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The 3 Causes of Constipation
by Clarissa Palencia
Editor: Kate Sweeney
Constipation is a topic often misunderstood or swept under the rug.
Yet, it is fairly common, affecting 15% of the population worldwide.
It may affect you.
When we are constipated, we can feel pretty awful. Our quality of life is usually affected.
For example, you may not want to go grab a bite to eat if you have no appetite because you feel full and bloated. Or, you may not be able to exercise the way you want because of lower abdominal discomfort. These challenges can also affect your mental health.
There is hope, and you can find relief.
What is constipation?
Constipation, as defined by the Rome IV criteria, is:
Less than three spontaneous bowel movements per week
Struggling to go, with more than a quarter of attempts resulting in strain
Passing hard, lumpy stools (Bristol type 1 or 2 on this chart) 25% of the time
Feeling like you are incompletely evacuated 25% of the time
Requiring manual help to get things moving in at least 25% of the time
You may have constipation if you are experiencing several, or just one, of these symptoms. Even if sometimes, you have diarrhea (we’ll get to that later).
However, some people have a bowel movement twice a week, and think nothing of it. For that particular person, it may be normal and not cause any problems.
As Tamara Duker-Freuman, an excellent gastrointestinal (GI) dietitian, states in her book ‘Regular’- ‘if it ain’t broke, don’t fix it.’ In other words, if you are not bothered by your regularity, then it does not need attention.
What other symptoms result from constipation?
While the Rome IV Criteria is the textbook definition, many people struggle with other symptoms that come along with constipation.
These include:
Abdominal bloating - the feeling of trapped gas, pressure or discomfort in the lower abdomen
Abdominal distention - the visible increase in abdominal girth that may come with bloating
Overflow diarrhea- Diarrhea caused by increase pressure around a dried up piece of stool
Reflux & nausea- While not discussed often, a back of stool can affect the upper GI area. This means that pressure from the stool burden can put pressure on the diaphragm and stomach and result in reflux or nausea when eating larger meals, or in some cases, even ‘normal’ sized ones.
What are the 3 most common causes of constipation?
There are three main causes of constipation. These are:
Slow- transit constipation
Low fiber intake
Pelvic Floor Dysfunction
Slow-transit constipation
Slow-transit constipation is constipation that results because the motility, or movement of the GI tract, is slow. Constipation-predominant Irritable Bowel Syndrome (IBS-C) is one form of slow transit constipation, and typically also comes along with pain. Besides IBS-C, certain medications like opioids, antidepressants and antipsychotics can slow down GI transit.
Common symptoms of this type of constipation include distention, abdominal pain, and incomplete bowel movements.
Slow transit constipation is treated in various ways. It may include a bowel regimen, involving either osmotic or stimulant laxatives. It may also involve medications that speed up the motility of your gut. For some people with IBS-C, they may benefit from a lower-FODMAP diet. Having coffee or other hot liquid in the morning with breakfast and regular meals/snacks can also help more regular movement of the GI tract.
All of these treatments are highly individualized, and you should always talk to a professional before starting them.
Low- fiber intake
Going regularly, but stool is dried and in little pebbles? Or, going infrequently and stools are pretty dray as well? This may be a sign of low-fiber intake constipation. The American Heart Association recommends 25-30 grams total dietary fiber intake per day.
There are two types of fiber: soluble and insoluble. In the digestive system, soluble fiber dissolves in water (think oatmeal) and becomes the goo that holds the stool together and bulk it up. Common food sources are the inside of beans, oats, chia seeds, apples, kiwis and more.
Insoluble fiber does not dissolve in water and passes through the digestive system intact. Think about the corn you may see in your stool- this is normal! Insoluble fiber is in leafy greens, fruit skins, potato skins, and seeds. It is what we often call ‘roughage’. It helps push against the intestinal walls and promote movement of the GI tract.
A balance of both soluble and insoluble are important to maintain frequent bowel movements, softening stool consistency, and preventing it from being too liquid.
I often see people with constipation from low fiber as having too much insoluble fiber (lots of salads, raw veggies and fruits, tough grains like quinoa) and too little soluble fiber. Having more soluble fiber can sometimes do the trick. In fact, one study showed that two kiwis per day was as effective as supplementing fiber in the diets of people with chronic constipation.
Pelvic Floor Dysfunction (PFD)
Never feeling fully evacuated after a bowel movement? Have you tried more fiber or laxatives and found no benefit? This may be because you’re struggling with PFD.
Our pelvic floor plays a role in pooping, peeing and sexual function and is made up of multiple muscles that control these processes. When we have PFD, it means that one or more of the muscles is not functioning properly and results in constipation, painful vaginal intercourse, inability to hold in urine and more.
There are many causes of PFD that lead to constipation. No matter the reason, the end result tends to be getting backed up with stool, which can actually cause upper GI issues like nausea and early fullness after meals.
Your doctor may do a KUB (kidney, uretra, bladder) x-ray to understand if you have a stool burden and test the muscles in your pelvic floor with anorectal manometry.
PFD is most responsive to biofeedback, shifting toileting positions to be more in a squat, using suppositories and physical therapy. Food-wise, if someone is really backed up, we may also reduce the insoluble fiber in their diet and go for softer foods until their back up is resolved.
A Side Note on Eating Disorders and Constipation
For those of us struggling with disordered eating, it is not uncommon to also be struggling with GI concerns, particularly constipation. In fact, studies show that 70-90% of individuals with eating disorders also suffer from GI concerns like constipation, nausea, reflux and more. Studies show that constipation is the most common GI symptom in people with anorexia nervosa, and it is also common in bulimia nervosa and ARFID.
Some ways that disordered eating and constipation intersect are:
Our GI tract is a muscle. When we do not eat enough, our GI tract can atrophy (lose) some of that muscle. This leads to slowing of GI motility.
Since our pelvic floor is made up of muscles as well, those can also become weak and constipation can occur.
The microbiome also has been shown to be different in individuals with eating disorders versus those without, and whether or not that causes constipation is not yet known.
The nerves that innervate our gut, called the enteric nervous system, play a role in moving food along and maintaining blood flow. These nerves respond to stress and anxiety, which can impact how quickly or slowly our gut moves.
When helping people who have constipation and disordered eating, I make individualized recommendations. I find that helping clients find some relief from constipation, whether that means increasing intake or frequency of eating, having hot liquids in the morning and/or using a gentle bowel regimen, can really help alleviate anxiety and contribute to more confidence around eating in ways that benefit their recovery.
Closing Thoughts
You do not need to solve constipation on your own. And, I do not recommend it since the cause of it will dictate the treatment.
It is important to consult with your doctor or a GI dietitian when considering what your next steps could be to tackle constipation and ease symptoms that you may be experiencing.
Resources:
Two great, evidence based books on bloating and regularity:
Duker-Frueman, Tamara. The Bloated Belly Whisperer. NYC, NY. St Martins Publishing Group. 2020.
Duker-Frueman, Tamara. Regular: The ultimate guide to taming unruly bowels and achieving inner peace. London, England. Hodder and Stoughton, Ltd. 2023.
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