#23. Digestive Health Monday, July 19, 2021 We've been talking a lot about microbes lately. And about digestion. But there's more to digestion than meets the... microscope. Beyond our inner biomes, important roles are played by nerves, blood, and hormones (Costa et al., 2000; Latorre et al., 2016; Matheson et al., 2000). Let's describe those roles with a story. A second-person omniscient one. This: It's 5:35pm. You're driving a Hyundai Elantra. It's purple, but you didn't choose the color. At the moment, you're in line. There are six other cars between you and the drive-through window at the local Hamburger King. You've been sitting in this line for about ten minutes now. And salivating for at least nine of them. You can't help it; the aroma of burned meat juice and fry oil is so much more potent than the cloud of car exhaust engulfing your Hyundai Elantra that has nearly 190,000 miles on it. By the time you arrive at the menu board to place your order, you've already swallowed a Nile of your own spit. Like a Pavlovian dog, your body is preparing to digest the food that it anticipates biting. Drool contains enzymes that begin to break down your carbs and fats before they ever get to your stomach: amylase for carbohydrate and lingual lipase for fat (Tucci et al., 2010). Finally, you pull up to the window and receive a cheap paper bag containing the food you've been enzyming about: a hamburger wrapped in even cheaper paper. You release it from its wrappings and ravenously burger your mouth hole. As long as you don't swallow into your trachea and cough about it, the next stop is your stomach, where the residents include hydrochloric acid, gastric lipase, and pepsin (an enzyme that breaks down proteins; Menard et al., 1995). Now you really start bustin' up your foodstuffs, churning it into a pulpy goop called "chyme." Once the chyme is sufficiently gooped, the stomach begins slowly injecting it into the small intestine. Around this time, the gallbladder and pancreas squirt some secretions into that tube to prepare it for the incoming chyme, and to help digest and absorb it when it arrives (Turumin et al., 2013; Whitcomb et al., 2007). Whatever doesn't get absorbed is passed to the large intestine. This is basically a trash compactor and holding silo for feces, but it does absorb water and transport some loitering electrolytes (Kiela et al., 2016). It's all poop from there. Poop and tips. You can poop on your own time, but let's do tips together: Tip 1) At any point between your mouth hole and the toilet bowl, digestion can be impaired. There are plenty of rascals that can stir up trouble, but stress is a big one. Both physical and emotional. You have hundreds of millions of neurons in your gut (collectively known as the enteric nervous system), roughly the same as you have in your spinal cord (Furness, 2012). It's a very nervous bundle of meat. That's part of the reason stress can exacerbate symptoms of gastrointestinal disorders in those who already suffer, and can induce nausea and diarrhea in others (Fond et al., 2014; Haug et al., 2002; Mayer, 2000). If stress is attacking you today, and you're looking for ways to defend against it, try meditation or controlled breathing techniques. Done correctly, they can have a meaningful effect on our bodily responses to life's stressors (Moszeik et al., 2020); Zaccro et al., 2018; Ma et al., 2017). Tip 2) Grocery stores have a lot of variety on their shelves. That doesn't mean the full breadth of that variety must inhabit your dinner plate though. Certain foods (e.g., dairy, wheat, soy, peanuts) are more likely to induce indigestion than others (e.g., avocado or carrots). If you're going through life painfully bloated, distended to the PSI of a car tire, that's not normal. It's probably something you're eating. Constipation and diarrhea as well if they visit with any regularity. A reasonable experiment is to eliminate all of the probable culprits for a while and see how you feel. Better? If so, start reintroducing foods one at a time - gradually, patiently - and notice if symptoms return. A drastic "elimination diet" shouldn't be maintained for too long without careful management of micronutrient profiles. But short-ish term, it can teach you how to let the air out of your intestinal tires and poop like a person (Lim et al., 2018; Newberry et al., 2019; Pastorello et al., 1989). Tip 3) Hydration. Digestion and excretion are both pretty tough without it (Jequier et al., 2010). Alongside insufficient fiber, a stool-arresting medication cabinet, and T-Rex portions of meat, poor hydration is a common cause of constipation (Popkin et al., 2010). If your bowel movement requires the assistance of a midwife, or if you have enough time to read while sitting on the toilet, you're doing something wrong. Especially if you're heaving and grunting while turning pages. Simply ingesting more fluids will soften that rocky lump and make the bathroom a more private and less literate space (Liska et al., 2019).