There is a general consensus amongst health and medical professionals and the general public that we need "fibre" for our gut health, for our gut microbiome, to reduce or prevent constipation, and for our overall health.
Science is not about having a "consensus" or general agreement of a percentage of people, but of finding the truth.
There is a similar belief that constipation is caused by a lack of fibre, or that consuming MORE fibre will relieve constipation. Nothing could be further from the truth...
Firstly, the definition of constipation is: "Constipation is a condition in which you may have fewer than three bowel movements a week; stools that are hard, dry, or lumpy; stools that are difficult or painful to pass; or a feeling that not all stool has passed" (NIH, 2023).
And the definition of fibre: "Fibre is found in the indigestible parts of cereals, fruits and vegetables, which pass relatively unchanged through our stomach and intestines." (Better Health Channel, 2023). "Fibre" is just cellulose, which humans cannot digest or use.
As a Clinical Nutritionist and Naturopath, my goal for each client is to find all of the root causes of all of their conditions and symptoms. I know that all of their symptoms and conditions are caused by the same few root causes. I also know that Doctors don't think or work this way, and neither do most other health practitioners.
Constipation has many possible causes, and in one person, they can (and usually do) have multiple causes for this symptom. Constipation can be caused by:
- Nerve issues, especially of the vagus nerve and its enteric nervous system which controls the digestive tract. These nerve issues can be from poor nerve conduction, or nerve damage
- Poor stomach function. If the stomach isn't digesting your foods well, from a lack of acid and enzymes, then you can end up with constipation
- Low thyroid function. The thyroid gland controls your metabolic rate and function of every cell and organ, hence a low functioning thyroid will cause low functioning digestive system and therefore constipation
- Nutrient deficiencies. Many nutrients are needed by the body and the digestive system to work properly. Contrary to popular belief, constipation is not usually caused by a lack of magnesium, or that constipation is fixed by taking magnesium
- Low water intake. Water is not only needed for stomach function but also for digesting foods, motility of the digested foods through the digestive system, and metabolism of nutrients. Low water intake will affect stomach function and cause constipation
- Medications. Many medications interfere with normal metabolic functions to cause constipation. Ironically, long-term use of laxative medications (prescribed FOR constipation) can cause constipation as a side effect
- Stress. Stress causes many physiological, biochemical and hormone changes, which can slow down digestive functions to cause constipation
- Lack of physical activity. Exercise can stimulate digestive system function, or inactivity or a sedentary lifestyle can contribute to constipation
- Dysbiosis. An imbalance of your digestive microbiome, which is actually caused from your dietary choices and the result of how well your stomach is working...
- Lack of bile salts. From poor liver and gall bladder function
- Too many meals per day.
- Other causes.
Eating extra fibre will NOT fix constipation for any of these causes of constipation! In fact, I guarantee that eating more fibre will slow down digestive motility and CAUSE or worsen constipation. I've certainly noticed this myself.
"But, but, but... what about the gut microbiome?", I hear you say! The gut microbiome changes with each meal, based on the foods you eat, and how well your stomach is working too. The wider your food variety, and a well-functioning stomach, the better for your gut microbiome. Yes the gut microbiome can use or digest some fibre from our foods, but they are not essential nutrients.
The microbiome is not just in your digestive tract. You have trillions of microbiome on your skin, in various other tracts (reproductive, urinary, respiratory, oral cavity, and more), and in various organs and tissues too. What about the microbiome on or in these areas? Where do they get their fibre from?! They don't. They don't need it.
I've previously been concerned with people who take on a carnivore diet, about their lack of fibre and digestive issues. I've tried this for months and had no issues with constipation at all.
But don't take my word for it - it's in many studies too... Including a 2012 study finding no medical or known causes for constipation in 63 people, who were recommended to go on a NO-FIBRE diet for 2 weeks (Ho, You Mei Tan, Daud, & Seow-Choen, 2012). Those who reduced their fibre intake had a significant improvement in their constipation symptoms, while those who resumed a high fibre diet had no improvement. The no fibre group reduced their (in)frequency of their bowel movements from one every 3.75 DAYS to ONE bowel motion DAILY, which is amazing and a massive improvement. With no fibre. There were additional benefits of NO BLOATING in the no-fibre group too!
In other studies, it is found that people with constipation have similar fibre intake to those who don't have much fibre (Preston & Lennard-Jones, 1986), or that those with chronic constipation have worse symptoms when fibre is increased (Müller-Lissner, Kamm, Scarpignato, & Wald, 2005).
Other issues with fibre, and especially too much fibre, is that it increases the bulk or amount of volume of the stools. Fibre causes congestion or a traffic jam in your digestive tract... hence why increasing more fibre with an IBS or SIBO diagnosis will make your constipation so much worse. Fibre causes your gut microbiome to FERMENT the fibre-rich foods to cause GAS and BLOATING, which is a very common issue.
So much for the common vegan belief that meat causes constipation and fermentation, and that plant foods fix this. It doesn't.
Constipation can be reduced and even completely eliminated (pun intended!), but only by finding and fixing all the root causes in each person. I've fixed chronic constipation in some people who thought they had tried all the medications and supplements for 30-40 years without success. And everyone will be different. If constipation is an issue for you, or anyone you know, then I can help!
Better Health Channel. (2023). Dietary fibre. Retrieved 16th April 2023 from https://www.betterhealth.vic.gov.au/health/healthyliving/fibre-in-food
Ho, K-S., You Mei Tan, C., Muhd Ashik Mohd Daud, & Seow-Choen, F. (2012). Stopping or reducing dietary fiber intake reduces constipation and its associated symptoms. World Journal of Gastroenterology, 18 (33): 4593–4596. doi: 10.3748/wjg.v18.i33.4593
Müller-Lissner, S.A., Kamm, M.A., Scarpignato, C., & Wald, A. (2005). Myths and misconceptions about chronic constipation. American Journal of Gastroenterology, 100:232–242.
National Institutes of Health (NIH). (2023). Constipation (definition). Retrieved 16th April 2023 from https://www.niddk.nih.gov/health-information/digestive-diseases/constipation
Preston, D.M., & Lennard-Jones, J.E. (1986). Severe chronic constipation of young women: ‘idiopathic slow transit constipation’. Gut; 27:41–48