Foods High in Dietary Fibers

Dietary fiber is the indigestible part of plant-based food. Traditionally, scientists viewed fiber according to whether it was dissolvable in water (soluble) or not (insoluble). Today, dietary fiber is also evaluated according to how it changes in the body, such as whether it is fermented by bacteria in the digestive tract. Though pushing food through the body and easing defecation are most commonly associated with fiber, several other beneficial physiological effects have more recently been identified. For example, diets rich in fiber from whole grains, legumes, fruits and non-starchy vegetables are believed to reduce the risk of cardiovascular disease and Type 2 diabetes.

Legumes

Legumes are the most-fiber rich foods, with 15 to 19 g of fiber per one cup serving. In this category are lentils, most beans and peas. These all contain primarily soluble, viscous fiber that passes relatively slowly through the gut as a gel. This fiber reduces the absorption of cholesterol and moderates fluctuations in blood sugar by delaying the digestion of glucose. The fiber in legumes contributes to feelings of satiety, which can help control overeating.

Wheat Bran

The second highest source of fiber is wheat bran, with 17 g per cup. The fiber in wheat bran is primarily insoluble fiber. This means the fiber is not digested, and changes very little as it passes through the digestive tract. This sort of fiber helps maintain bowel regularity by increasing the bulk of feces. Because it also absorbs water, insoluble fiber softens stool, increasing transit time and easing passage.

Fruit

The next several high fiber foods are all fruits. Prunes, which contain 12 g per cup, Asian pears, which contain 10 g per cup, and raspberries, which contain 8 g per cup, are all excellent sources of dietary fiber. Like legumes, fruits are high in soluble fiber, but they also contain more insoluble fiber than legumes. The soluble fiber in fruit is fermentable. When bacteria in the gut act on it, the resulting short-chain fatty acids, including butyric, ethanoic (acetic), propionic, and valeric acids, are known to have beneficial health properties such as cancer prevention.

Quinoa

Quinoa is one of the least appreciated foods in the Western Hemisphere. Not only is it a rare vegetable source of a complete protein, it also contains 9 g of dietary fiber per cup. Quinoa is rich in lignans, a type of insoluble fiber associated with cardiovascular health and prevention of Type 2 diabetes. It is also an excellent source of manganese and magnesium.

Other Sources

Other foods high in dietary fibers include corn bran, nuts, seeds and root vegetables like potatoes and onions. Oat bran, rolled oats, whole oat flour, whole grain barley and dry milled barley are relatively few sources of beta-glucan dietary fiber. These foods are the only fiber sources for which the health claim of reducing heart disease has been approved by the FDA. Three grams or more per day are recommended for reduced risk of coronary heart disease.