Fibre Research

Many people think of dietary fibre as a single, simple food component but fibre is a complex and varied macronutrient. In fact, it has been suggested that measuring the total fibre content of a food is about as useful as measuring the total vitamin content of a food. Dietary fibre can be defined as: "the plant polysaccharides and lignin, which are resistant to hydrolysis by the digestive enzymes of man". Note that the term polysaccharides is plural, indicating that many different sugar polymers make up dietary fibre. The aforementioned definition refers to the biochemical nature of fibre but not to its action in the digestive tract. Many studies have shown that fibre can have a profound effect on digestive events in the small intestine, even though it is not digested in the small intestine but rather fermented in the large intestine. This effect arises because of the chemical nature and physical attributes of dietary fibre. It is complicated by the complex and varied chemical structure of fibre itself. In addition to the fact that fibre is composed of many different chemical forms, one must also be aware that fibre composition differs depending on the source.

This fascinating mix of polymers and lignin forms the basis for the lab's current research interests. At present the effect(s) of fibre in the digestive tract are being studied with particular emphasis on the potential interaction between dietary fibre and other foods. To study this interaction, the effects of fibre on the digestion of other dietary components such as carbohydrates, fats and minerals are examined. This research is multifaceted. For example, one may wish to know how fibre affects the hydrolysis and absorption of starch and other carbohydrate polymers in the small intestine. In addition to addressing these questions, the interaction of minerals with dietary fibre and fibre-associated components is also being investigated to ensure that higher fibre diets will not impact mineral status. Other projects include a study of the interaction between fibre, fermentation and the bioavailability of folate to ensure folate adequacy in the diet. All these projects will have ramifications for Canadians. Numerous health effects have been attributed to dietary fibre and many individuals have sought to improve their health by increasing their fibre intake.

The research contributes to many areas of the Food Program including setting policy and standards for defining dietary fibre and regulating the addition of fibre to foods as well as determining the safety and physiological effects of food processing or changes in food composition on food digestibility. These activities are important to Health Canada to ensure the safety and health promoting effects of fibre to the benefit of all Canadians.