8 Fibre
Complex carbohydrates often contain indigestible fibre. There are two types of fibre; insoluble and soluble. Insoluble fibre does not dissolve in water and promotes efficient intestinal functioning by improving the elimination process. Cellulose, lignin, and hemicellulose are the main fibres in this category.
The second type is soluble fibre, which does dissolve in water. Like insoluble fibre, this fibre is not digested; however, soluble fibre acts as sponge, slowing the digestion of food in the stomach and intestines and absorbing fats and other chemicals. Some research suggests that soluble fibre absorbs cholesterol and will lower blood cholesterol levels. The main soluble fibres are pectin and gums.
Water must be present for either fibre to perform any useful function in the human body. Without water, both types of fibre are simply dry irritants that cannot be passed from the body.
The types of fibres and their sources are shown in Table 4.
| Fibre | Type | Sources |
| Cellulose | Insoluble | Wheat flour, beans, cabbage family, apples, root vegetables (including beets, carrots, potatoes, turnips, and yams) |
| Hemicellulose | Insoluble | Whole grains, cereals, bran |
| Lignin | Insoluble | Cereals, mature vegetables, eggplant, green beans |
| Pectin | Soluble | Apples, grapes, squash, citrus fruits, strawberries |
| Gums | Soluble | Oat bran, lentils, dried beans, legumes |
Table 4: Types of dietary fibre
Health Canada recommends that Canadian women need 25 g of dietary fibre daily and men need 38 g daily. Health Canada also states that men are only getting half of the suggested amount (Health Canada, Do Canadian Adults Meet Their Nutrient Requirements Through Food Intake Alone?, 2012). Such information provides opportunities for the food industry to offer products that contain dietary fibre. Some suggested ingredients for increasing fibre are fruit and vegetables, whole grain flour, nuts, and seeds.
