The Microbiome Connection Part 1: by Mark A. Pimentel
In this book, the author explains how the microbiome of the gut can impact gut illnesses, two of which are highlighted in this blog: IBS and SIBO. Gastrointestinal illnesses are common and it’s important that they are talked about. Let’s start with IBS.
If you’ve had the following symptoms for three or more months, you have IBS: abdominal pain and/or discomfort, diarrhea, constipation, bloating, gas, urgency, incomplete evacuation, relief or worsening of pain with defecation, brain fog, early satiety (a sense of fullness without having eaten much), or both diarrhea and constipation. The last symptoms, diarrhea and constipation, may strike you as impossible, but they have now been classified as one of the three distinct types of IBS. First, there is IBS-C, meaning IBS with constipation. This type is found in 35 percent of patients. Second, there is IBS-D, which is IBS with diarrhea, found in 40 percent of patients. Third is IBS-M (mixed type), which is IBS with alternating bouts of diarrhea and constipation, found in 23 percent of patients. In this category, many patients don’t know whether they will be hit with diarrhea or constipation. During the course of one day, they might be constipated in the morning, but have diarrhea in the afternoon. And within one bowel movement, their stool may be hard at the beginning and watery at the end. So, we now consider IBS-D and IBS-M as one type of IBS disease—Non-constipation IBS—and IBS-C is possibly a different disease, Constipation IBS. Let’s talk about your digestive system. The first point of contact with the digestive system is your mouth, where food begins the journey of digestion. When you think about eating, your brain tells your gut, “Get ready, food is coming.” This turns on the production of saliva, which contains enzymes to begin the breakdown of food. At the same time, the brain sends signals to your stomach and to the colon via the vagus nerve. The signals flip a switch to convert the digestive system from fasting state (“cleaning mode”) to feeding state (“grinding and digesting mode”). The vagus nerve signals also ramp up the pancreas to secrete digestive juices and insulin, the stomach to produce more acid, and the gallbladder to squeeze out bile to help liquify fats and add more blood flow to the gut to gather up nutrients. When you take your first bite of food, the vagus nerve in your brain is excited, and as you swallow it becomes even more excited. By the time the food reaches your stomach, it’s really excited. The brain signals increase in intensity as the food moves closer to the small intestine, where absorption occurs. Remember, the gut has two modes: feeding (digestion) and fasting (cleaning). Two to four hours after you eat and digest a meal, the feeding mode turns off and fasting mode begins. It takes about two hours to digest carbohydrates, and about four hours to digest heavy fatty food or high- protein food. During the fasting mode, waves of electrical activity induce the gut to sweep residual undigested material through the digestive tract. This “housekeeping” role is known as the migrating motor complex. Most often, but not always, this procedure begins in the stomach. The oblong-shaped pancreas is located behind the stomach in the upper left abdomen. It converts food and other nutrients into fuel for the body, and produces pancreatic juice that enters the duodenum of the small intestine. The digestive enzymes secreted by the pancreas help break down proteins, carbohydrates, and fats. The pancreas also produces the hormones insulin and glucagon to help regulate blood sugar. Finally, the pancreas secretes bicarbonate that neutralizes the stomach acid. A balanced pH in the small bowel is crucial for the function of mucosal cells and digestive enzymes. The liver, the largest solid organ in the body, is found in the upper right quadrant of your midsection, just above the colon. It plays an important role in the body’s immune system, as it is the epicenter of detoxification: it will detoxify any toxin it encounters. Alcohol is the most well-known toxin broken down—or metabolized—by the liver. The liver also produces bile acids—the yellowish-brown enzymes that eliminate cholesterol from the body and aid in gut motility for digestion and absorption of fats in the small intestine. Bile acids also contribute to the color of your bowel movements. The gallbladder is a pear-shaped, hollow organ that sits just beneath the liver. In between meals, during the fasting phase, the gallbladder processes, stores, and concentrates bile from the liver. When the gut needs bile, the gallbladder squeezes the right amount out to help digest fats and other components. Once in the gut, some of the bile gets reabsorbed into the blood from the ileum, the last section of the small intestine, and recycles back into the liver. If your gallbladder is removed or is not functioning properly, bile will flow straight from the liver into the small intestine and eventually to the colon, often resulting in diarrhea. It’s important to note that when bacteria encounter bile, they convert it to toxic bile acids (such as deoxycholic acid and lithocholic acid), which are believed to cause diarrhea. This is known as bile acid diarrhea (BAD) and is different from SIBO, but it’s worse when SIBO is present. One of the main causes of bile acid diarrhea is SIBO.
