Fiber, also known as roughage, is the indigestible part of plant foods that travels through our digestive system, absorbing water along the way and easing bowel movements.
Dietary fiber refers to nutrients in the diet that are not digested by gastrointestinal enzymes but still fulfil an important role.
Mostly found in vegetables, fruits, whole grains, and legumes, fiber has a host of health benefits, including reducing the risk of heart disease and diabetes.
In this article, we will look at the different types of fiber, why they are important, and what foods contain high levels of fiber.
Fast facts on fiber
Here are some key points about fiber. More detail and supporting information is in the main article.
Fiber is often split into two types: soluble and insoluble.
Dairy products and white bread have little to no fiber.
Cereal grains, seeds, vegetables, and fruits are good sources of fiber.
Fiber helps speed up the elimination of toxic waste through the colon.
Oat cereals, Brussels sprouts, oranges, flax seeds, and beans, such as kidney, black, and pinto, are all good sources of soluble fiber.
Fruits, vegetables, whole grains and legumes are all good sources of dietary fiber.
Eating fiber has many health benefits:
Protection against heart disease – according to the University of Maryland Medical Center, the consumption of soluble fiber has been shown to protect against heart disease by reducing cholesterol levels.
Gastrointestinal health – the consumption of fiber promotes regular bowel movements and prevents constipation. It may also reduce the risk of developing colitis and hemorrhoids. There is also mixed evidence that consuming fiber might help reduce the risk of colon cancer.
Diabetes – people with diabetes who consume a lot of fiber tend to need less insulin than those whose fiber intake is low. Fiber can help slow the absorption of sugar, helping to prevent spikes after meals.
Body weight – a high-fiber intake can significantly contribute toward body-weight control. Fiber produces a feeling of fullness without adding calories (fiber calories are not absorbed by the body) – this can help treat or prevent overweight/obesity.
Most foods that are high in fiber are also very healthy for other reasons. Take, for example, fruit, vegetables, and whole grains; they are high in fiber but also rich in vitamins and other essential nutrients. In other words, eating a high-fiber diet protects health through both the intake of fiber and other essential nutrients.
Fiber consists of non-starch polysaccharides, such as cellulose, dextrins, inulin, lignin, chitins, pectins, beta-glucans, waxes, and oligosaccharides.
There are two broad types of fiber: soluble and insoluble.
Soluble fiber dissolves in water. It changes as it goes through the digestive tract where it is fermented by bacteria. As it absorbs water, it becomes gelatinous.
Insoluble fiber does not dissolve in water. As it goes through the digestive tract, it does not change its form. It can also be fermented by bacteria in the colon.
Foods that contain dietary fiber are generally divided into predominantly soluble or insoluble; both types of fiber are present in all plant foods, but rarely in equal proportions.
Both forms of fiber have major health benefits.
Functions: Insoluble fiber
Insoluble fibers have many functions, including moving bulk through the digestive tract and controlling pH (acidity) levels in the intestines.
Benefits of insoluble fiber: