Our digestive tract is a complex system that relies on multiple factors to keep it regular. Its primary role is to break down the foods we eat, absorb the nutrients we require, and rid of the wastes we don't need. For some people, having a daily bowel movement is regular as clockwork, whereas others may go days on end before their next bowel movement. However, a daily bowel movement is not the only sign you should pay attention to when evaluating your gut motility. The consistency of the movement is also important, with denser movements often indicating your gut motility is lagging, while loose movements mean motility is rushed. Having a daily bowel movement is often considered to be a staple indication of overall health, as well as a telltale sign of the state of your gut environment. And while everyone's norm may look different, consistency is critical nonetheless. The most common factors that affect regularity are often diet, exercise, and fluid intake. However, bowel function is fundamentally a nervous system response, meaning it can be manipulated beyond simple lifestyle factors. In order to help you hack gut motility, let’s first break down the actual mechanism of how a bowel movement happens, and the neurotransmitters and nutrients that maintain its function.
What Stimulates Bowel Movements? The gut maintains is own unique enteric nervous system, which acts independently of your autonomic system to create muscular contractions known as peristalsis. Peristalsis propels food through the digestive tract and eventually out of the body. In order for this system to function correctly, it requires regular signalling of its muscles to release and contract, which are regulated by the neurotransmitter, acetylcholine. An abundance of acetylcholine binds to cholinergic receptors to encourage contraction, and the ultimate breakdown of acetylcholine encourages relaxation, creating the rhythmic waves of peristalsis we desire.
How Can You Increase Gut Motility? The moral of this potentially overly science-y story is proper acetylcholine management = proper gut motility. This neurotransmitter is a combination of two primary molecules: acetyl CoA and choline, formulated via the enzyme choline acetyltransferase (ChAT).
First, we need to create acetyl CoA, which is relativity easy to do since in the nerve cell, its primarily accomplished by converting glucose into acetyl CoA during glycolysis (figure 1). Glucose is ingested naturally via carbohydrates, so step one is to ensure you're ingesting a sufficient amount of complex carbohydrates each day (this is one of the reasons why some people who follow a low-carb or SCD, FODMAP, or ketogenic diet may notice more constipation). Step two is to ensure these carbs break down into their desired metabolites, which requires the right amount of thiamine, or vitamin B1. This vitamin upregulates a critical enzyme known as pyruvate dehydrogenase and supports the conversion of glucose into acetyl CoA instead of lactate.
Funny enough, the most commonly fortified thiamine foods tend to be processed carbohydrates, which are often the first things we cut out of our diets when we want to make healthier eating choices. The very cause of irregular bowel movements could easily be a lack of thiamine in your diet, which can be remedied by increasing the intake of vitamin B1. Most adults should consume at least 1.2 mg of thiamine daily, and children between the ages of 1 and 18 should get between 0.5 and 1 mg (1). Secondly, we need the micronutrient choline, which is found in the highest amounts of fatty foods such as eggs and salmon, or vegetables like cauliflower and Brussel sprouts. It can also be supplemented in forms such as citicoline, but it's best to speak to your healthcare provider before doing so. Once you are consuming healthy carbs, choline, and vitamin B1, you also need to make sure your body is producing choline acetyltransferase (ChAT) enzymes to turn acetyl CoA and choline into our desired neurotransmitter, acetylcholine. Thankfully, ChAT production occurs naturally within the body. Butyrate is a short-chain fatty acid made by healthy gut flora via the fermentation of fibre. It has been shown to help increase ChAT production (2), as well as support healthy gut barrier function and prevent increased intestinal permeability (more commonly nicknamed “leaky gut syndrome”). Eating more fibrous veg, or consuming butyrate-rich foods, such as butter, may support gut motility. Another option could be fibre supplementation with partially hydrolyzed guar gum (PHGG), which is my fibre of choice. PHGG has been shown to decrease symptoms of irritable bowel syndrome (3,4), and benefit the growth of Bifidobacterium and butyrate-producing bacteria in the human large intestine (5), without causing the majority of side effects seen with psyllium use. Why Coffee and Nicotine Make You Poop! Most people report bowel movement stimulation after a cup of coffee, and 1 in 6 people experience constipation when they quit smoking. You’ve probably guessed by now that it's because these two stimulants have direct impacts on acetylcholine. Coffee (particularly, caffeine) actually functions as an acetylcholinesterase inhibitor, meaning it slows the breakdown of acetylcholine in the postsynaptic cleft, allowing it to provide more nerve stimulation and muscle contraction. Nicotine binds directly to the cholinergic receptors that acetylcholine activates, producing similar effects as this neurotransmitter. The take-home message... If you’re trying to quit coffee or smoking, but are fearful of the effects on your gut, know there are alternative ways to get things going without all the dangerous side effects. There are many factors causing irregular bowel movements, with a lack of acetylcholine being just one of them. If you want further help to determine the cause of irregular bowel movements or wish to discuss ways to support optimal gut health, please feel free to contact Toronto Naturopathic Doctor, Dr. Courtney Holmberg at 647-351-7282 to schedule a consultation today!