Types of Fiber

Soluble Fiber and Insoluble Fiber

Both soluble and insoluble fiber are undigested. They are therefore not absorbed into the bloodstream. Instead of being used for energy, fiber is excreted from our bodies. Soluble fiber forms a gel when mixed with liquid, while insoluble fiber does not. Insoluble fiber passes through our intestines largely intact.

Soluble fiber has no calories because it fully passes through the body. Soluble fiber is not found in foods like bran and raw leafy green vegetables. Foods appearing fiberous need not be high in fiber like lettuce. The whole grains, cereal foods, fruits, vegetables and nuts, in general, are good sources of soluble fibers.

Not All Fibers are alike. They can be divided into two categories: insoluble fiber and soluble fiber. Both are important for health. Foods contain different amount and type of fiber. Some foods are better sources of one type than the other. For example, oat bran contains about 50% soluble fiber of the total, but wheat bran contains only 20% soluble fiber of the total fiber. Both types of fibers are important for good health. Health experts recommend 20 to 30 grams of fiber each day.

Insoluble Fiber

Insoluble fiber is a coarse material that does not dissolve in water. It is a roughage. Insoluble fiber should be taken with enough water. It swells and softens the stool and stimulates the intestinal muscles to relieve constipation. Insoluble fiber reduces pressure in the intestine by increasing the movement of food through the intestine.

Increasing the bulk and speed of food moving through the intestinal tract reduces time for harmful substances to build in intestine. This may help prevent cancer of the colon. 

Soluble Fiber

Soluble fiber is made up of sticky substances like gums and gels and dissolves in water. Studies have shown that foods high in soluble fiber can lower the blood cholesterol of people who are on a low-fat, low cholesterol diet. Soluble fiber probably increase the passage of bile acids through the digestive tract and cholesterol is taken out of the blood.

Scientific studies have shown that oat bran, oatmeal and beans significantly reduce blood cholesterol. Corn bran, carrots and apples can also reduce cholesterol. Increased soluble fiber with complex carbohydrates in meals can make the hormone insulin work better resulting in slowing down the release of food into the intestine and keeps the blood sugar from rising rapidly. 

High Fiber Foods: Brans- wheat bran, oat bran, corn bran, rice bran. 

Moderate Fiber: Whole Grains- Whole wheat flour, whole wheat pasta, oatmeal- rolled oats, steel cut oats, whole-oat flour, cornmeal, brown rice.

Low Fiber Foods: Refined Items- White flour (bleached/unbleached), pasta, cream of wheat, oat flour, cornstarch, white rice.

Below is a list of foods with their total fiber content, soluble fiber content and insoluble fiber content.