Don’t Eat The Vegetables!
Whoever managed to convince the world that consuming bucket loads of fiber – from raw vegetables, cereal grains, beans, nuts, seeds and the like – was a good idea for health generally and for digestion more specifically, certainly pulled a fast one.
Wait a minute. Might it have been the same people who brought us the polyunsaturated seed oils and fish oils (PUFAs). The same people who marketed and misrepresented those products as ‘heart healthy’ and protective, and explained away increases in disease to be the result of saturated fat, cholesterol and sugar consumption.
Who is behind these kinds of advertisements, government findings, recommendations and official guidelines. Are they ‘scientific’? Is there a common thread binding them together? Is the solution as obvious as ‘just follow the money’?
“Lack of fiber in the diet was first postulated in 1971 as the cause of diseases such as diverticulosis, hemorrhoids and colorectal cancer. Since then, partly due to widespread media publicity, it is now widely accepted that dietary fiber is a necessary component of a healthy diet and is required for normal bowel movement.”
In the real world, the answer to the question regarding whether eating more fiber (or less fiber) is beneficial, or harmful, is not always as simple as yes or no.
In one study, 63 patients with so called ‘idiopathic’ (i.e ‘we have no explanation’) constipation – with symptoms including ‘constipation, abdominal distension, pain or bloating, difficulty in evacuation with or without symptoms of rectal bleeding’ – enrolled to examine the effects of removing all dietary fiber, ‘including vegetables, cereals, fruits, wholemeal bread and brown rice’ on bowel movement regularity and other related issues.
“They were to continue their normal quantities of carbohydrates and proteins. Sieved fruit juices and clear vegetable soups were allowed…After 2 wk, patients were asked to continue on with as little fiber in their diet as they were comfortable with for the long term.”
The results at the 6 month follow-up showed a significant improvement in regularity, relative to the reduction in fiber.
On top of this, all other related symptoms improved relative to fiber reduction, and only resolved completely for those in the ‘no-fiber’ group. The conclusion of the study was that the ‘previous strongly-held belief about the application of dietary fiber to help constipation is but a myth.’
So are there any biologically valid explanations for all the confusion regarding the role of fiber in relation to healthy digestion and health in general?
Like many aspects of diet and metabolism, this is not a black and white problem, there is no one answer to solve all issues, and an appreciation of context is crucial for a deeper understanding.
Whilst it is true that in many circumstances (some which I will discuss further on) fiber can be very helpful (some kinds more than others), it is also true that consumption of large amounts (and the wrong kinds) of fiber isn’t always a good idea, and can in fact end up being an important factor interfering with proper function, fueling disease.
“…incidence of diverticulosis and complications of diverticular disease have been increasing in the West despite increase in dietary fiber intake. This is probably related to the massive gaseous build up associated with a high dietary fiber intake.”
“The aim of this study was to assess the effect of coarse wheat bran on specific bowel function parameters and symptoms in patients with irritable bowel syndrome (IBS)…The addition of coarse wheat bran to the diet increased…stool wet weight in this group of IBS patients, but no evidence was obtained that such treatment was of benefit to these patients…”
Popular foods recommended for their fiber content, often have in them harmful anti-nutritional, allergenic and sometimes even carcinogenic substances, which can interfere with digestive function via suppression of metabolism, and the reduction in effectiveness of digestive enzymes.
“The anti-nutritional factors can be defined as those substances generated in natural food substances by the normal metabolism of species and by different mechanisms (e.g. inactivation of some nutrients, diminution of the digestive process or metabolic utilization of feed) which exert effects contrary to optimum nutrition.”
But it is also fiber itself which (especially when taken in excess) is often not helpful, and can end up causing issues.
“…more recently, better designed longitudinal studies have not supported a correlation between fiber and prevention of colorectal cancer…study of 45 491 women in the Breast Cancer Detection Demonstration Project over 8.5 years also found little evidence that dietary fiber intake lowers the risk of colorectal cancer.”
“We conducted a randomized trial to determine whether dietary supplementation with wheat-bran fiber reduces the rate of recurrence of colorectal adenomas…a dietary supplement of wheat-bran fiber does not protect against recurrent colorectal adenomas.”
“By increasing fiber intake, stool frequency and faecal weight will be correspondingly increased… The formation of large amounts of faecal material can actually have a detrimental effect on the patient. Faeces that is bulky and hard is more difficult to evacuate in a patient with a pre-existing evacuatory problem.”
“Fiber is not helpful in patients who have defaecation disorders. A recent study…suggests that this condition is more frequent than previously thought…there is little physiological basis for increasing fiber intake and thus bulkiness of the stool in constipating and defaecatory disorders.”
Fibers found in foods like beans, cereal grains, nuts and under cooked vegetables – even fruits – cannot be digested by humans, and as such often end up being left for bacteria to feed on. This can be especially problematic when stress is high and metabolism is compromised.
The overgrowth of bacteria throughout the intestine and the resultant increase in endotoxin release (occurring increasingly when energy systems are suppressed) – promotes a rise in inflammatory stress substances (such as serotonin, estrogen and nitric oxide) – which then further suppress thyroid and energy system function, and interfere with digestion.
Improving thyroid energy metabolism has been shown to improve digestive function, and as such, some of the perceived beneficial effects of fiber intake may arise as an inadvertent consequence of increased energy intake (fueling metabolism), rather than from the direct effect of fiber on intestinal motility.
“Hypothyroidism can cause constipation…A diet poor in fiber should not be assumed to be the cause of chronic constipation. Some patients may be helped by a fiber-rich diet but many patients with more severe constipation get worse symptoms when increasing dietary fiber intake.”
“Constipated subjects reported consuming fewer meals per day compared with control subjects and a tendency to consume fewer calories. There were no differences between groups on fiber or fluid intake or any of the other dietary parameters. However, slow colonic transit was significantly related to low caloric intake…and to psychological symptoms of somatization, obsessive-compulsiveness, depression, anxiety…”
As digestion is slowed there is often a build up of toxins, partly because of a reduction in the speed of evacuation, leaving waste materials in the system for longer than optimal periods of time.
More time is then left for bacteria to feed on and ferment undigested fiber and other things, allowing bacteria to grow in number and move further up the intestine, promoting what can eventually become a vicious circle driven by endotoxin and a number of related inflammatory substances, including serotonin, nitric oxide and lactic acid.
These substances of stress and inflammation can then go on to exacerbate the digestive and other metabolic issues, that the consumption of increased fiber is being touted as protective against.
“Intestinal inflammation alters the contractile activity of intestinal smooth muscle. Motility disorders of the gastrointestinal tract are…often associated with severe…inflammation. In addition, the motility disorders secondarily induce abnormal growth of the intestinal flora, and the resulting disturbance of this flora aggravates the pathogenesis of mucosal inflammation. This in turn aggravates the intestinal dysmotility; i.e., it is an inflammatory spiral.”
“Altered gastrointestinal (GI) motility is seen in many pathological conditions. Reduced motility is one of the risk factors for development of a small intestinal bacterial overgrowth (SIBO). Hypothyroidism is associated with altered GI motility.”
The slowing of digestion plays a big part in the re-absorption of estrogen (as well as many other harmful anti-thyroid substances) into the system, as a result of interference with proper elimination, and this can then end up playing a big part in the promotion of worsening inflammatory conditions, and greater suppression of digestion.
Exposure to chronically high levels of estrogen is powerfully anti-thyroid, and is a common factor driving a downward spiraling vicious circle of stress and inflammatory disease.
Removal of excess estrogen is often proposed to be one of the potentially health promoting benefits of the consumption of more fiber.
“Experimental and observational data provide compelling biological evidence that frequent bowel motility is associated with increased excretion of estrogen in the stool and lower serum estrogen levels…we observed no association between bowel frequency and intakes of fiber-containing laxatives or dietary fiber.”
The bulking nature of fiber can fuel estrogen related issues, not simply by feeding bacterial overgrowth, but also because of factors such as stool size build-up, which can slow movement and interfere with evacuation.
Consuming saturated fat (butter or coconut oil for instance) with fiber, is one way to reduce bacterial interaction and possibly help even potentially harmful fibers to assist with movement and waste removal.
“The role of dietary fiber in constipation is analogous to cars in traffic congestion. The only way to alleviate slow traffic would be to decrease the number of cars and to evacuate the remaining cars quickly. Should we add more cars, the congestion would only be worsened.”
Too much fiber intake can increase stool size to the point of stretching and irritating intestinal tissue, promoting further inflammation and the increased release of metabolically suppressive substances such as serotonin and nitric oxide.
“Serotonin…can cause abdominal pain and discomfort, satiety, or nausea…promote intestinal inflammation…can have extra-alimentary actions such as influencing bone densitity and contributing to allergic airway inflammation.”
Digestive inhibition and the related rise in secretion of stress substances, has been shown to interfere with blood sugar regulation, and this can then lead to an increase in the release of the polyunsaturated free fatty acids from storage, which (on top of the PUFA content found in the fibrous foods) plays a significant role in the further suppression of proper digestive function.
Even though fiber is popularly promoted as something which can protect against the progression of diabetes symptoms, to the extent that it can feed bacteria and cause a rise in bacterial endotoxin, estrogen, nitric oxide, serotonin and lactic acid (all substances which suppress thyroid and promote diabetes), this seems like a risky approach.
Although there are some fibers, such as in raw carrot for example, which are safer and can be very beneficial due to anti-bacterial properties, reliance on fiber in general for improved bowel frequency, often ends end up being reliance upon a kind of irritation or toxin initiated flushing effect.
Alternatively, many true health benefits arise as a result of real improvement in bowel motility due to an improvement in metabolic function and a consequent increase in digestive speed and efficiency.
In circumstances where metabolic function is damaged, removal of fiber from the diet might at first slow things down, due to the irritation and stimulation effect having been removed. This can potentially (at least temporarily) lead to a worsening of symptoms and metabolic health issues.
Therapeutic use of the safer fibers (as well as a few things with binding or laxative effects) can be particularly useful during this ‘transitional’ period, or just generally in order to help clean the intestines and remove toxic materials when there isn’t regularity.
But it’s important to keep in mind the potential for foods (being pushed as a solution to issues of digestive slowing and constipation), to cause an increase in the substances like serotonin, responsible for worsening of bowel inflammation related issues. This can result in chronic diarrhea, or fluctuations between the two extremes of diarrhea and constipation common with IBS and other conditions.
“…the 5-HT [serotonin] level has been shown to be altered in experimental intestinal inflammation and in IBD patients, and high levels of 5-HT have also been described in several inflammatory and diarrheal conditions.”
There isn’t a ‘one size fits all’ solution to metabolic issues related to digestion, and so from one perspective the use of fiber for intestinal stimulation, can be potentially beneficial, at least to the extent that it can help move things along and promote an overall improvement in elimination and detoxification.
This is probably more likely if the fiber being ingested has anti-microbial properties (so that it doesn’t have the same potential to promote bacterial overgrowth), and comes in foods which have less of the anti-thyroid digestion interfering substances inside.
Apart from the fiber in raw carrots and bamboo shoots and some other things, fiber from well cooked potatoes has been shown to be reasonably safe for those who can digest them well enough.
“…present study provided evidence of quality difference of fiber types and proved that the insoluble fiber from bamboo shoots is the most effective in suppressing high-fat diet induced obesity and accompanied changes in metabolism.”
When metabolism and digestion are already damaged however, even foods with the safest ingredients and fibers can potentially worsen existing issues, if consumed in excessive quantities.
“Eighty percent of patients with slow transit and 63% of patients with a disorder of defecation did not respond to dietary fiber treatment…Slow GI transit and/or a disorder of defecation may explain a poor outcome of dietary fiber therapy in patients with chronic constipation.”
So what could possibly be the motivation behind the vast number of glowingly positive endorsements advocating the use of fiber as a healthy digestion promoting technique?
It certainly is a clever way to promote the healthiness of products that provide a large portion of the profits for powerful industries with economic and political importance.
There is also the issue of creating new industries out of what were formerly waste materials from existing production. In a sense, turning people into something like human rubbish tips and making them pay for the privilege.
There are many possible explanations, and they often go beyond pure profit motive alone. There is no doubt in my mind that the highly contextual nature of issues of metabolism, makes it difficult to grasp the idea that fiber can be both a good thing and a bad thing depending on changing circumstances and conditions.
A potentially effective approach for dealing with digestive issues – including constipation – is one that experiments with a simple diet, limiting fiber, whilst gradually improving metabolism with sufficient protein from milk, cheese and gelatin, and plenty of sugar from cooked or ripe juicy low fiber sweet fruits, fruit juice, honey and white sugar.
Some other things that can help improve digestion include thyroid hormone, pregnenolone, progesterone, activated charcoal, cyproheptidine, certain antibiotics, coconut oil, coffee, cascara, aspirin and other anti-inflammatory pro-metabolic substances.
Using fiber (especially that which has inbuilt anti-bacterial properties) in combination with the antimicrobial saturated fats (or using milk or cheese for the additional calcium which can also help protect against bacteria) in order to improve motility when necessary, is likely to be helpful.
It’s impossible to come up with one solution for digestion issues for all people, based on a set of rules or a specific protocol that must be followed. Experimentation with different combinations of foods (and other pro-metabolic things) makes sense, and what will work depends on individual metabolic conditions. However because of misleading guidelines masquerading as scientific facts, it often ends up being a shot in the dark.
Even under ‘ideal’ conditions, the question regarding whether fiber is ‘good’ or ‘bad’ cannot be conclusively answered, because of different kinds of fiber and other variables or changing circumstances. Things that help for a while may no longer be necessary when metabolism changes.
Yes, certain types of fiber are more helpful than others – like the anti-microbial fiber in raw carrots and bamboo shoots, or the anti-estrogenic substances in well cooked mushrooms – but healing takes time, and we do not live in a vacuum.
Unfortunately there is a very powerful belief system surrounding the idea that fiber is something we need a lot of for our digestive system to function properly, and this can end up being a hindrance for recovery or the maintenance of health.
“…what we have all been made to believe about fiber needs a second look. We often choose to believe a lie, as a lie repeated often enough by enough people becomes accepted as the truth. We urge clinicians to keep an open mind.”
My mother isn’t the only person who has been exposed to decades worth of ‘roughage indoctrination’, and hidden inside it are elements of truth which can make the idea far more difficult to let go of, even when it no longer serves you.
It’s true that unicorns are probably mythological creatures, but I’ve heard that we really do live in a world where it’s possible to fart rainbows.
See more here
Physiological modulation of intestinal motility by enteric dopaminergic neurons and the D2 receptor: analysis of dopamine receptor expression, location, development, and function in wild-type and knock-out mice.
Meme: by me