Dietary Fiber means “Nutrients in the diet that is not digested by gastrointestinal enzymes.” It is the indigestible part of plant foods that pushes through our digestive system, absorbing water along the way and easing bowel movements. Fiber is made up of non-starch polysaccharides, such as cellulose, dextrins, inulin, lignin, chitins, pectins, beta-glucans, waxes and oligosaccharides. The word Fiber is misleading, because many types of dietary fibers are not Fibers at all.
Types of Fiber
There are two broad types of fiber,
- Soluble Fibers. Soluble dissolves in water, Soluble Fiber changes as it goes through the digestive tract, where it is fermented by bacteria. Soluble Fiber absorbs water, as it does so becomes gelatinous.
- Insoluble Fibers. Insoluble does not dissolves in water. Insoluble Fiber goes through the digestive tract without changing its forms.
No fiber can be digested; both types of fiber are present in all plant foods, but rarely in equal proportions.
Benefits of Insoluble Fiber
Insoluble Fibers have many functions, including moving bulk through the digestive tract, and controlling pH (acidity) levelsin the intestines.
- Promotes regular bowel movements and prevents constipation
- Speeds up the elimination of toxic waste through the Colon
- By keeping an optimal pH in the intestines, Insoluble Fiber helps prevent microbes from producing substances which can lead to Colorectal Cancer
Sources of Insoluble Fiber
- Vegetables – especially dark green leafy ones
- Root vegetable skins
- Fruit skins
- Whole wheat products, wheat bran
- Corn bran
- Nuts and seeds
Benefits of Soluble Fiber
Soluble Fiber binds with fatty acids, slows down the time it takes to empty the stomach, and slows down the rate of sugar absorption by the body.
- It reduces Cholesterol, especially levels of LDL (Bad Cholesterol)
- It regulates sugar intake, this is especially useful for people with Diabetes and Metabolic Syndrome
Sources of Soluble Fiber
- Kidney beans
- Pinto beans
- Brussels sprouts
- Fruits (raw)
- Grains Oatmeal
- Whole-wheat bread
Insoluble vs. Soluble Fiber should be 75% to 25%, or 3 parts insoluble to every 1 part soluble. As most High-Fiber Containing Foods usually have both types, it should not be necessary to be too careful about dividing them up. Oat, oat brans, psyllium husk and flax seed are rich in both types of Fibers. In other words, your focus should be on Fiber intake in general, rather than what Type Of Fiber.
Excess of Fiber
Switch from a Low Fiber Diet to a High Fiber Diet can create some abdominal pain and increased flatulence. Also, Very High Fiber Diets (more than 40g daily) are linked with decreased absorption of some important minerals, such as iron, zinc and calcium. This occurs when fiber binds these minerals and forms insoluble salts, which are then excreted. This could increase the risk of developing deficiencies of these minerals in susceptible individuals. Adults should aim for a diet that contains 25-30g of fiber per day and should introduce fiber into the diet gradually to avoid any negative outcomes.
Dietary Fiber and Weight Loss/ Weight Control
Dietary Fiber slows down the rate of sugar absorption, thereby help to lose weight. Moreover, Insoluble Dietary fiber reduces the urge for more food thus reducing the total high calorie food intake.