Digestion 101

Welcome to The Perfect Stool: Understanding and Healing the Gut Microbiome. This is your host, Lindsey Parsons, and today I'm going to be talking about the basics of digestion and how it works. And hopefully this will help you better understand what could be going wrong and where you may need to intervene to fix things, because Your own understanding and intuition about your body is the most important piece in getting better. But before I get started, if you haven't yet followed or subscribed to the show, be sure to do so. If you want to get transcripts of the podcast, pop over to my website, HighDesertHealthCoaching.com, and sign up for my newsletter. You'll also get my free ebooklet called Finding Your Root Cause Through Stool and Organic Acids Testing when you sign up. If you haven't yet done my quiz on which stool or functional medicine test would help you uncover your root cause, you can find a link in the show notes and take that. And now on to the show. So I'm going to describe the digestive process when it's working well, which may help you pinpoint where things may be going wrong for you, as well as give you an idea of the symptoms when a certain part of your digestion is off. And I'll be focusing mostly on functional digestive issues, as those are the kind I work with clients on, as opposed to mechanical issues, which a conventional gastroenterologist is going to be best equipped to handle, although I may mention a few of those. And I will preface this by saying that, of course, this isn't comprehensive, but rather a summary of some of the most common issues I see in clients. So first of all, before you eat, as you even think about eating or smell your food before eating it or while cooking it, this is going to alert your brain to start the flow of saliva in your mouth, which contains salivary amylase, which helps break down starches in your food into simpler sugars. Then next, if you don't shovel your food down too quickly, you'll ideally be chewing each bite a good 20 or 25 times so that it's a fine mush and it mixes well with those enzymes. Then as you swallow, your food travels down the esophagus to your lower esophageal sphincter, which will open up to let the food into your stomach. And now, hopefully, the pH in your stomach is ideal, meaning it's not too acidic or too alkaline, although the stomach with its acid is quite acidic, with a pH usually in a range of 1.5 to 3.5. But when it's not acidic enough, or you have a lack of stomach acid, which is called hypochlorhydria, it can lead to the opening of the lower esophageal sphincter, which is sensitive to pH and closes when the pH drops under 3.0. And that will trigger the escape of stomach acid into the esophagus, and then you can have the sensation of GERD, or gastroesophageal reflux disease, also known as heartburn. And stomach acid tends to decrease with age, but can also decrease due to the presence of H. pylori or Helicobacter pylori, which is the bacteria that causes ulcers and stomach cancer when it possesses certain virulence factors. Other factors that impact stomach acid are alcohol use, poor diet, not being in a proper rest and digest or parasympathetic state while eating, stress and food sensitivities, as well as pharmaceuticals like antibiotics, proton pump inhibitors, or PPIs, and antacids. So insufficient stomach acid can lead to maldigestion of proteins and their components, amino acids, which can impact the lining of the stomach because it's formed of those proteins, and it can lead to leaky gut and put stress on the pancreas as well to produce enzymes to complete the digestive process. And those enzymes themselves are composed of amino acids. So when you have undigested proteins that leak into the abdominal cavity, that can then trigger autoimmune reactions as your immune system is targeting the proteins in other parts of your body that look similar to the offending proteins. So low stomach acid can also lead to overgrowth of Candida, parasites, and bacteria, which are normally killed off or kept in check by stomach acid. And it can also lead to mineral depletions in the body. Another possible reason for GERD, as proposed by Norm Robillard, who wrote the Fast-Track Diet and appeared on episode 41 of this podcast, is an overgrowth of bacteria in the small intestine feeding on mal-digested carbohydrates, which leads to the production of gas., and then that gas can put upward pressure on the stomach, causing acid to be pushed back upwards. And the maldigestion can be the result of excess starches in the diet or excess bacteria, as well as insufficient pancreatic enzymes to help digest the starches. And then that upward pressure can also happen as a result of a hiatal hernia. But back to your stomach. When the food arrives here, your stomach's G cells release a hormone called gastrin, which triggers the stomach to release gastric juice, which is composed of water, mucus, hydrochloric acid, pepsin, and intrinsic factor. And the churning motion of your stomach helps to mix up the food with gastric juice and break it down. Then the pepsin, in combination with the acidic pH produced by the hydrochloric acid, breaks down proteins into amino acids. So there's a few things that can go wrong at the level of the stomach that can cause you problems. Gastritis, or inflammation of the lining of the stomach, can come about due to a poor diet, excess alcohol consumption, overuse of NSAIDs, or nonsteroidal anti-inflammatory drugs, especially ibuprofen and naproxen sodium, and H. pylori overgrowth, which can be the result of lower gut immunity due to stress. And while virulent strains of H. pylori can cause ulcers and stomach cancer, even nonvirulent strains can cause GERD and bloating after eating, stomach pain, especially on an empty stomach, nausea, and other symptoms like lack of focus, especially in children, and constipation, diarrhea, or even insomnia. And while tests of people with symptoms of GERD have shown that hypochlorhydria is the most common cause, meaning low stomach acid, that's roughly 80% of the time. You may actually have excess stomach acid or hyperchlorhydria, which is commonly treated with PPIs by conventional doctors, whether or not the state of your stomach acid is actually known, which is pretty rare because few doctors have the ability to perform a Heidelberg test, which actually measures your stomach acid. Hyperchlorhydria is also common in the early stages of an H. pylori infection, but usually turns into hypochlorhydria over time. But it's important, even if you do have excess stomach acid, to not stay on PPIs long-term. Usually a course of 2 weeks is recommended, and then other causes of your issues should be investigated. So after the stomach, the food goes through the pylorus into the small intestine or small bowel, where it's broken down further with enzymes produced by the pancreas. The primary types being amylase for breaking down starches, proteases, also called proteolytic enzymes, proteinases or peptidases for breaking down proteins, and lipase for breaking down fats, along with bile. Bile is produced by the liver and stored in the gallbladder, and it emulsifies fat, meaning it breaks it down into micro droplets. And then also involved in the final stages of digestion of carbohydrates and protein are the brush border enzymes that are embedded in the microvilli, or hair-like structures lining the small intestine, the most well-known of which is lactase, which breaks down lactose, the sugar in dairy products. Your genetics determine the persistence of lactase activity, which many people lose by adulthood, like me, making them lactose intolerant, whose symptoms are gas, painful or soft or even liquid stool, bloating, cramping, and discomfort after eating while eliminating lactose. Which is highest in soft cheeses, milk, and ice cream. Issues at this level can be related to insufficient pancreatic enzymes, which can have many causes. The official name of this is exocrine pancreatic insufficiency, or EPI, whose most common cause is chronic pancreatitis, or inflammation of the pancreas, which can come about from alcohol abuse or gallstones in the gallbladder. Ongoing inflammation will damage the cells of the pancreas, leading to a decrease in pancreatic enzyme production. And then other potential causes of EPI are celiac disease, IBD, or inflammatory bowel disease, diabetes, pancreatic cancer, and weight loss or other digestive tract surgery. Symptoms of EPI are either constipation or diarrhea, abdominal pain, bloating and gas, and fatty or pale-colored oil or floating smelly stools. Returning to the gallbladder, you can also have issues impacting your digestion originating in the gallbladder, such as gallstones, clogged bile ducts, sludgy bile, or insufficient bile. Which is a given if you've had your gallbladder removed. Although the liver produces bile, it's stored in the gallbladder, and you won't have enough to digest a higher-fat meal if you've had your gallbladder removed. So signs of insufficient bile or fat maldigestion include trapped or bad-smelling gas, stomach cramps, diarrhea, erratic bowel movements, weight loss, and pale-colored stools. Having problems with fat digestion or having had your gallbladder removed does tend to lead a lot of people to try to avoid eating fat, which is a mistake because it's part of a healthy diet and it is necessary for the absorption of your fat-soluble vitamins A, D, E, and K, as well as fat-soluble vitamin-like compounds like CoQ10. So if you've had your gallbladder removed, you should continue to eat fat but support your gallbladder with something like bile acid factors. If your bile is insufficient for other reasons, you may need to stimulate bile production with bitter greens, green leafy vegetables, beets, artichokes, pickles, grapefruit, lemons, limes, and there's juices and zest, spices such as fenugreek seeds, cinnamon stick, turmeric, ginger, or drinks like roasted dandelion root tea, lemon tea, celery juice, and coffee. There are also lots of things that can go wrong at the level of the small intestine that can impact digestion. From the bacterial perspective, there's SIBO, or small intestine bacterial overgrowth, which is usually caused by stagnation in the small intestine due to a variety of causes and leads to a buildup of excess bacteria and general dysbiosis. Or an overgrowth of the wrong types of bacteria. This can cause painful bloating and distension of the abdomen after eating, and if the bacteria produces hydrogen, usually is accompanied by diarrhea or soft stool. If your overgrowth is of hydrogen sulfide-producing bacteria, then you'll likely have gas that smells like sulfur or rotten eggs and excessive belching. And other signs of possible hydrogen sulfide SIBO include intolerance to sulfur-containing foods and supplements, weight loss, brain fog, exercise or stress intolerance, burning bladder syndrome, elevated heart rate, insomnia, and low blood pressure after eating. Hydrogen sulfide SIBO is also associated with ulcerative colitis, Crohn's disease, and colorectal cancer. Then another thing that can go wrong is intestinal methanogen overgrowth, or IMO, which used to be known as SIBO-C or SIBO with constipation. And that's an overgrowth of archaea, which are like bacteria but of a whole different domain, including Methanobrevibacter smithii, and Methanosphaera statminae, which produce methane gas by metabolizing the hydrogen produced by the bacteria that ferment carbohydrates. And you'll often have bloating gas with a metallic smell when this happens. Another possible problem at this level is an overgrowth of Candida, which is a normal resident of your gut but can overgrow and even become systemic in severe cases where it can form hyphae or sort of tails that go out between cells lining the small intestine. And usually bloating after eating, food sensitivities, skin issues, and brain fog are signs of invasive candidiasis. Any of the above small intestine issues can lead to a case of intestinal permeability or leaky gut, which means that bits of not quite digested food or bacterial body parts called lipopolysaccharides or LPS can escape either through broken down cells or between cells and get into your system, activating your immune system and then often leading to autoimmune diseases. But back to the normal digestive process. After the small intestine, food moves through the ileocecal valve to enter into the large intestine. Some people have mechanical issues with this valve staying chronically open or closed, and chronic constipation and tenderness in the lower right quadrant are signs that this may be an issue, and it can also be a root cause of SIBO. You can actually manually reset this valve, and I'm gonna link to a video about how to do that. And I should also mention the role of the vagus nerve in all this, because the vagal nerves carry signals between your brain and digestive system, and damage to the vagus nerve from, say, a traumatic brain injury, like concussion, diabetes, stomach surgery, or certain medications, or just dysfunction from emotional trauma and stress can impact your digestion, causing problems like gastroparesis, or food not moving from your stomach into your intestines properly, or SIBO. One simple way to check your vagus nerve function, which is described in the book Accessing the Healing Power of the Vagus Nerve by Stanley Rosenberg, is to look at your uvula, or that thing that hangs down in the middle of your throat, and look in the mirror and say, ah, ah, ah. And look if it pulls up to the right or left as opposed to straight up and down. If it does, you may have vagus nerve issues. If this is the case, there are exercises listed in that book that can help you return to normal vagal tone. And of course, you can have autoimmune issues all along the way in your digestive tract, starting in the stomach where pernicious anemia is an autoimmune attack on the parietal cells lining the stomach that produce stomach acid and intrinsic factor, which allows you to absorb vitamin B12. Or you can have post-infectious IBS or irritable bowel syndrome, which is an autoimmune attack on a protein called vinculin. Which helps the migrating motor complex function to remove food from your small intestine on a regular basis. Or you can have celiac disease with, which is an autoimmune attack on the microvilli lining the small intestine when you eat gluten. And common signs of this are stomach pain, fatigue due to malabsorption of nutrients as the microvilli deteriorate, and diarrhea. You can also have other food sensitivities and intolerances such as non-celiac gluten sensitivity or lactose intolerance, which are two of the most common. Or you can have inflammatory bowel disease, which is an autoimmune disease that can manifest as ulcerative colitis or Crohn's disease. Crohn's involves plaques of diseased ulcerated tissue anywhere from your mouth to your anus, and in its most severe form can lead to twists and strictures in the intestines openings, or fistula, in the perianal area, anemia, shortness of breath, and inflammation in your skin or joints. Common earlier signs of Crohn's are pain, abdominal cramping, diarrhea, fatigue, fever, blood in the stool, loss of appetite, weight loss, food sensitivities, a sense of incomplete elimination after bowel movement, and bowel urgency. And colitis takes many forms such as pancolitis or microscopic colitis or ulcerative proctitis, et cetera, depending on its location and form, but it always involves inflammation and ulcers in some part of the colon. Signs of colitis include abdominal pain, diarrhea, bowel urgency, blood and/or pus in the stool, weight loss, rectal pain, nausea, vomiting, loss of appetite, chills or fever, and anemia. So back to normal digestion. When the food reaches your large intestine, normally you'll be absorbing water, minerals, and some remaining nutrients from your food. And if you have a healthy fiber-rich diet, you'll also have lots of fiber left over for the bacteria, which are most abundant in your large intestine, to ferment. The bacteria will also be providing nutrients themselves, specifically B vitamins and vitamin K, from that fermentation process. And they'll be extracting the short-chain fatty acids butyrate, propionate, and acetate from the fermentation process. Butyrate has been the target of a lot of research recently, and I'm sure you've heard me mention it as it produces 70% of the energy for the cells lining the large intestine or the colonocytes, and it helps maintain a hypoxic or oxygen-free atmosphere in the colon. So the colonocytes, when they use the butyrate for energy, they break it down and, and also the other short-chain fatty acids through a process called beta oxidation. And that process requires a lot of oxygen. And when there's a lack of fiber for producing butyrate or following antibiotic use, you can have a breakdown of this process. Which leads to a loss of that gut barrier function and a subsequent increase in oxygen in the colon. That increase in oxygen favors expansion of Proteobacteria, which is a phylum of bacteria that contains a lot of gut pathogens like E. coli and Pseudomonas and Campylobacter, which are facultative anaerobes, meaning they can live in the presence of oxygen, which helps them outcompete the beneficial obligate anaerobes, particularly the Clostridia, which are butyrate producers. So it becomes a vicious cycle. I will link to the Lucy Mealing article explaining all about this particular type of dysbiosis. But what I've found with my clients is that if you tend to have loose, messy stool, it's often the result of this kind of dysbiosis. And supplemental butyrate in the form of probutyrate or tributyrin is helpful in breaking this cycle. And of course, eventually getting onto a good high fiber diet. And I should probably mention constipation at this point because obviously that's something else that can go wrong. Having fewer than one bowel movement a day or having stool that's very dry and hard or even to the point of rabbit pellets. Hard to pass, or feeling incomplete is considered constipation. You may also see breakthrough diarrhea as well in the context of constipation, or what's considered IBS-M, or mixed. And constipation can be the result of dehydration, lack of exercise, a low-fiber diet, changes to routine, and intolerance to or large amounts of dairy products, stress, chronic holding of bowel movements, or certain medications. And all that can lead to anal fissures, diverticulitis, or infected pouches in the wall of the large intestine, or hemorrhoids, which can all cause pain in the colon, and in the case of anal fissures and hemorrhoids, can cause bleeding, which will show up as bright red on the toilet paper. But if everything is going well and properly with your digestion, you'll instead have 1 to 3 regular bowel movements a day, around a 3 or 4 on the Bristol Stool Chart, which pass easily and completely, result in a clean wipe of the toilet paper most of the time. That was a lot. I hope that gives you some leads for what's going on with your digestion. But if you've been through the conventional medical system with no answers, my specialty is helping folks figure these things out. You can set up a free 30-minute breakthrough session to talk to me about what you've been going through. If you want, I can let you know if I think it's something I can help you with and tell you about my 5-appointment gut healing program, and you can decide if that seems like a good fit for you. Or you can also just sign up for a single appointment. Links for all those are in the show notes. And if you'd like to connect with me online, you can follow my High Desert Health Facebook page, join my gut healing Facebook group, or join my newsletter list at highdeserthealthcoaching.com, or find me on Twitter, Instagram, or Pinterest. The links for all those are in the show notes. Thanks for joining me today, and here's wishing you all the perfect stool.