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Could you have a fibre deficiency? In this article learn about what fibre is and why you need it. Find out how I make sure I get more of it into my daily diet and how you can too.
“No western disease has been reported to be other than rare or uncommon in communities subsisting largely on foods rich in starch and fibre and low in fat, salt and sugar.¹”
Denis P Burkitt, MD
Back in medical school we had a surgical consultant who drummed into us the value of a high fibre diet for the prevention of many of the diseases we were seeing on his ward rounds – from diverticulitis to haemorrhoids to colorectal cancer. He told us about the rising incidence of diverticular disease for example, among urban Africans who were replacing high fibre maize meal and whole meal bread with refined low fibre, sifted, maize flour and white bread common to the Westernised diet.² At the time there was even good evidence that a diet low in fibre was associated with type 2 diabetes.
Now, decades later, we have a much greater understanding as to why fibre is so crucial for our overall health. Fibre is food for our gut microbiome. As we are beginning to appreciate more and more we are only as healthy as the health of our gut flora.
What exactly is fibre?
Fibre is the undigestible part of carbohydrates from plants and traditionally has been thought of as either soluble or insoluble depending on whether it dissolves in water. Most naturally occurring high fibre foods contain variable amounts of both types. Resistant starch (in other words, starch resistant to digestion) is another component of dietary fibre, of the soluble type.
Foods high in resistant starch include oats, rice, beans, potatoes and green bananas. Cooking destroys most resistant starches but you can recapture the resistant starch by allowing the food to cool down and eat it cold.
Soluble fibre is more readily fermented by our gut microbiota and insoluble fibre absorbs water and helps move food and waste through the digestive system, promoting regular bowel movements. Now that we are beginning to understand just how fibre and our gut flora interact it may be more useful to think of fibre as being fermentable or non-fermentable.
There are other important natural compounds of course that are found together with fibre in the whole food package. This is why ideally, we should be eating plants foods in their whole or unrefined form or as close as possible. Don’t rely only on fibre supplements, which don’t appear to have the same positive effects anyway. Remember, there is no fibre in meat or dairy products.
What are prebiotics?
Prebiotics are a type of soluble fibre selectively used by those beneficial gut bacteria that confer a health benefit, including those commonly used as probiotics – Lactobacillus and Bifidobacterium. Some common prebiotics include banana, peas, garlic, leeks, onions, asparagus, eggplant, legumes and wholegrains.
How much fibre do I need?
Current recommendations for dietary fibre for adults are between 25g to 30g/day. Greater benefits are seen with more than 40-45g/day – approximately triple what is found in the usual Western diet which on average only contains 14-18g/day.³ A deficiency of fibre is probably the most widespread nutrient deficiency in those eating a typical Western Diet. No upper level of intake is set as a diet high in fibre will not produce substantial adverse effects when part of a healthy diet. (In fact we were probably designed to get around 100g per day based on modern-day, isolated, hunter-gatherer tribes⁴.
But of course, if you’re not used to eating a high fibre diet, you will need to add fibre slowly. If you don’t have enough good gut bacteria to begin with then too much fibre can cause intestinal discomfort. It won’t take long though for the good bacteria to start flourishing and once they do you will be able to tolerate much more fibre. Then try to maintain a high fibre diet because the bacteria will die back off if you stop eating it. You will also need to drink more water than you might usually do.
What will fibre do for me?
Besides keeping you regular and being the most effective treatment for constipation (and as a result preventing conditions like haemorrhoids, hiatus hernia and diverticulosis (outpouchings from the wall of the colon from straining at the toilet), fibre binds to toxins like heavy metals as well as excess cholesterol and oestrogen that the body is trying to get rid of and flushes them out. Fibre also protects the intestinal barrier and overall health of your colon. Soluble fibre in particular, (prebiotics), promote bacterial growth and from the fibre, bacteria produce short chain fatty acids which are an important energy source for the cells lining the colon. These short chain fatty acids also acidify the environment making it more difficult for harmful bacteria to survive, suppress chronic inflammation both in the bowel and systemically and have a modulating or positive stimulating effect on the immune system. They pass into the bloodstream and have far reaching effects throughout the body.⁵
By increasing your fibre intake you can expect:
• An improvement in insulin sensitivity and reduced risk of developing type 2 diabetes
• Protection against inflammatory bowel disease and diverticulitis
• Reduction in total cholesterol levels
• Reduced body weight, abdominal adiposity and fatty liver
You will also decrease
• chronic inflammation
• your risk of high systolic blood pressure, heart disease and death from heart disease
• depression and anxiety
• your risk of colorectal cancer and breast cancer
and your risk of death from all causes
Which foods are high in fibre⁶?
Legumes, wholegrains, nuts and seeds, vegetables, fruit, specifically:
Raspberries and pears, green peas and broccoli, barley and oats, bran flakes and quinoa,
Fibre superstars are legumes like split peas, lentils, black beans, chia seeds, nuts and seeds.
Practical ways to increase your fibre intake:
I begin my day with a high fibre breakfast which always has as its base oats with berries. A serving of each will give me close to 10g of fibre in total. There are various foods one can then add to boost the fibre content further. I most often add the following:
1 tablespoon of chia seeds (5.4g fibre)
1 heaped tablespoon of ground flaxseeds (6.5g fibre)
1 tablespoon of hempseeds (1.4g fibre)
2 teaspoons of raw cacao (2.4g fibre)
As you can see those few additions bring the total amount of fibre in my breakfast bowl to close to 26g. Along with legumes or beans, nuts, wholegrains, and further fruit and vegetables during the day and you can see how easily one can achieve the recommended 45g or more.
Tips:
• Choose whole grain breads and pastas and brown rice over refined products
• Add beans or legumes into soups and stews instead of animal protein
• Swap juices for smoothies. The fibre lost through juicing will be blended into the smoothie.
• Include whole fruit and vegetables into every meal and snack
• Take time to read food labels and make the high fibre choice
I hope you will now be inspired to focus on fibre. Your friendly gut bacteria will thank you!
References:
- Burkitt DP. Eradicating sources or removing results. Postgrad Med J. 1983;59(690):232-235. doi:10.1136/pgmj.59.690.232
- Trowell HC, Burkitt DP. Diverticular disease in urban Kenyans. Br Med J. 1979;1(6180):1795. doi:10.1136/bmj.1.6180.1795-a
- Vipercore-13 (2014). Micronutrients & Dietary Fibre. [online] www.nrv.gov.au. Available at: https://www.nrv.gov.au/node/41.
- Greger, M. (2019). How not to diet : the groundbreaking science of healthy, permanent weight loss. New York: Flatiron Books.
- Daniel So, Kevin Whelan, Megan Rossi, Mark Morrison, Gerald Holtmann, Jaimon T Kelly, Erin R Shanahan, Heidi M Staudacher, Katrina L Campbell, Dietary fiber intervention on gut microbiota composition in healthy adults: a systematic review and meta-analysis, The American Journal of Clinical Nutrition, Volume 107, Issue 6, June 2018, Pages 965–983, https://doi.org/10.1093/ajcn/nqy041
- Mayo Clinic (2018). How much fiber is found in common foods? [online] Mayo Clinic. Available at: https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/in-depth/high-fiber-foods/art-20050948.