Fibre has been linked with reducing the risk of heart disease, diabetes, obesity and certain types of cancer. Although the term “fibre” has been used widely by medical and nutrition experts, what does it really mean when you are told to “increase your fibre intake?” Is simply eating more fibre enough to maximize the health benefits?
A New Perspective
With new research we learn more about the different types of fibre. New terms are being suggested for the different types of fibre which may help shape future nutrition guidelines. The Standing Committee on the Scientific Evaluation of Dietary Reference Intakes has proposed the following definitions for fibre:
Dietary Fibre consists of naturally occurring plant materials that your body cannot digest. Examples include fibre naturally found in whole grain breads and cereals, beans, lentils, fruits and vegetables.
Functional Fibre consists of manufactured or synthetic plant and animal materials that your body cannot digest. These fibres have health benefits, such as bowel regularity, and control of blood cholesterol and blood sugar levels. These fibres can be found on their own or added to foods. Examples include oat B-glucan, psyllium and inulin.
Total Fibre is the sum of dietary fibre and functional fibre.
Dietary vs. Functional Fibre, What’s the Difference?
Most of us are familiar with the term dietary fibre. This is the fibre we eat that occurs naturally in foods. However, you may be wondering why we need a definition for functional fibre. Due to the advances in food processing and technology, we now have the ability to design, isolate and concentrate different fibres and fibre-like substances that do not meet the traditional definition of fibre. More importantly, these substances may also have specific health benefits. So don’t be surprised if you see recommendations for specific functional fibres in the future.
Soluble vs. Insoluble fibre? Viscous vs. Fermentable? I think I need a dictionary.
Both dietary and functional fibre can be further divided into those that are soluble and those that are insoluble. However, experts continue to debate over the use of these terms because they may not be the best way to describe the different types of fibre and their health benefits. Experts are now proposing that these terms be replaced with “viscosity” and “fermentality”.
Soluble fibres are found in foods such as oat bran, psyllium, legumes, vegetables (e.g. okra and eggplant), barley and certain types of fruits. These fibres are known to reduce blood cholesterol levels and control blood sugar levels. Do you notice how oats and barley form a “sticky and gummy” texture when they are cooked? This “stickiness” is referred to as viscosity and experts believe this is what gives these fibres a “two thumbs up”! Fermentability refers to the digestion of soluble fibre by “friendly” bacteria in our intestines which is also important for promoting health. However, not all soluble fibres are viscous and fermentable, so buyer beware!
Insoluble fibres, such as those found in wheat bran, corn bran, flax seeds, and some vegetables and fruit (especially the skins), passes through your digestive system largely unchanged. This is what is often referred to as roughage and bulk. These fibres are generally not viscous or fermentable, but they serve an important role in promoting bowel regularity. Just make sure you drink enough water with this fibre so that it will work well!