Constipation and fibers
The great myth

“if you are constipated, add more fibers to your food and things will get better”

In my years of practice as a naturopath working with constipated clients, fibers supplements have been at the bottom of my list. I have never been impressed by their efficacy, or lack thereof. Not only are they useless most of the time, but they can also be counterproductive and harmful.

We will see why in this article. We will also discuss the only instance when I find them somewhat useful to avert a crisis.

A quick primer on fibers

Fibers come from the plant kingdom. Fruits, vegetables, nuts, seeds and grains all contain fibers. They come packaged with the food we eat. They were never meant to be extracted and isolated, then sprinkled on top of yogurt.

We cannot digest fibers, but our gut flora does. This is why fiber-containing foods have an importance. This process does create a certain amount of gas byproducts though, contributing to the feeling of being bloated, which is not optimal for people suffering from gut inflammation. That is why if you have gut inflammation (colitis for instance), you should go easy on fibers.

Soluble vs. insoluble

Soluble fibers can dissolve into water to form a gel. You can find them in their natural form in fruits and vegetables. The pectin of apples for instance is a soluble fiber. Legumes (peas and beans), oats and certain seeds like chia contain a significant amount. One of the best selling soluble fibers supplement against constipation is psyllium husks. You probably heard about it.

Insoluble fibers do not dissolve into water, but they expand with water like a sponge. They are more rough and irritating to the gut. Your colon is constantly stretched by the bulk created, and constantly inflamed (more on this later).

Insoluble fibers can be found in the bran of cereals and in the skin of certain fruits (apples for instance). And as we have seen in the foods that cause constipation article, grains in general should be avoided as they might be one of your constipation trigger (you can test this hypothesis by removing then reintroducing cereals in your diet).

Fibers and colorectal disease

For years and years, the following has been hammered into our head : “if you suffer from a colorectal disease (colorectal cancer, ulcerative colitis, crohn's disease, diverticular disease, etc), you have not been taking adequate fibers”.

Some experts in the field tell us otherwise. I quote from a medical paper called “Fiber and colorectal diseases: Separating fact from fiction”(1) :

“The role of fiber in the prevention of colorectal diseases remains controversial […] The more fiber is ingested, the more stools will have to be passed. Fermentation in the intestines results in build up of large amounts of gases in the colon […] A strong case cannot be made for a protective effect of dietary fiber against colorectal polyp or cancer. Neither has fiber been found to be useful in chronic constipation and irritable bowel syndrome. It is also not useful in the treatment of perianal conditions. The fiber deficit-diverticulosis theory should also be challenged.”

So let’s summarize. The more fibers you add to your food, the more bulk you will have to pass, and the more gas you will get.

Isn’t this counterproductive in the context of constipation?

Fibers and diverticulosis

We have been told to increase our consumption of fibers if we don’t want to get diverticulosis. Ever heard that message ?

They make our stools large and bulky, they stretch the fragile mucosa of the colon, and end-up creating diverticulosis, not preventing it.

A recent study including 2104 participants(4) who underwent outpatient colonoscopy from 1998 to 2010 tells us this : 

A high-fiber diet and increased frequency of bowel movements are associated with greater, rather than lower, prevalence of diverticulosis. Hypotheses regarding risk factors for asymptomatic diverticulosis should be reconsidered.

No kidding. I will reconsider.

Fibers as constipation remedy?

Let us assume you are constipated. There is a hard plug located in your colon. Before that plug, newer stools are starting to back up.

Scenario 1 : you take psyllium husks (soluble fibers) to help with the situation. You swallow the pills, you drink a glass of water, the fibers become a gel, and that gel gets stuck before the plug. It will now stagnate, and your flora will thank you for this fantastic feast. End-result : lots of gas and bloating, and still a hard plug.

Scenario 2 : let’s say you take a couple of teaspoonful of wheat break (insoluble fibers) sprinkled on your cottage cheese. The fibers act as wire brush on your colonic mucosa and aggravate any inflammation you may already have. Further, your intestinal flora has a feast. End-result : lots of gas and bloating, inflammation, and still a hard plug.

You got the picture. Those supplements do not work at all if you are already constipated. They make the situation worse. They do not act as a stimulant nor osmotic laxative. They just provide bulk. Do you really think you needed more bulk? 

Let us look at a couple of studies. The first one(2) is a metaanalysis. It means that the researchers looked at all available studies to date (a total of 1322 articles) examining the link between fibers and constipation relief. This is what they conclude:

“Dietary fiber showed significant advantage over placebo in stool frequency. There was no significant difference in stool consistency, treatment success, laxative use and painful defecation between the two groups.”

This really makes me scratch my head. People go to the toilets more often, but defecation is still painful, there is no change in the consistency of stools, and no change in laxative use. In that case, I don’t see the point of taking fibers.

Here is another interesting study(3) including 63 patients suffering from constipation not related to organic causes. Here are the result:

Patients who stopped or reduced dietary fiber had significant improvement in their symptoms while those who continued on a high fiber diet had no change.

Of those who stopped fiber completely, the bowel frequency increased from one motion in 3.75 day to one motion in 1 day; For no fiber, reduced fiber and high fiber groups, respectively, symptoms of bloating were present in 0%, 31.3% and 100% and straining to pass stools occurred in 0%, 43.8% and 100%.

Yes, you are reading this correctly. Those who stopped consuming fibers had zero bloating, zero straining and went to the toilet every day.

Conclusion from the researchers : Idiopathic constipation and its associated symptoms can be effectively reduced by stopping or even lowering the intake of dietary fiber.

Case closed.

Fibers for constipation prevention?

At this stage, I would like to give you a very simple piece of advice: when delivered as part of vegetables and fruits, fibers are healthy and contribute to a good transit, assuming you have no existing gut inflammation. If you do, I suggest you only eat cooked vegetables and fruits, and consider looking into the GAPS diet, the FODMAPS diet or similar. 

When they are extracted, isolated and consumed as supplements, fibers become irritating to the gut, particularly the insoluble form. They become counterproductive. They are not appropriate for constipation prevention.

The only instance I sometimes recommend soluble fibers: when my clients are traveling, they have no control over the food they eat, they are used to eating a lot of vegetables and fruits, and while at uncle Henry’s, they are stuck with white rice, pasta and potatoes. In those instances, psyllium husk can help, temporarily.


The conclusion is very simple. Eat a balanced diet of vegetables, meat, fish, good fats and fruits. If you have chronic constipation, try removing all grains from your diet. 

Do not use fiber supplements, they will do nothing to help with your chronic constipation. At the opposite, they will create inflammation, bloating, increases the risk of diverticular disease, and increase the amount of stool being backed-up.

The only situation when I use soluble fibers (psyllium husk) is when the person is very sensitive to changes in her diet, is used to eating lots of vegetables daily, and has to consume a diet very poor in natural fibers for a few days. In that case, soluble fibers supplements can avert a crisis.

In general, if you have chronic gut inflammation (diarrhea alternating with constipation, colitis), reduce your amount of fibers, fruits and vegetables included, and let your gut heal. Look into the GAPS or FODMAPS diet. Consume liberal amounts of bone broth. If you want to rid yourself of constipation, you will first have to resolve your gut inflammation


(1) Tan KY, Seow-Choen F. Fiber and colorectal diseases: separating fact from fiction. World J Gastroenterol. 2007 Aug 21;13(31):4161-7.

(2) Yang J, Wang HP, Zhou L, Xu CF. Effect of dietary fiber on constipation: A meta analysis. World J Gastroenterol. 2012 Dec 28;18(48):7378-83.

(3) Ho KS, Tan CY, Mohd Daud MA, Seow-Choen F. Stopping or reducing dietary fiber intake reduces constipation and its associated symptoms. World J Gastroenterol. 2012 Sep 7;18(33):4593-6.

(4) Peery AF, Barrett PR, Park D, Rogers AJ, Galanko JA, Martin CF, Sandler RS. A high-fiber diet does not protect against asymptomatic diverticulosis. Gastroenterology. 2012 Feb;142(2):266-72.e1.


Have your say about what you just read! Leave me a comment in the box below.