My grandmother once told me that whole corn was nothing but “roughage” – and she said this as if it were a bad thing. Perhaps her view was typical of her generation, one that lived through times of relative scarcity and prized calorie dense luxuries such as meat.
It turns out that fibre is essential for human health and the only place you can find it is in plants – fibre is what makes up the plants’ cell walls.
Fibre intake in Canada
It is nearly impossible to be deficient in protein while eating a varied diet with enough calories, but falling short of fibre requirements is not only possible, it’s the norm. The numbers are shocking: fewer than 3% of Canadians fail to get enough protein, while inadequate fibre intake is estimated at over 97%! That means fewer than 3 out of every 100 Canadians are getting the minimum recommended level of fibre. On average, Canadians get only half the recommended minimum daily intake.
This is a severe level of deficiency, especially when we consider that the recommended minimums of 25 grams of fibre per day for women and 38 grams for men are quite likely too low for vibrant health. Fibre deficiency could have serious health implications for you and your loved ones.
Prehistoric fibre intake
A study of fossilized feces from a prehistoric hunter-forager population reveals that the average daily consumption of fibre among men was 135 grams. Modern hunter-gatherer populations, such as the Hadza in Tanzania, consume 80-150 grams of fibre per day and have much better cardiovascular and metabolic health than the average Canadian. This suggestive link between fibre intake and health is well supported by scientific research – more on that below.
It would seem that humans likely evolved eating far more dietary fibre than the minimum recommended by Health Canada, a recommendation that very few Canadians manage to meet. Addressing this deficiency necessarily involves consuming more whole plant foods, and the benefits could be enormous.
Fibre and health
Dietary fibre has been linked to improved health in numerous studies. For example, a 2019 meta-analysis of over 200 studies found a significant link between increased fibre intake and lower all-cause mortality. The study is limited in that very little data exist for those consuming more than 30 grams of fibre a day, although the findings suggest that even greater health gains are likely as more fibre is consumed:
Observational data suggest a 15–30% decrease in all-cause and cardiovascular related mortality, and incidence of coronary heart disease, stroke incidence and mortality, type 2 diabetes, and colorectal cancer when comparing the highest dietary fibre consumers with the lowest consumers. Clinical trials show significantly lower bodyweight, systolic blood pressure, and total cholesterol when comparing higher with lower intakes of dietary fibre.
An even more comprehensive overview of the research on dietary fibre and health provides a similar summary of the health benefits of dietary fibre:
Dietary fiber intake provides many health benefits. A generous intake of dietary fiber reduces risk for developing the following diseases: coronary heart disease, stroke, hypertension, diabetes, obesity, and certain gastrointestinal disorders. Furthermore, increased consumption of dietary fiber improves serum lipid concentrations, lowers blood pressure, improves blood glucose control in diabetes, promotes regularity, aids in weight loss, and appears to improve immune function.
In addition, studies have linked intestinal cancers to fibre deficient diets.
In short, the available data suggest that eating more fibre rich foods reduces your risk of getting many serious health conditions and raises your odds of living a longer life.
Fibre supplements
It’s important to note that fibre alone is not wholly responsible for the better health outcomes mentioned above. The fibre intake in these studies came from eating whole plant foods, which also provide a plethora of other healthful components such as antioxidants, vitamins, phytonutrients, and minerals.
Fibre supplements are not able to confer many of the health benefits mentioned above, but they have some value. They can help improve serum lipoprotein values, lower blood pressure, improve blood glucose control for diabetic individuals, aid in weight loss, and improve regularity.
Of course, it would be much better to get these benefits and more by getting fibre directly from whole plant foods. Whole plant foods not only provide far greater health benefits, but eating more of them is also likely to displace less healthy foods from your diet, magnifying their beneficial effects even more.
Fibre and the microbiome
Our gut and colon are where the magic of fibre happens. Fibre contains zero calories, which may lead one to leap to some unfortunate conclusions about how vital it is to human health. The trick is that fibre isn’t food for us so much as it’s food for the bacteria living inside us. Fibre is a prebiotic, which creates the conditions for our gut microbiome to flourish.
The microbiome plays a significant role in modulating our immune system, which is why increasing dietary fibre has been shown to improve immune function.
The reason we reap so many health benefits from fibre is the short-chain-fatty-acids (SCFAs) which the bacteria in our colons produce when they chow down on dietary fibre. SCFAs are used throughout the body and have a host of functions including regulating gene expression, metabolism, inflammation, and disease. They also play a key role in eating behaviour, including appetite, and metabolic disorders.
This is a vibrant field of research which may help to explain what many epidemiological studies (e.g. The China Study, The Nurses’ Health Study, The Adventest Health Study) have been pointing at for decades: that plant-predominant diets are extremely healthy, and the move away from them in Westernized countries has led to an explosion of poor health outcomes.
Vegans take note
Even vegans are not necessarily getting enough fibre. Data from the EPIC-Oxford study show that vegans were consuming 25.9 (+/-9.3) grams of fibre per day compared to 21.6 (+/- 7.7) grams for vegetarians and 18.8 (+/-6.7) grams for meat-eaters. It’s clear that a large proportion of the vegans in this study were not meeting the minimum daily requirement for fibre.
With the proliferation of vegan processed foods, it’s easier than ever to construct an unhealthy vegan diet. It’s important to focus on whole plant foods to ensure you are getting enough fibre.
Meat-eaters have it worse
While some vegans could do better, meat-eaters who are not aware of healthful eating are in a far worse position. Those who include meat, dairy, and eggs in their diets and also eat processed foods are needlessly increasing their risks of negative health outcomes.
However, these meat-eaters can make the most progress with the least change. Substituting a meat heavy meal for one that’s loaded with fresh vegetables, beans, and grains (such as these) turns a meal with nearly zero fibre into one that could easily have 20 grams or more.
Fibre as a dietary goal
You can use fibre intake as an easy way to track how healthy your overall diet is. It’s hard to get 50-75 grams of fibre if you’re eating unhealthy foods and keeping your total calories in check. I would encourage you to track your intake for a week using a website like Cronometer and see where you fall. Then challenge yourself to get 5 more grams per day the following week. When you feel ready, challenge yourself to add another 5 grams per day. Continue doing this and within a few months you’ll have transformed your health for the better.
Focus on reducing your intake of processed foods, meat, dairy and eggs while increasing your intake of whole plant foods. This will tend to increase your fibre intake, decrease calorie density, and increase nutrient density. Tracking these changes with Cronometer can be invaluable since whole foods don’t come with nutrition facts labels.
Note that it can be important to increase your fibre intake slowly. If your body is not accustomed to eating a lot of fibre, it can cause gas and bloating at first. But trust me, as someone who eats around 80 grams of fibre a day, these issues go away once your microbiome adjusts to the change.
Foods to focus on
If you’re looking for a place to start, some of the best sources of dietary fibre are beans, legumes, berries, fruit, whole grains, starchy vegetables, and whole wheat pasta.
For example, my usual oatmeal breakfast (⅓ cup steel cut oats, ½ cup blueberries, ¼ cup cranberries, 1 banana, 1 apple, 1 Tbsp ground flax, and cinnamon) starts my day off with 20 grams of fibre, which is more than the average Canadian gets in their entire day.
Keep in mind that there are many different types of fibre, so consuming a variety of whole plant foods is key to reaping all the health benefits. In fact, the largest study of the human microbiome to date found that those who ate 30 or more different plant foods each week had more diverse microbiomes. So don’t rely on a single source of dietary fibre – eat a variety of plants to help optimize your health.
Photo by Alex Motoc on Unsplash
