Fibre: Not Essential, Not a Nutrient.
I wrote a controversial, but popular article on LinkedIn about fibre a while ago. Here is a more thorough exploration of fibre - apparently the healthiest nutrient for human consumption! Mainstream guidelines, Nutritionists and Gastroenterologists recommend a high fibre diet as the cure for every disease. It took me a decade of suffering with crippling IBS (and other things) and severe constipation to question fibre. I never thought that fruits and vegetables could be bad for me! I used to eat ALOT of fibre in every single meal. My plate was often just boiled vegetables with a bit of salt, and some lentils - it would fill me up for a few hours, but really it was a distraction from my nutrient deficient vegan/vegetarian diet & eating disorder. What is Fibre?
There are various types of carbohydrates - but carbohydrates are essentially a chain of sugar molecules.
There are various types of simple sugar molecules - glucose, fructose, galactose.
These simple sugar molecules combine in various combinations to produce 'chains' or 'polymers'. If 2 sugars combine in a certain combination, they can form sugars. For example, lactose in milk or sucrose in honey & table sugar.
Starches are a large chain of sugar molecules. Think lentils, grains, starchy vegetables.
Fibre is a chain of sugar molecules that we cannot digest.
It is a carbohydrate. It is one of 3 macronutrients - protein, fat and carbohydrate. Only protein and fat are essential in the human diet. [See my article - Nutrition Basics]
Why Humans are not meant to eat a lot of fibre: An evolutionary perspective, and comparison between various animals.
The size, shape and distribution of various parts of the gut tells us the story of evolution, and about what kind of diet shaped the evolution of that particular animal.
So, I have mentioned that we cannot digest fibre. There is no mechanism in the human gut to digest fibre. There are animals that eat a lot of fibre - herbivores and even our cousins - chimpanzees and gorillas, but even they do not digest it, their gut bacteria do. They then absorb the fats produced from fibre fermentation, and eat the dead bacteria which is rich in protein.
There are 3 types of guts in the animal kingdom:
1) Ruminants/Foregut Fermenters: Eat only fibre, they have 4 stomachs EG: Cows.
2) Hindgut Fermenters: Have a large colon and fermentation vat EG: Horse
3) Monogastric animals: Intestine is small in size, Most of the digestion and absorption occurs in stomach & small intestine. EG: Humans, Carnivores
Look at the diagram above, and you will notice that the human gut is very similar to that of our best friends - dogs! And dogs are carnivores.
Let's look into this further:
➡ Humans have a very acidic stomach. This is similar to that of carnivores such as cats or dogs, and is designed to digest protein rich foods with the help of digestive enzymes (meat)
➡ Humans absorb most of the nutrients in the small intestine. This is predominantly high quality proteins, fats, vitamins and minerals. All of which comes from animal foods.
➡ Fibre is undigested and goes to the colon, where it gets fermented by our gut microbiome to produce SCFA (Short Chain Fatty Acids) - this can have benefits for gut health. The point is that our colon is TINY and incapable of excess fermentation. This is why eating a lot of fiber causes bloating and gas. We are not designed to eat that much of it. It is better to either follow a ketogenic diet that promotes SCFA production, or eat healthy animal fat.
➡ Cows have 4 stomachs, and a lot of bacteria in their gut that ferment this fibre into fats. Cows also absorb protein from the dead bacteria. Cows basically end up absorbing protein and fat. Humans are unable to absorb protein from dead bacteria in the gut. Besides, our colon is tiny and the amount of fat we get from fermenting fibre is very small.
Fibre worsens constipation by bulking up your stools. There is no evidence that fibre cures constipation
➡ The idea is that it bulks up the stools, therefore treats constipation.
➡ You do not want bulky stools if you are constipated - that will make things WORSE.
➡ BULKY STOOLS = LARGER STOOLS = HARDER TO PASS through the thin tube (the intestine). You want small, easy to pass stools. NOT bulky stool.
➡ This is an idea and a belief that is NOT tested by good quality scientific studies. There is only ONE study on fiber and constipation - it showed that a no-fiber diet 'cured' constipation. [1]
Fibre is not appropriate for people with gastroenterology issues - IBS, IBD, Crohn's Disease, etc.
Fibre is not recommended in these conditions as it can bulk up the stools, and cause something called 'obstruction' - it gets stuck in the colon - similar to constipation.
It also gets fermented by the gut bacteria and produces which can cause bloating and discomfort. I'm sure you've felt that when eating raw kale, or excess amount of lentils.
Potential benefits and claims about fibre.
➡ It promotes gut microbiome diversity. Yes, it can encourage gut microbiome diversity - but what does that mean? Does it translate to reduced risk of cancer, diabetes etc? Most of the gut microbiome science is NEW and conducted by supplement companies selling probiotics. They don't take into consideration that the gut also contains fungi, viruses, worms, etc. Why only bacteria? How do they interact with each other?
➡ The Short Chain Fatty Acids from fermentation of fibre - just eat good quality fat like ghee! It will do wonders for the gut.
➡ Reduction of cholesterol. Yes, it can reduce LDL in certain individuals - I have seen mixed results. But that does not mean anything, as I have discussed in previous articles. The amount of cholesterol esters present within all the LDL particles are not not predictive of heart disease. [I have written a lot of articles about it]
➡ Fibre makes you feel full, so you end up eating less gunk. TRUE. It also stimulates the GLP-1 receptor. I personally feel much more satiated eating protein and fat, without the bloating.
➡ Polyphenols and Other Biochemically Active substances: This is something that I believe has benefits. Herbs and spices are an excellent source of polyphenols and bioactive compounds such as curcumin (turmeric), catechin (green tea), sulpharophanes (broccoli sprouts). These chemical substances stimulate a mild inflammatory response, instigating your immune system and making you stronger. It's a bit similar to vaccines that give you protection against a pathogen. Or, like a chicken pox infection that makes your cells remember them, and then you get immune to it for life. How cool is it that our cells have memory? Every cell in our body is sentient. [4] Anyway, this has to do with the chemicals themselves, not fibre.
➡ Studies on people who consume more fibre show that they live longer and are healthier. This should be obvious - it means they're eating whole foods such as fruits and vegetables rather than McDonald's and KFC!
Take away for daily life:
➡ Fibre is not a nutrient.
➡ Fibre is not digested in the gut of any animal. Fat and Protein in the human diet should come from animal foods, not from fibre.
➡ Fibre is not essential for human nutrition , but it can have benefits in context of a whole foods diet.
➡ There is no good evidence that fibre prevents colon cancer.
➡ Excess Fibre can cause constipation and worsen gut issues.
➡ If you must eat fibre, cook the vegetables properly to break it down into digestible bits. Eat seasonal and locally available vegetables. Find your fibre threshold. It might vary from individual to individual. A little bit of fibre might have some benefit, but you certainly don't need to stuff yourself with it like I used to.
➡ Eat animal fat. This will stimulate bile production, promote gut health and regular bowel movements. It also nourishes the gut lining and the microbiome. It is essential for absorbing fat soluble vitamins A D3 E K2.
➡ Eat fermented foods. Get dirty in the soil to enhance your microbiome.
References/Further reading:
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