Decoding Digestive Health: Part 3- Root Causes of Diarrhea & Constipation

Decoding Digestive Health: Part 3- Root Causes of Diarrhea & Constipation

Published on Tuesday, September 12, 2023 by Khara' Jefferson

Understanding the Complexities of Bowel Health: Constipation and Diarrhea

Are you having fun, OR are you worried about your bowels? 

When I worked in Emergency Medicine, I worked with a physician who was so wise and would break things down so people could easily understand them. As I close my eyes and think of all the emergency department patients who would come in with gastrointestinal (GI) issues, I can clearly hear him saying, “If you’re worried about your bowels, you’re not having fun.”

And you know what? This is so true; you cannot have fun when you’re so focused on your bowels – what will happen today? Will it be loose? Will they move? How will it affect their day?

As I discussed in Decoding Digestive Health Part 1 (Understanding Digestion and Absorption) and Part 2 (Exploring Bowel Dysmotility), diarrhea and constipation can greatly affect your life – and it’s not pleasant. Unfortunately, people with irritable bowel syndrome (IBS) typically deal with one or both (mixed) conditions regularly.

For many people, the obvious solution is to turn to traditional medicine and the drug store (over-the-counter (OTC)) remedies. Miralax, milk of magnesia, magnesium citrate, and other laxatives (bulk-forming, stool softeners, or other stimulants and lubricants) are often tried for constipation. Anti-diarrheal medications like Imodium (loperamide), Pepto Bismol or Kaopectate (bismuth subsalicylate), prescription agents, or sometimes probiotics may help decrease the frequency of loose stools. But…these are temporary fixes (despite what you may have been told).

The bigger question should be: WHY? Why am I having these symptoms? What is my body trying to tell me? That’s where the differences in traditional vs. functional medicine come in. For today, I’ll keep it basic and say that functional medicine is about uncovering the root causes of dis-ease and goes deeper than traditional medicine. (More on this in my next post, so don’t fret!)


When I hear the word “constipation,” I think DANGER! I know it may sound dramatic, but sometimes, it can be life-threatening. Constipation means someone has one or more of the following: infrequent bowel movements, having to strain to pass stool or hard, pellet-like, or incomplete stools. 

While it typically creates symptoms like headache, bloating, flatulence, and pain/cramping, it may also be implicated in diverticulosis/diverticulitis, toxin reabsorption, and even colon cancer. Here are a few root causes, but there are plenty of others:

#1- Medications

There are several prescription medications that can slow down your gut. A few examples include sleeping pills, pain medications like NSAIDs (e.g., Ibuprofen and naproxen) or opioids), iron supplements, antacids that contain calcium, some antidepressants, antihistamines (e.g. Benadryl (diphenhydramine), Pepcid (famotidine), Zyrtec (cetirizine)), some nausea medications (e.g. Zofran (ondansetron)), and even a few classes of blood pressure and overactive bladder medications. Read the drug inserts carefully when you fill your prescriptions.

#2- Excessive or Insufficient Intake of Vitamins and Minerals

So many people are taking multivitamins or supplements because they believe they are helpful, but the reality is that too much of them may be harmful. While both calcium and vitamin D are essential for building healthy bones and supporting cellular growth, excessive intake of either or both is one of the root causes of constipation. Calcium on its own can be constipating, but taking too much Vitamin D too quickly can also cause the GI tract to slow down because vitamin D triggers high blood calcium levels (hypercalcemia). On the other hand, insufficient magnesium can also cause constipation. A fine balance must be maintained.

#3- Insufficient water, fiber, or dietary fat intake

Most of you know about these since they are often overemphasized. You need adequate water intake for the GI tract to work properly. Fiber (soluble and insoluble) helps to bulk up the stool, soften it, and make it easier to pass, so adequate intake is necessary. Dietary fats help to increase the strength and forward movement of intestinal contractions (peristalsis), which helps your colon to start a bowel movement.

#4- Hormone Regulation

Hormones play a vital role in many of our body’s processes. If you have a hypothyroid state (underactive thyroid) or adrenal dysfunction (think stress and cortisol – high or low), this can also cause dysmotility.


Running to the restroom when you have the sudden urge to go can be debilitating. Diarrhea occurs when watery or loose stools occur three or more times per day. This is a type of hypermotility and can end up causing nutrient deficiencies due to decreased transit time. Some root causes of constipation and diarrhea overlap.

#1- Stress – Your body goes into fight or flight mode when it senses “stress” or “danger,” which initiates digestive changes, like intestinal cramping and diarrhea, but if chronic, it can cause constipation.

#2- Dysbiosis – When the gut microbiome becomes imbalanced, dysbiosis occurs. C. Difficile is an example of what happens when gut bacteria are imbalanced, resulting in diarrhea, as it is commonly caused by prescription antibiotic treatment.

#3- SIBO – Small Intestinal Bacterial Overgrowth – This occurs when there is an overgrowth of bacteria that aren’t supposed to be present, and an overproduction of hydrogen gasses occurs, which can cause diarrhea or constipation when it’s mediated by methane-gas).

#4- Food Allergies, Sensitivities, or Intolerances – When your body reacts to foods, it may be instantaneous or take days or weeks to show itself. Dairy is a big contributor for most.


  1. Keesling, K., Murdock, J. (2023, April 21). 8 Types of Medications that Can Cause Constipation.
  2. Li, K., Wang, X. F., Li, D. Y., Chen, Y. C., Zhao, L. J., Liu, X. G., Guo, Y. F., Shen, J., Lin, X., Deng, J., Zhou, R., & Deng, H. W. (2018). The good, the bad, and the ugly of calcium supplementation: a review of calcium intake on human health. Clinical interventions in aging, 13, 2443–2452.
  3. National Institutes of Health (NIH) Office of Dietary Supplements. (2022, October 6). Calcium.
  4. National Institutes of Health (NIH) Office of Dietary Supplements. (2022, November 8). Vitamin D.
  5. Zhang, L., Du, Z., Li, Z., Yu, F., & Li, L. (2021). Association of dietary magnesium intake with chronic constipation among US adults: Evidence from the National Health and Nutrition Examination Survey. Food science & nutrition, 9(12), 6634–6641.

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