Do you eat enough fibre?
The recommended intake for men is 30g and 25g for women per day, but data indicates many Australians don’t hit this target.
Let’s take a look at why this may be a problem for our health.
What is Fibre?
Fibre, an indigestible carbohydrate, has been found to significantly reduce the risk of developing a range of diseases including colon cancer, gastrointestinal disease, constipation, haemorrhoids, gastroesophageal reflux, obesity, stroke and hypertension.
Fibre and Colon Cancer
In the early 1970’s, lower rates of colon cancer were noted in communities who consumed diets high in fibre. There are a number of mechanisms by which this occurs, but one of interest is that the increased intake of fibre leads to a dilution of faecal carcinogens meaning less opportunity for them to wreak havoc. In addition, fibre produces short-chain fatty acids, some of which have anti-carcinogenic properties.
Mounting evidence demonstrates clear links between increased fibre and reduced risk of colon cancer.
Not only that, but there have been suggestions that a high fibre diet can be protective in communities who eat high quantities of processed meat too. We are constantly bombarded with information that processed meat is “bad” for us, but the data is indicating that fibre can be protective even if we do occasionally eat processed foods.
The average fibre intake for communities back in the 1970’s was over 50g of fibre, so perhaps we should take note.
Fibre and Acid Reflux
Low dietary fibre intake is regularly associated with decreased stomach and gut motility and delayed emptying, which can contribute to the risk of gastroesophageal reflux and its associated disease (GERD.)
It is thought that dietary fibre binds to nitric oxide and diminishes its negative influence on lower esophageal sphincter pressure.
Fibre is also thought to decrease gastric acidity, lowering the number of refluxes, and reducing their damaging capacity.
The common treatments for GERD include suppression of gastric acid secretion, but this can be problematic. The use of proton pump inhibitors is associated with a decrease in bacterial richness in the gut microbiome and quite often pathogenic bacteria are increased. This imbalance, known as gut dysbiosis, has been associated with a range of health issues including, not surprisingly, intestinal disorders like irritable bowel syndrome and coeliac disease along with extra-intestinal disease such as asthma, allergy, metabolic syndrome, cardiovascular disease and obesity.
When the intake of dietary fibre decreases acid reflux episodes, it is certainly worth considering in light of the side effects noted in other treatments.
Fibre and Cognitive Health
Whilst fibre is indigestible, some dietary fibres can be fermented in the colon. The result of this is the production of short-chain fatty acids.
Acetate, butyrate, and propionate are these short-chain fatty acids (SCFAs) and have a long-known role in the colon’s energy supply, the regulation of immune function, the maintenance of the gut-barrier and evidence now suggests a physiological effect on the brain.
Short-chain fatty acids have been known to modify neurotransmitter precursors in the gut, specifically GABA, serotonin, dopamine, and noradrenaline. Not only that, but butyrate possesses an anti-depressant like effect.
Levels of SCFAs are routinely decreased in depression cases.
SCFAs have also been seen to interfere with the assembly of neurotoxins which are responsible for synapse dysfunction (which occurs in neurodegeneration). A healthy population of SCFAs is therefore deemed protective in developing cognitive disorders.
What’s particularly interesting is that intestinal imbalance does appear to play a role in several cognitive disorders, fibre however, can play a pivotal role in tackling intestinal imbalance. So eat fibre to support your brain health.
Is there a dark side to fibre?
Whilst fibre is deemed protective and beneficial in a range of health issues, the very foods that are high in fibre like cereals, pasta, leafy green vegetables, nuts, seeds, peas, beans and pulses also contain phytic acid. It has been demonstrated that an increase in fibre inevitably increases phytate. This is relevant in mineral balance. Phytic acid has a strong binding affinity to minerals such as calcium, iron and zinc, preventing their absorption.
However, this very binding has been seen to be protective in colon cancer. By binding copper and iron which could initiate oxidation reactions, phytate may protect intestinal cells from exposure and possible mutation. Interestingly, Vitamin C has been seen to counter phytate inhibition, so you could increase vitamin C intake alongside your fibre filled meals!
Fibre rich foods also contain lectins which have received much attention for their role in disease. Of particular interest is a potential role in autoimmune disease. Whilst there are arguments on both sides of the coin, most evidence is pointing to certain conditions like rheumatoid arthritis as being a sequelae of infections. Where some individuals are protected against the effects of lectins, some can have their protective molecules stripped off by enzymes present in various viruses and bacteria.
It seems there is clear evidence that fibre can be protective in a range of diseases and whilst fibre rich foods can be high in phytate and lectins, these factors can be managed and data suggests that the benefits outweigh the risk for generally healthy individuals. So, how are you hitting your fibre target today?
