Dietary fibre is the portion of plant-derived food that cannot be completely broken down by human digestive enzymes. Dietary fibres are diverse in chemical composition and can be grouped generally by their solubility, viscosity, and fermentability, which affect how fibres are processed in the body. Furthermore, fibre and fibre supplements can be categorized as soluble or insoluble. Many people are unfamiliar with what soluble and insoluble fibres really are, and the benefits they have for our health.
Understanding The Different Kinds of Fibre
Soluble Fibre
Soluble fibre attracts water, dissolves in water and turns into a gel-like substance. The major benefit of soluble fibre is that it slows digestion, thus stabilizing blood sugar by delaying the absorption of glucose. Thus, soluble fibre plays a role in the prevention of diabetes, as well as obesity. By slowing digestion, not only do soluble fibres increase the uptake of minerals and nutrients during digestion, but they also promote satiety and help prevent overeating. Psyllium, apples, beans, dried apricots, and oat bran are all excellent sources of soluble fibre.
Insoluble Fibre
Insoluble fibre does not dissolve in water. It acts to increase stool volume, otherwise known as a bulking agent. Insoluble fibre helps to maintain regularity by increasing transit time, promoting regularity and healthy bowel contractions. Some examples of insoluble fibre include wheat, corn, rice, vegetables and beans. Insoluble fibre may help to prevent and treat haemorrhoids, varicose veins, and constipation. These fibres also help to promote the removal of toxins through the bowel, before they are given a chance to be reabsorbed into the bloodstream, wreaking havoc on the body. It is this action that gives it such an important role in the prevention of colon cancer, among many other inflammatory diseases.
Fermentable Fibre
Recently there has been some dispute about the relevance of dividing fibre into soluble and insoluble categories. As an alternative, fibre can be divided into ‘viscous’ and ‘fermentable’. Soluble fibres that are high in inulin or fructo-oligosaccharides are said to be fermentable. Friendly bacteria in the large intestine ferment these fibres. These fibres can also be called probiotics. They help to stimulate the selective growth of "good" intestinal bacteria (mainly the lactobacillus and bifidobacterium species), at the expense of "bad" bacteria. Bacteria like e-coli and clostridium species are also normal and necessary as parts of healthy gut flora, but if overgrown or unopposed, are more likely to cause infection. Another advantage of fermentable bacteria is a fatty acid called butyric acid, produced through the fermentation process and the primary fuel of the large intestine. Other short-chained fatty acids produced by the fermentation process are thought to be responsible for some of the cholesterol-lowering properties of fibre. Leeks, onion, garlic, asparagus, Jerusalem artichoke and chicory root are all high in inulin.
Viscous Fibre
Also primarily associated with soluble fibre, viscous fibres are the cholesterol-lowering specialists. These fibres are complex with bile acids, which are made by the liver from cholesterol and are necessary for the proper digestion of fats. After complexing with bile acids, these compounds are removed from circulation and in turn lower cholesterol levels.
Categories of Dietary Fibre
- Cellulose - found in bran, legumes, peas, root vegetables, cabbage family, outer covering of seeds, and apples
- Hemicellulose - found in bran and whole grains. Regulates the water content of the stool. It is used as a treatment for weight loss, constipation, detoxification and the prevention of colon cancer.
- Polyfructoses (Inulin and Oligofructans)
- Galactooligosaccharides
- Gums - found in oatmeal, barley, and legumes.
- Mucilages
- Pectins - found in apples, strawberries, and citrus fruits. Pectin slows the absorption of food after meals thereby decreasing the rate at which blood sugar enters the body. Apple pectin binds to fats and bile acids. Thus it is used to prevent gallstones and lower cholesterol. Citrus pectin has been studied for its ability to remove toxins from the body and reduce side effects from radiation therapy.
- Lignin - found in root vegetables, wheat, and fruits with edible seeds (such as strawberries). A fibre that has an affinity for fats and bile acids. It binds to these substances in the intestines and prevents their absorption or desorption into the body. Lignin is used to lower cholesterol, prevent gallstones and treat diabetes and colon cancer.
- Resistant Starches - found in ripe bananas, potatoes
How To Add Fibre Supplements To Your Daily Routine
Fibre can be added to your diet by increasing your intake of whole grains, fresh fruit and vegetables (with skin) and beans/lentils. If it is still needed, many fibre supplements are available, each with a unique mix of fibres in tablets, capsules or powder form, are available.
Potential Cautions & Considerations
Read fibre supplements carefully because some may contain laxatives, making those preparations unsuitable for long-term use.
The recommended intake of fibre is anywhere from 25-40 g/day, a goal that can be achieved quite easily if you know how to make the most of your diet. 2 pieces of whole-wheat toast or 3/4 cups of cooked oats have about 6 g of dietary fibre. A cup of spinach has 7 g, while 1/2 of cooked black beans have just fewer than 10 g of fibre.
