What You Need to Know About Fibre

A lot of people are concerned with the amount of protein they consume daily, but did you know that most Canadians only get half of the amount of fibre they need everyday?

What is fibre?

Dietary fibre is non-digestible plant carbohydrates. Non-digestible means that the plant carbohydrates are not digested or absorbed in the small intestine. Usually these non-digestible carbohydrates make up part of plant cell walls. Because of this, fibre is only naturally found in plant foods.

Last week we talked about prebiotics and probiotics- probiotics can feed off of non-digestible fibre, making it wonderful for our gut health. To read more about prebiotics and probiotics, see the article here.

Different types of fibre

Typically, fibre has been categorized as soluble or insoluble. All fibre-rich foods contain both soluble and insoluble fibres, however, some foods are higher in one or the other. For example, many fruits and vegetables tend to be higher in insoluble fibres, whereas oats, beans, peas and lentils tend to be higher in soluble fibre.

Past studies have shown that soluble fibre is traditionally good for forming “gels” in our digestive system, is fermentable, decreases blood glucose and blood cholesterol. Insoluble fibre helps to promote regularity and a healthy digestive system, keeping stool moving through our digestive system.

However, recent studies have shown that soluble and insoluble fibre are not always consistent in their roles. For example, some soluble fibres don’t seem to lower blood cholesterol or blood glucose, but instead help to improve gut health and regularity. Some insoluble fibre doesn’t contribute to stool bulk.

Studies that previously classified fibre as soluble or insoluble were typically using fibre that was isolated from plant foods, whereas more recent studies use the whole plant food. Therefore, the terms “soluble” and “insoluble” to describe fibre will likely be phased out, and instead the terms “viscous” or “fermentable” will be used instead.

Benefits of fibre

The viscosity of fibre is thought to be responsible for its incredible health benefits (davis & melina, 2014). Viscous fibre helps to slow down stomach emptying, keeping us feeling full for longer, and makes us feel more full after eating. Viscous fibre can stabilize blood glucose levels, making it an important part of the glycemic index, and reduce blood cholesterol.

Fermentability of fibre also has huge health benefits. As discussed in this post, bacteria in our large intestines feed on fibre and ferment it, creating short chain fatty acids. These fatty acids are used by the body for energy. Eating a fibre rich diet helps to keep these gut bacteria healthy.

Fibre impact on health

GI Health

Fibre helps to prevent constipation and damage to the digestive system  (diverticulutis and hemorrhoids). It may also protect against colorectal cancer, inflammatory bowel disease and gallstones. Non-viscous (traditionally insoluble) fibre is the most useful in this regard.

Heart Disease

Studies show that increased fibre intake decreases total cholesterol levels and LDL cholesterol. A pooled analysis of studies showed that each additional 10 grams of fibre added to the diet was associated with a 14% decrease in risk of coronary events and a 27 percent decrease in risk of coronary death.

Diabetes

Studies have shown that increasing the amount of fibre in the carbohydrate-rich foods that we eat, while maintaining the same amount of carbohydrates eaten, may help reduce the risk of developing type 2 diabetes by stabilizing our blood glucose (essentially eating a lower glycemic index diet). Fibre slows down the absorption of fat and carbohydrates from the small intestine, which decreases insulin levels and blood glucose.

Weight

Eating nuts and other high fibre food have been associated with lower body weight over time. This is likely due to them being less energy dense, allowing us to fill our stomachs with a larger volume while eating a lower amount of calories. Foods high in fibre also keep us feeling fuller for longer. I strongly believe that eating a whole foods, plant-based, high fibre diet is one of the healthiest and and most maintainable ways to lose weight without feeling hungry.

How much fibre do we need?

It is suggested that men consume 38 grams of fibre per day and women consume 25 grams per day. However, 32-45 grams per day may be more ideal to have optimal digestion. However, the typical Western diets currently get about half of this recommendation. For a more comprehensive look of how much fibre we should be eating, see this chart.

Fibre rich foods

Fibre is found in abundance in vegetables, fruit, whole grains, beans, peas, lentils, nuts and seeds.

Soluble fibre sources:  apples, oranges, carrots, okra, eggplant, oats, barley, psyllium, beans, peas and lentils.

Insoluble fibre sources: some vegetables and fruit, whole grains, brown rice and wheat bran.

Ways to increase fibre intake

Grains: look for whole wheat, with 2-4g of fibre per serving. Try to stick to brown rice, whole wheat bread, flour, and pasta, and grains like quinoa and buckwheat. I

If you’re just transitioning to whole wheat pasta or brown rice instead of white, try cooking half whole wheat/brown and half white to get used to the flavour. Overtime, you might come to prefer the whole wheat/brown rice.

Vegetables and Fruit: Incorporate whole fruits, vegetables, and smoothies into your diet rather than juices. Juices (even fresh pressed ones) take away the fibre from the fruit and vegetables, meaning they won’t keep you full as long and may spike blood sugar.

When possible, keep the skins on potatoes, carrots, apples, cucumber and other fruits and vegetables to get the most fibre. Make sure to wash these fruits and vegetables well when keeping the skin on.

Read this blog post for more tips on how to incorporate more fruits and vegetables into your diet.

Legumes: Try adding beans and lentils to meals such as soups, stews, salads, and stir fries. Add a spread of hummus to your usual sandwich, or add lentils to a pasta sauce.

Nuts and Seeds: Add flaxseed or chai seeds to your usual smoothie or oatmeal (and reap the added benefit of omega-3s!). Have a small handful of nuts as a snack, or spread nut butter on your favourite fruit.

The key to increasing your fibre intake without bloating or gas is to do so slowly. For a few days, try switching to whole grain breads, or increasing your fruits and vegetables by a serving or two. After a few days, try incorporating a few more servings of high fibre foods like beans and legumes, best done by increasing by 1/4 cup every few days. At first, you might experience more bloating and gas. This is only temporary, and your body will adjust. Be sure to drink enough fluid (about 1/2 of your body weight in ounces) and incorporate regular physical activity in your day.

Sources 

Wong JM, Comelli EM, Kendall CW, Sievenpiper JL, Noronha JC, Jenkins DJ. Dietary Fiber, Soluble and Insoluble, Carbohydrates, Fructose, and Lipids. InThe Microbiota in Gastrointestinal Pathophysiology 2017 (pp. 187-200).

Schulze MB, Liu S, Rimm EB, Manson JE, Willett WC, Hu FB. Glycemic index, glycemic load, and dietary fiber intake and incidence of type 2 diabetes in younger and middle-aged women. The American journal of clinical nutrition. 2004 Aug 1;80(2):348-56.

Hartley L, May MD, Loveman E, Colquitt JL, Rees K. Dietary fibre for the primary prevention of cardiovascular disease. Cochrane Database Syst. Rev. 2015.

den Besten G, van Eunen K, Groen AK, Venema K, Reijngoud DJ, Bakker BM. The role of short-chain fatty acids in the interplay between diet, gut microbiota, and host energy metabolism. Journal of lipid research. 2013 Sep 1;54(9):2325-40.

Hodge AM, English DR, O’Dea K, Giles GG. Glycemic index and dietary fiber and the risk of type 2 diabetes. Diabetes care. 2004 Nov 1;27(11):2701-6.

Gray, J.: Dietary Fibre. Definition, analysis, physiology and health. In ILSI Europe Concise Monograph Series (pp.35), 2006. Brussels: ILSI Europe.

Gibson GR. Fibre and effects on probiotics (the prebiotic concept). Clinical Nutrition Supplements. 2004 Jan 1;1(2):25-31.

Unlock Food. Getting more fibre. 2017. Retrieved from http://www.unlockfood.ca/en/Articles/Fibre/Getting-More-Fibre.aspx?aliaspath=%2fen%2fArticles%2fFibre%2fGetting-more-fibre

Gray J. Dietary fibre: definition, analysis, physiology & health. ILSI Europe; 2006.

FNB (Food and Nutrition Board). Dietary Reference Intakes: Proposed Definition of Dietary Fiber.

Mozaffarian D, Hao T, Rimm EB, Willett WC, Hu FB. Changes in diet and lifestyle and long-term weight gain in women and men. New England Journal of Medicine. 2011 Jun 23;364(25):2392-404.

Anderson JW, Baird P, Davis RH, Ferreri S, Knudtson M, Koraym A, Waters V, Williams CL. Health benefits of dietary fiber. Nutrition reviews. 2009 Apr 1;67(4):188-205.

Streppel MT, Arends LR, van’t Veer P, Grobbee DE, Geleijnse JM. Dietary fiber and blood pressure: a meta-analysis of randomized placebo-controlled trials. Archives of internal medicine. 2005 Jan 24;165(2):150-6.

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