How often do you hear:
“You need fibre from your fruits and veggies to prevent constipation!”
Or another popular claim: “You need fibre to feed your microbiome!”
Well if you decided to dig deeper, the truth might surprise you.
Here is a brilliant and humorous talk by esteemed professor Zoë Harcombe, researcher and author of a number of books questioning the reliability of public health guidelines.
1. Before the 18th century, when most people were free of the chronic diseases plaguing our society today, hardly anyone worried about fibre intake. Then came the 7th Day Adventists with their anti-meat agendas propagating that fibre would curb sexual lust . Next came Denis Burkitt, a surgeon who through his observation of African tribes eating much more fibre and not suffering diseases of western populations, proposed that diets low in fibre increase the risk of CHD, obesity, diabetes, dental caries, various vascular disorders and large bowel conditions such as cancer, appendicitis and diverticulosis . Cereal companies (many with origins from the 7th Day Adventists) quickly caught on to the trend as lack of fibre in diets was the perfect marketing tool for profits.
2. Well it turns out that fibre is not necessary for healthy bowel motions. In fact, removing all fibre from your diet might even improve constipation and any digestive problems you have!  If you think about it logically, why would we need to eat something that is undigestible and gives you digestive problems?
Pundits will say that it improves your microbiome diversity, feeding the ‘good bacteria’. But there is so much we still don’t know about the microbiome and whether we even need such diversity for good health (think of traditional populations like the Innuits that have perfect health on a very low fibre diet). But this can be a whole other blogpost.
3. The dietary guidelines for fibre are not evidence based. Kind of ‘plucked out of thin air’. Real evidence is interventional. This means conducting an experiment and measuring the results of tweaking certain variables in various groups. The gold standard is a double-blind randomized controlled trial. However, all the evidence we have is “a diarrhoea of epidemiology”. Basically, taking surveys and drawing associations, not CAUSATIONS.
This kind of evidence is very misleading as there are too many variables to control and the ‘healthy user bias’ – Healthier people are usually not just consciously eating well but engaging in many other healthy lifestyle habits like sleeping well, exercising and not smoking or drinking too much. Those eating less fibre may just be from lower income categories who struggle to make ends meet and have much larger concerns in their life than the amount of fibre they eat. They may tend to eat more processed food because it is cheap and convenient and/or they may lack the health knowledge .
4. Questionable claimed mechanisms:
“Fibre slows glucose absorption and improves insulin sensitivity”
– yes there is definitely evidence for this . However, you shouldn’t be eating that much glucose in the first place! Sugar is the enemy that’s been linked to almost every chronic disease plaguing mankind. Go low carb and you’ll improve your health and eliminate the need for fibre.
“Fibre inhibits cholesterol synthesis and reduces serum cholesterol levels”
– its not really the fibre that does this but rather the sterols in plants
“Fibre promotes weight loss by regulating energy intake”
– this statement is misleading as the main study that drew that conclusion compared whole foods like apples being more satiating than apple juice that does not have fibre but still contain the same amount of carbohydrates . So the case if more for whole foods that contain fibre makes you more satiated and therefore promotes weight loss because you eat less!
“Consumption of fibre, especially from vegetables, is
associated with higher micronutrient intakes, promoting health and decreasing
risks of chronic disease”
– this argument is not a case for Fibre per se, but rather for foods that contain these micronutrients that just happens to also contain fibre. However, animal foods have much higher amounts of micronutrients that are also more bioavailable than plant foods (meaning we can absorb them better)
“Fibre decreases transit time, decreasing time of contact between carcinogenic foods and the lining of the colorectum”
– yes that is true but
1) to avoid colon cancer in the first place, why are you eating carcinogenic foods?
2) if you are accelerating your nutrients’ transit time in the colon, then there is less time for nutrient absorption, which is worrying.
3) If an empty bowel is the best thing, then fasting is the solution, not accelerating transit time
“Fibre alters your intestinal microbiota and function, feeding the good bacteria”
– The factors that creates optimal microbiome is much more than fibre. It starts at birth (vaginal vs C-section), being breastfed, not taking antibiotics or medications that alter you microbiome like antacids, not eating processed/junk food or foods sprayed with pesticides and eating a wholesome diet. And what about foods that don’t contain fibre but still are very good for gut health like fermented yogurt, kefir and miso? What about animals that don’t eat fibre but still have a perfectly healthy microbiome?
– In short, there is really so much we don’t know about the microbiome at present. Here is an interesting paper comparing the microbiome across many species of mammals .
“In humans, adopting a high-protein diet increases the abundance of bile-tolerant bacteria, whereas a plant-based diet enriches microbial taxa that specialize in carbohydrate fermentation (David et al. 2014; O’Keefe et al. 2015), paralleling the differences observed in gut microbiomes of hunter gathers vs. humans in industrialized societies (Rampelli et al. 2015; Morton et al. 2015a).” 
So, is a high-protein (meat) hunter-gatherer microbiome composition better than a plant-based industrialized human’s microbiome composition? Given our higher rates of chronic diseases, it seems to suggest so. And yes, we can debate on the fibre consumption of our Paleolithic ancestors but we’ll leave that for another long blog post 😉
Dietary guidelines for fibre intake have been tainted with personal, corporate and financial agendas. Ditto to the many claimed benefits of fibre. There is really no physiological NEED for fibre to maintain healthy bowel motions. In fact, many people have found that eliminating fibre can improve all kinds of digestive problems, including constipation.
I am personally running a self-experiment to test this theory that fibre is unnecessary.
I did this because I suspected that I was having too much fibre following The Wahls protocol of consuming 9-11 servings of veggies daily! My stools were literally green and big (like the hulk 🥦) and so painful to pass (excruciating! 😭) . There was also fresh blood each time I wiped – indicating some tissue tearing.
It was so bad that I dreaded going to the toilet to do my number 2s for weeks!
Today is day 25 and I can safely assure you that those painful poops have resolved!
It’s such a relief not having to worry about painful poop. Another bonus observation is I hardly fart anymore! When I do, they are almost odourless. 🌬✨
One thing to note is that I still had some constipation issues – pooping about once every 2 days. I found out that this was because my body doesn’t produce enough bile. This was evident in the colour of my stools which were pale gray to pale yellow ever since I cut out the plants.
Eventually I solved this problem by eating 4 raw egg yolks (without the whites) a day! This is because egg yolks are one of the richest sources of choline with 147 mg per large egg.  Adults need 425 (female) to 550 mg/day and many are deficient.
Choline is essential for making enough bile to digest fats and form good stools as well as synthesizing healthy cell membranes for overall brain and body health.
This is an excellent article about the Incredible, Edible Egg Yolk! https://chrismasterjohnphd.com/blog/2005/07/01/the-incredible-edible-egg-yolk/
So … what do you think about fibre now?
and have you had any fibrous problems lately? 😉
Keep questioning your assumptions
- Ellen G. White. Counsels on Diet and Foods.
- Cummings, J. H., & Engineer, A. (2018). Denis Burkitt and the origins of the dietary fibre hypothesis. Nutrition research reviews, 31(1), 1-15.
- Ho, K. S., Tan, C. Y., Mohd Daud, M. A., & 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
- The Problem With Epidemiological Studies – https://www.diagnosisdiet.com/epidemilogical-studies/
- Nicola Veronese, Marco Solmi, Maria Gabriella Caruso, Gianluigi Giannelli, Alberto R Osella, Evangelos Evangelou, Stefania Maggi, Luigi Fontana, Brendon Stubbs, Ioanna Tzoulaki, Dietary fiber and health outcomes: an umbrella review of systematic reviews and meta-analyses, The American Journal of Clinical Nutrition, Volume 107, Issue 3, March 2018, Pages 436–444, https://doi.org/10.1093/ajcn/nqx082
- James W Anderson, Pat Baird, Richard H Davis, Stefanie Ferreri, Mary Knudtson, Ashraf Koraym, Valerie Waters, Christine L Williams, Health benefits of dietary fiber, Nutrition Reviews, Volume 67, Issue 4, 1 April 2009, Pages 188–205, https://doi.org/10.1111/j.1753-4887.2009.00189.x
- Nishida, A. H., & Ochman, H. (2018). Rates of gut microbiome divergence in mammals. Molecular ecology, 27(8), 1884–1897. doi:10.1111/mec.14473
- Sources of choline – Choline Fact Sheet for Health professionals. National Institute of Health.
- The Incredible, Edible Egg Yolk! https://chrismasterjohnphd.com/blog/2005/07/01/the-incredible-edible-egg-yolk/