A Dietitian's Guide to Fibre Supplements

Most Canadians are not getting enough fibre in their diets. If you are looking to improve your fibre intake and support your health, you may be wondering if a fibre supplement is right for you. In today's blog we'll explore the most common fibre supplements on the market and what the science says about the various options.

Before we dive into the supplements, let’s do a quick recap on fibre in general. We can categorize fibre into two main categories: soluble and insoluble. Many high fibre foods contain both types of fibres.

Insoluble fibre helps with bulking of our stool and speeds up the movement of waste through our digestive track. Insoluble fibre is commonly found in foods like fruits and vegetables, bran, whole grains and nuts/seeds. Increasing this type of fibre can be one tool to help with the management of constipation.

Another category of fibre is soluble fibre. It can be found in foods like whole grains, some fruits and vegetables, legumes and nuts/seeds. It dissolves in water and some types of soluble fibre can help with bulking the stool. It can be used to help manage both constipation and diarrhea. Soluble fibre can be further categorized as viscous (typically gel-forming) and non-viscous. The viscous gel-forming kind has been shown to lower cholesterol and improve blood sugar. Soluble fibre also has some really unique benefits for health, because of its positive impact on the gut microbiome. This type of fibre feeds our good gut bacteria, through the process of fermentation, which helps create short chain fatty acids (SCFA). These compounds help strengthen our gut lining, reduce inflammation and can help reduce our risk of chronic diseases like diabetes and heart disease. Fibre does more than just help you poop!

Now that we've reviewed the types and functions of fibres found in food, let's look at the supplements commonly found on the market in Canada.

Psyllium husk in a bowl with a spoon

Psyllium: The Classic Bulk-Forming Fibre Supplement

Psyllium is one of the most widely studied fibre supplements and readily available in stores in both husk form and powder/supplement form. It is also added to some cereal products.

• How it works: Psyllium is a viscous soluble fibre so it absorbs water and forms a thick gel. This helps soften and bulk stool, making it easier to pass.

• Research highlights: Studies show that psyllium can be effective in lowering LDL (bad) cholesterol and can help lower blood sugar after eating, when taken with meals. It also can help reduce constipation or diarrhea in those with IBS.

• Considerations: Psyllium must be taken with plenty of water to avoid choking or blockages. Some people may experience bloating or gas. It also doesn't dissolve clear so this may not be everyone's cup of tea (or cup of fibre, ha!). Available in pill form too but you need to take several pills to get the same dose as the powder.

• Tips: You can mix the powder into oatmeal, sprinkle on yogurt or make a jam/jelly with fruit.

  
  

Psyllium is a good choice if you want a fibre supplement that supports both digestion and heart health.

Beta Glucan: Fibre Supplement from Oats and Barley

Beta-glucan is a soluble fibre found mainly in oats and barley. It has gained attention for its heart health benefits.

• How it works: Like psyllium, beta-glucan forms a viscous gel in the gut, which slows digestion and binds cholesterol.

• Research highlights: This fibre is naturally found in oats are barley and has been shown to be effective for reducing LDL cholesterol and blood sugar (when taken with a meal). May improve digestive symptoms but more research is needed.

• Note: This fibre supplement is not the same molecular structure of the yeast/mushroom derived beta-glucan supplement that has been claimed to improve immune function (these claims have also not yet been supported by good quality human research).

• Considerations: Similar considerations to psyllium - make sure to drink enough water. It does not dissolve clear and it does gel.

  
  

If your goal is to improve cholesterol and support heart health, beta-glucan is an effective option with strong scientific backing. You can also get it from whole foods like oats and barley - so consider including those in your diet!

Wheat Dextrin: A Versatile and Tasteless Fibre

Wheat dextrin is a soluble fibre derived from wheat starch. It is often used in powdered fibre supplements and drinks.

• How it works: It dissolves easily in water and is tasteless, without thickening much, making it a convenient option for adding fibre to beverages or foods.

• Research highlights: Research on this fibre is more limited and while it is sometimes used to help with regularity, it has not been specifically studied for IBS.

• Other uses: Commonly used in clinical settings (as it won't clog a feeding tube).

• Considerations: May worsen GI symptoms in some individuals.

  
  

Wheat dextrin is a good choice if you want a neutral-tasting fibre supplement that mixes easily and supports gut health. The scientific evidence for its use is not as strong as other options.

Partially Hydrolyzed Guar Gum (PHGG): Gentle and Prebiotic

PHGG is a water-soluble fibre made by breaking down guar gum, a natural thickener from guar beans.

• How it works: PHGG is fermented by gut bacteria, producing short-chain fatty acids that nourish the colon and reduce inflammation.

• Research highlights: Clinical trials show PHGG improves stool consistency (reducing diarrhea and constipation) and improves bloating. It acts as a prebiotic fibre by feeding the beneficial gut microbes. It is well tolerated and a good option for those looking for a fibre supplement to help with their IBS symptoms.

• Considerations: PHGG is low in viscosity, so it does not thicken liquids much and is easy to consume. Start with a smaller dose and gradually increase over a few days/weeks to let your gut adjust. It can take a few weeks to see positive effects.

  
  

PHGG is ideal if you want a gentle fibre that supports digestion and acts as a prebiotic to feed your gut microbiome.

Inulin: A Natural Prebiotic Fibre

Inulin is a type of soluble fibre found in plants like chicory root, onions and garlic. It is also often added to food products (fibre gummies, fibre cereals or granola bars). It is classified as a fructan.

• How it works: Inulin is a non-viscous soluble fibre that resists digestion in the small intestine and ferments in the colon, feeding beneficial gut bacteria.

• Research highlights: Current research indicates prebiotic properties and inulin may. help increase certain types of beneficial gut bacteria, including Bifidobacteria. While some studies indicate other possible benefits, more research is needed.

• Considerations: Inulin can cause gas and bloating, especially in those with IBS. Not recommended as a supplement for those with sensitivity to fructans.

  
  

Inulin may have benefits for gut health but it may not the best fibre supplement if you have IBS.

Mason jars filled with high fibre foods including quinoa, vegetables and chickpeas

The Bottom Line

While supplements can be helpful in some situations, they do not replace the benefits of whole foods. Foods rich in fibre like vegetables, fruits, whole grains, legumes, nuts/seeds, also contain many beneficial compounds that have additional health benefits (vitamins, minerals, antioxidants and more!) that we don’t get from a fibre supplement. Food is always best, but as we have discussed today, there can be a role for supplements in certain situations.

If you are looking to add a fibre supplement to your routine, consider choosing one based on the benefit you are looking for and indication of the supplement.

With any fibre supplement, it is important to start slow (consider even half the starting dose listed on the package) and gradually increase over a couple weeks. Make sure you increase fluid when increasing your fibre. Also - be patient, results likely won’t show up overnight.

Also, if you are dealing with constipation and your bowel is full of stool, adding more fibre may not help and may make your symptoms worse (until things are cleared out). It’s always best to talk with your doctor, pharmacist or dietitian before starting a new supplement. You may need other management options prior to adding fibre to your diet. Managing digestive symptoms like constipation or IBS often needs a multi-layered and individualized approach - what works for one person may not work for another!

Digestive symptoms can be stressful and hard to navigate. Working with a Registered Dietitian experienced in digestive health can help you cut through the confusion, find the right approach for your body, and come up with a plan that eases your symptoms so you can start enjoying food again and feeling your best.

If you are located in Alberta and looking for a digestive health dietitian, I would love to help - feel free to reach out or book a free discovery call!

Anna Maria

References:

1. Yasukawa Z, Inoue R, Ozeki M, et al. Effect of repeated consumption of partially hydrolyzed guar gum on fecal characteristics and gut microbiota: a randomized, double-blind, placebo-controlled, and parallel-group clinical trial. Nutrients. 2019.

2. Niv E, Halak A, Tiommny E, et al. Randomized clinical study: partially hydrolyzed guar gum (PHGG) versus placebo in the treatment of patients with irritable bowel syndrome. Nutrition & Metabolism. 2016.

3. White N. A guide to recommending fiber supplements for self-care. American Journal of Lifestyle Medicine. 2020.

4. Lambeau KV, McRorie JW. Fiber supplements and clinically proven health benefits: how to recognize and recommend an effective fiber therapy. Journal of the American Association of Nurse Practitioners. 2017.

5. Monash University FODMAP Diet. Fibre supplements & IBS. monashfodmap.com/blog/fibre-supplements-ibs

6. Monash University FODMAP Diet. Research update: dietary fibre in the era of microbiome science. monashfodmap.com/blog/research-update-dietary-fibre-era-microbiome-science

7. Deehan EC, Duar RM, Armet AM, Perez-Muñoz ME, Jin M, Walter J. The prebiotic potential of inulin-type fructans: a systematic review. Advances in Nutrition. 2022.