In Article 4, you learned about the differential diagnosis of enteropathy, shown in Figure 4.1.
In review, enteropathy refers to a triad of the most common gastrointestinal or “gut” symptoms:
- Abdominal pain and/or discomfort
- Gas (abdominal bloating, distention, flatulence, and/or gurgling-rumbling)
- Bowel dysfunction (diarrhea, constipation, or both)
Enteropathy has many potential underlying diagnoses, causes, and associated conditions. In this article, we focus on #6: Food, Maldigestion, & Malabsorption, including bile acid malabsorption (BAM). Later articles will cover Sucrose Intolerance, carbohydrate malabsorption of FODMAPs, and wheat/gluten malabsorption and intolerance, including celiac disease.
Enteropathy Symptoms Are Commonly Triggered by Eating
The majority of people suffering from enteropathy report that eating triggers symptoms between 30 minutes and 2 hours or so after eating, particularly the urgent need to have bowel movements, which are often loose. (Symptoms occurring within 30 minutes of eating, particularly if associated with nausea and vomiting, usually indicate a stomach problem rather than intestinal disorder.) Specific triggering foods may or may not be evident or identified. But first, let’s go over three short gut anatomy and physiology lessons to set the stage for your understanding the relationship of food with enteropathies.
Essentials of Gut Anatomy
Take a bite, and let’s follow the food through your gut. Refer to Figure 5.1.
The gut is a 30-foot-long tube.
The gut microbiome begins in the mouth. Digestion begins the moment calories are introduced here, even before they are swallowed. Food is broken down by chewing and by amylase in saliva, an enzyme that breaks down carbohydrates.
Once swallowed, food moves down the esophagus by muscle contractions (peristalsis).
Food is further broken down by mixing and grinding from strong peristalsis, along with pepsin and lipase activated by the acidic environment created by hydrochloric acid (HCI).
Further digestion and absorption begin in the duodenum, the first part of the small intestine, aided by acids in bile made in the liver and by enzymes from the pancreas (including amylase) and the intestinal lining. (The gall bladder, bile ducts, and pancreas are shown but not labeled.)
5. Small Intestine
Approximately 20 feet long, the small intestine is responsible for further digestion and absorption of nutrients, including vitamins, minerals, proteins, carbohydrates, and fats. The upper part is the jejunum. The lower part, the ileum, connects to the colon by the ileocecal valve in the right lower quadrant of the abdomen. This valve normally prevents backward flow of contents from the colon into the ileum.
From 4 to 5 feet long, the colon is horseshoe shaped. It solidifies the residual liquid and undigested contents passed from the ileum and stores it as stool or feces. Normally, strong peristaltic muscular contractions (high-amplitude propagating contractions) move the stool forward. The end of the colon, called the sigmoid, is located in the left lower quadrant.
The sigmoid becomes the rectum, which ends at the anus, through which stool or feces are eliminated by having a bowel movement (defecation).
The Essentials of Gut Physiology
Next, see what happens to the food you ate in the small intestine. Refer to Figure 5.2.
Enteropathy symptoms originate from the small intestine and colon, represented by two cylinders. The focus here is on the small intestine (red arrow) shown in a cut-away side view. The vertical brown lines represent the small intestinal wall.
Two completely different gut function phases controlled by the gut brain (Figures 2.1 and 2.2) are like computer programs.
1. Digestive (Fed)
This phase was described in Figure 5.1 and begins the moment anything of caloric content is taken into the mouth.
2. Fasting (Unfed)
This phase begins in the small intestine about 4 hours after eating. Here, between meals and over-night — no snacking allowed! — the migrating motor complex or MMC replaces digestive peristalsis. Like a broom, the MMC sweeps the liquid contents of the small intestine into the colon through the ileocecal valve every 90 to 120 minutes, lasting 5 to 8 minutes. This means that anything containing calories entering the mouth will shut the MMC down for 4 hours, even if not swallowed. Importantly, the MMC does not travel into the colon or cause a bowel movement. Anything that impairs the MMC or the cleaning flow in the small intestine can result in SIBO (small intestinal bacterial overgrowth).
Essentials of Microscopic Gut Physiology
In addition to nutrient absorption described in Figure 5.1, the small intestine also defends you from the environment, which you eat. It serves as a barrier. Impairment of the barrier is known as “leaky gut.” Refer to Figure 5.3.
Figure 5.3 is a microscopic side view of the small intestine. To orient you, the arrow on the left (1) points to the cells of the gut surface. Above the cell layer is “inside the gut tube” (2). Below the cell layer is “within the gut lining” (3).
1. Cells of the Gut Surface (Epithelium)
Note the cell layer is only one cell thick. Not shown are the mucus layer (biofilm) coating the surface and IgA, an immunoglobulin. The total surface area of the gut lining is approximately the size of a football field. Nutrient absorption primarily occurs across the cells.
2. Inside the Gut Tube (Lumen)
The sandwich represents digesting food, while the bacteria represent the gut microbiome.
3. Within the Gut Lining (Lamina Propria)
Left to right, seventy five percent of the immune system is located here, along with blood vessels and the little brain in the gut.
4. Spaces Between Cells (Tight Junctions)
These spaces between cells are dynamic and can loosen, resulting in “leaky gut.”
5. “Bad Guy” (Antigen)
The biohazard symbol inside the gut tube represents food components, additives, chemicals, and microbes, including some of our own from the gut microbiome, that can harm gut and body. Here’s how.
6. “Leaky Gut” (Gut Barrier Dysfunction)
The red arrow represents a “bad guy” antigen loosening the tight junctions by causing the gut cells to release a protein called “zonulin,” which impairs the defensive gut barrier. Two common potential “bad guy” dietary protein antigens are gluten and dairy casein. While many antigens come through and are “good guys,” your gut immune system and brain must recognize the “bad guys.” Then they protect and defend you by mounting an inflammatory, immune, and allergic response, which can include mast cell activation and histamine release.
7. Bad for Your Gut & Its Brain
All disease begins in the gut. A vicious cycle can be established as your defensive responses result in even more leaking and gut damage, commonly manifested as enteropathy symptoms. However, gut symptoms may not be present to warn you about what’s happening.
8. Bad for Your Body, Brain, & Nervous System
Unlike Las Vegas, what happens in the gut doesn’t stay in the gut. Chronic inflammation, immune dysfunction, allergy, and histamine can affect any organ system, including your brain and nervous system. This is, in part, why so many different bodily symptoms and diagnoses can be present, as described at the end of Article 3 in the section: “Associated Disorders: Mind/Body—BrainS/Gut Dysfunction.”
Now you’re ready to appreciate the relationship of food with enteropathies.
Loose Stools and/or Diarrhea After Eating
Urgent, unexpected, loose bowel movements or diarrhea after eating often associated with abdominal pain/discomfort and abdominal bloating/distention implicate one of three possibilities.
Rapid Colon Response to Eating
(Exaggerated Gastrocolonic Response)
After eating — during the digestive phase (Figure 5.2) — and commonly in the morning after breakfast, the upper gut (stomach and duodenum) signal the colon by reflex to activate the strong muscular contractions (high-amplitude propagating contractions) (Figure 5.1). Larger and/or fatty meals tend to be the most stimulating, but specific foods can be responsible. It’s nature’s method for making room later by emptying the colon and rectum of stool. This reflex accounts for infants having a bowel movement during or shortly after feeding. Many take advantage of this reflex to have a convenient and predictable movement after eating. However, it’s commonly sent too strongly and inconveniently with enteropathies, such as irritable bowel syndrome (IBS).
There are two types of impaired absorption of carbohydrates, fat, and nutrients by the small intestine.
- Maldigestion describes a disorder occurring within the intestinal tube (lumen). An example is exocrine pancreatic insufficiency related to chronic pancreatitis.
- Malabsorption describes malfunction or disease of the intestinal wall. Examples include carbohydrate malabsorption of FODMAPs and Sucrose Intolerance.
However, the term “malabsorption” is commonly used to refer to both disorders, which is what we’re going to do in our enteropathy series.
Carbohydrate malabsorption results in water being drawn into the gut and bacterial fermentation by the gut microbiome and release of gases. Enteropathy symptoms ensue. SIBO is a common cause (Article 4).
Bile Acid Malabsorption (BAM)
Bile acids manufactured by the liver and stored in the gall bladder (Figure 5.1) are like detergents, helping with digestion and absorption of fat. Later, bile acids are absorbed in the lower small intestine (ileum), where they are returned to the liver through the bloodstream to be re-cycled and re-used. BAM is caused by the abnormal presence of the bile acids in the colon, where they interfere with stool solidification and stimulate colon contractions. There are many causes, including having the gall bladder surgically removed, IBS-D/M, Crohn’s disease, and surgical removal of ileum. BAM is treatable with drugs called “bile acid sequestrants.”
True food allergies are much less common in adults than food intolerances or sensitivities. However, recent studies show adult food allergies are more common than had been thought, with approximately 10 percent of adults having at least one food allergy.
In a traditional food allergy, the body reacts to the antigen (“bad guy”) by mounting an inflammatory-immune system “defensive” attack generated by an immune system component called the “IgE antibody.” Antibodies are a type of protein the immune system uses to recognize and defend from “bad guy” antigens.
This response occurs immediately or very quickly (within seconds to two hours) after the allergy-provoking food or substance is ingested. Gut symptoms include swelling of the tongue or mouth, trouble swallowing, nausea, vomiting, abdominal pain, and diarrhea. Body symptoms include anxiety, swelling of the lips, wheezing, trouble breathing, hives (urticaria), dizziness, rapid pulse, weak pulse, and low blood pressure. At their worst, true food allergies can be life-threatening (anaphylaxis).
The eight most common causes of food allergies are milk, eggs, peanuts, tree nuts (such as almonds and walnuts), fish, shellfish (such as crab, lobster, and shrimp), wheat, and soy.
If food allergy is suspected, it’s usually best to work with a board-certified allergy specialist. Both patients and doctors should watch out for overpriced, scientifically unsound tests and the negative effects of misleading results on the patients’ long-term health.
An excellent website resource is Food Allergy Research & Education, or FARE.
Food Intolerance and/or Sensitivity
Food intolerance or sensitivity is much more common than food allergy. Furthermore, there is no identifiable immune system response to the offending food or substance detected by allergy testing.
“Spicy” food intolerance is very common, producing a hot sensation related to a compound called “capsaicin.” However, the term, “spicy food” includes many ingredients. Examples are onion, pepper, chili pepper, garlic, and ginger.
Some foods cause food intolerance by interfering with the carbohydrate breakdown function of enzymes from the small intestine and amylase from the pancreas, resulting in malabsorption.
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