optimal health. Once this is resolved, symptom relief naturally occurs.

Relative to the GI tract, a functional medicine/health caretherapeutic approach has become known as the “4R Program”:

1. What may need removing? Are parasites present? Are there any pathogenic yeasts present such as Candida? Are there any foods that temporarily need to be eliminated, such as gluten-containing foods which can cause autoimmune responses? Are food sensitivities or food allergies present requiring temporary removal of offending foods from the diet?
2. What may need replacing to support healthy GI function? Is the stomach producing enough HCL? What about digestive enzymes? Are tissue stores of basic nutrients, like amino acids very depleted?
3. Does the gut need re-inoculation? Are the levels of beneficial bacteria present in the gut depleted? How long has it been depleted? How frequently has it been depleted by use of antibiotics, antacids, anti-inflammatory medicines or corticosteroids?
4. What is necessary to repair the mucosal lining of the GI tract? Are certain foods, such as high sugars, inhibiting repair processes? Is there impairment of nerve function affecting the ENS, requiring chiropractic, acupuncture, etc.? A variety of specific nutrients and supplements, properly dosed and timely given, are required for repair.

A Functional Health Care Approach

After reading through this paper, it should be clear how gut health is an absolutely essential component for resolving food allergies and for overall health. Helping the gut to be restored to good health is not something to be left to someone who is inexperienced in doing this, because of the multisystem relationships. Nevertheless, due to the multifactorial effects of probiotics, HCL, digestive enzymes, particular nutrients and botanicals, these substances, when used appropriately, can often greatly decrease food allergies. In short, a functional health care approach is essential for management and resolution of food allergies.