Prebiotics vs Dietary Fibre

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If you’re up-to-date, you will know we just laid out the differences between probiotics vs prebiotics. By getting enough prebiotics in our diet, we can improve the number and variety of good bacteria in our gut, supporting better overall gut health.  Aside from the importance of prebiotics, you’ve probably heard how important it is to get fibre in your diet. Fibre and prebiotics are both key dietary components to promote health. Understanding their differences is important so you can make informed decisions about your digestive health. Let’s jump into it!

First, let’s review what dietary fibre is.  

Fibre describes plant material that your body cannot digest or absorb. Unlike fats, proteins or carbohydrates which your body breaks down and absorbs, fibres pass through and remain relatively intact through your stomach, small intestine and colon on its way out of your body. In other words, fibre binds with your body’s waste products, helping it move through the proper channels!  

It’s extremely important to make sure you get enough fibre in your diet. The best way to incorporate fibre into your diet is to make sure you’re consuming a high volume of plant-based foods, like fruits, veggies and whole grains. There are two types of fibre, soluble and insoluble, and both have different benefits for gut health. Insoluble fibre helps keep bowel movements regular. Soluble fibre dissolves in water to form a gel and helps to either bulk up loose stools, or soften firm stools. Soluble fibre can also help to lower blood cholesterol and control blood sugars.  

Below is a quick chart to show you some foods that contain both soluble and insoluble fibres: 

Soluble Fibre
e.g. Pectin, beta-glucan  
Insoluble Fibre 
e.g. Cellulose 
Legumes e.g. beans, lentils 
Oats 
Barley 
Apples 
Citrus fruits 
Avocado 
Chia seeds 
Wholegrain foods 
Wheat bran 
Corn and corn bran 
Nuts  
Vegetables e.g. cauliflower, broccoli, green beans, spinach, kale 
Fruits, especially fruit skins 

What are prebiotics?  

Prebiotics are defined as “a substrate that is selectively utilized by host microorganisms conferring a health benefit.”1 In other words, they are food for our gut microbiota. Prebiotics are indigestible parts of food that ferment in the gut and feed the good bacteria. The good bacteria then produce ‘short chain fatty acids.’ Short chain fatty chain acids play an important role in nourishing the cells of our gut barrier, contributing to a functioning immune system, and so much more.  

By getting enough prebiotics in our diet, we can improve the number and variety of bacteria in our gut, supporting better overall gut health.  

CDHF’s gut health expert and registered dietitian Andrea Hardy “when we don’t fuel our gut bacteria with enough prebiotics, bacteria have to find fuel from other sources. It has been shown in animal models that bacteria will eat the all-important mucous layer in your gut – which is your first line of defence against invasion of potentially harmful compounds”.2 

Prebiotics can be naturally found in many foods like legumes, fruits, certain nuts, seeds and grains. There are quite a few products on the market to which manufacturers have added prebiotics (for example: cereals, protein supplements, energy bars, and “healthier” cookies, to name a few).  

While most prebiotics are a type of fibre, not all fibres are prebiotics! To be classified as a prebiotic, the fibre must pass through the GI tract undigested and stimulate the growth and/or activity of certain good bacteria in the large intestines.3 Prebiotic fibres in our diets include inulin, fructans and galacto-oligosacharides (GOS). Some foods that are naturally high in prebiotics are:  

Vegetables Jerusalem artichokes, garlic, onion, asparagus cabbage, snow peas, green peas, leeks, shallots 
Fruit Apples, grapefruit, pomegranate, nectarines 
Whole Grains Oats, wheat, barley, rye crackers 
Nuts and Seeds Pistachio nuts, cashews  
Legumes Red kidney beans, soybeans, chickpeas, lentils 

How much should you be getting?  

While there isn’t a recommended daily amount of prebiotics to consume, Health Canada recommends 25 grams of fibre per day for women and 38 grams of fibre per day for men.4   

According to Bélanger et al.5 the actual intakes of dietary fibre for Canadian men is 19.1 grams per day and for women is 15.6 grams per day. So most Canadians are only getting about half of the recommended fibre intake. 

We know it can be tough. Next time you are at the grocery store, spend time exploring the produce section, it’s the largest section in the store. Fill your cart with lots of colourful fruits, vegetables and try to buy in season. That way you can reach your daily dose of 25 to 38 grams, without even having to think about it! 

More of a Visual Learner? Download our Infographic

dietary fibre vs prebiotics

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References: 

  1. Gibson, G.R., Hutkins, R. Sanders, M.E., Prescott, S.L., Reimer, R.A., Salminen, S.J., Scott, K., Stanton, C., Swanson, K.S., Cani, P.D., Verbeke, K., & Reid. G. (2017). Expert consensus document: The International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on the definition and scope of prebiotics. Nature Reviews Gastroenterology & Hepatology, 14(8), 491-502. https://doi.org/10.1038/nrgastro.2017.75.  
  1. Hardy, A. (2020). How prebiotics help gut health. Retrieved February 22, 2021, from https://ignitenutrition.ca/blog/how-prebiotics-help-gut-health.   
  1. Holscher, H.D. (2017). Dietary fiber and prebiotics and the gastrointestinal microbiota. Gut Microbes, 8(2),172-184. https://dx.doi.org/10.1080%2F19490976.2017.1290756.  
  1. Health Canada. (2019). Fibre. Retrieved March 6, 2021 from https://www.canada.ca/en/health-canada/services/nutrients/fibre.html.  
  1. Bélanger, M., Poirier, M., Jbilou, J., & Scarborough, P. (2014). Modelling the impact of compliance with dietary recommendations on cancer and cardiovascular disease mortality in Canada. Public Health, 128(3), 222-230. https://doi.org/10.1016/j.puhe.2013.11.003.