Does Oat Bran Contain Insoluble Fiber?

Whole grains are defined as containing all three original components of the grain: the germ, endosperm and bran of the grain kernel. Most of the fiber content is found in the outside bran layer. Oat bran is the outer layer of the oat kernel and it is high in soluble fiber, not insoluble fiber. Soluble fiber has many health benefits, including lowering your cholesterol. Since it is only one component of the grain, oat bran alone is not a whole grain.

Types of Fiber

Both soluble and insoluble fiber are important parts of your diet. Each day, women need around 25 g of fiber and men need as much as 38 g. Oat bran is high in soluble fiber, which dissolves in water and forms a gel-like substance that travels through your digestive tract. According to the American Heart Association, soluble fiber can help lower your blood cholesterol. In addition to oat bran, you can also get soluble fiber from beans, rice bran, peas and citrus fruits.

Insoluble fiber stays relatively intact in your gut and helps create fecal bulk. Since oat bran does not contain insoluble fiber, you will need to eat additional food sources to get all of your fiber. Wheat bran, carrots, cauliflower and apple skins are full of insoluble fiber. This fiber is not associated with low blood cholesterol, but it does keep your bowels functioning normally.

Additional Health Benefits

A study published by the "Journal of Nutrition" reports that consuming oat bran can decrease the cholesterol concentration in your blood. The study, conducted on rats, showed that oat bran can decrease your cholesterol by up to 1 percent. Both non-heated and baked forms of oat bran had similar effects on cholesterol. Baking oat bran may slightly change the chemical structure of the soluble fiber so that it acts like insoluble fiber by increasing fecal bulk. In addition to this, soluble fiber from oat bran can speed up absorption of essential vitamins and minerals.

Fiber Content

You can purchase oat bran in many forms such as hot cereal, cold cereal and baking mixes. A 1/3 cup serving of hot oat bran cereal provides 6 g of soluble fiber. Pancake mix enriched with oat bran has around 5 g of soluble fiber in 1/3 cup of batter. A 1 1/2 oz. oat bran muffin contains around 2 g.

Negative Effects

Consuming large amounts of fiber at one time can cause intestinal distress. According to the National Digestive Diseases Information Clearinghouse, soluble fiber from oat bran is completely broken down in the large intestine. This may cause you to experience gas and bloating. Consuming too much insoluble fiber at once can cause constipation or diarrhea. If you are increasing your fiber consumption, add a few grams each day as tolerated, to avoid adverse effects.