Fibers and dietary fibers

Fiber is the indigestible part of plant foods that pushes through our digestive system, absorbing water along the way and facilitating bowel movements.

The word fiber (North American) can also be spelled fibre (Brittish). It comes from the Latin word fibra, meaning fiber, thread, string, filament, entrails. Dietary fiber refers to nutrients in the diet that are not digested by gastrointestinal enzymes.

Basically, the term fiber refers to carbohydrates that cannot be digested. Fiber is present in all plants that are eaten for food, including fruits, vegetables, grains, and legumes. The consumption of foods high in fiber have been found to reduce appetite. However, not all fibers are the same, and there are a number of ways to categorize it. One is by its source or origin. For example, fiber from grains is referred to as cereal fiber. Another way of categorizing fiber is by how easily it dissolves in water. Soluble fiber partially dissolves in water. Insoluble fiber does not dissolve in water. These differences are important when it comes to the fibers effect to prevent or diminish the risk of certain diseases:

Soluble fibers

  • Soluble fiber dissolves in water. It changes as it goes through digestive tract, where it is fermented by bacteria. As it absorbs water, it becomes gelatinous which is an important property for the health benefits.
  • Soluble fiber binds with fatty acids, slows down the time it takes to empty the stomach and the rate of sugar absorption by the body.

The benefits are:

  • It reduces cholesterol, especially levels of LDL (bad cholesterol).
  • It regulates sugar intake, this is especially useful for people with diabetes and metabolic syndrome.

Insoluble fibers

  • Insoluble fiber does not dissolve in water. As it goes through the digestive tract, it does not change its form. Actually, the bulking fibers absorb water as they move through the body, preventing constipation.
  • Insoluble fibers have many functions, including moving bulk through the digestive tract, and controlling pH (acidity) levels in the intestines.

The benefits are:

  • Promotes regular bowel movements and prevents constipation.
  • Speeds up then 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.
  • Works as a prebiotica


In oats, like in flakes or wholemeal oat flour, you will normally find approx. 4% soluble fibers (beta glucans) and 6% insoluble fibers. Usually, on the food packages, only the total fiber content is declared, in this case being 10% dietary fibers.

Fiber is an important part of a healthy diet – at least 20 grams a day and more is better. The best sources are whole grain foods, actually wheat and oat bran seems to be more effective than similar amounts of fiber from fruits and vegetables. As fiber intake is increased, the intake of beverages should also be increased, as fiber absorbs water.

A high fiber intake can also significantly contribute towards body weight control. Fibers fills up adding negligible amount of calories and can help treat or prevent overweight and obesity.