Dietary Fiber Vs. Soluble Fiber Vs. Insoluble Fiber

iComstock Images/Stockbyte/Getty Images

Fiber is an integral part of your diet, even though it is not a nutrient. Fiber is an indigestible substance, part of all plant-based foods, including fruits, vegetables, whole grains, legumes, nuts and seeds. Consuming a diet that includes plenty of whole plant-based foods enables you to fulfill your daily requirements of 38 g per day of fiber for men and 25 g per day for women. Consult your nutritionist if you have questions about fiber in your diet.

Dietary Fiber

Dietary fiber is the substance in plant-based foods that your stomach and intestinal enzymes do not digest. However; certain bacteria in your lower intestines may partly digest fiber. Plants vary in the types of fibers they contain, including pectin, lignin, cellulose, hemicellulose, gum and mucilage. In general, fiber falls into two categories, soluble fiber and insoluble fiber, each having certain biological roles that can benefit your health and treat diseases, disorders and medical conditions.

Soluble Fiber

Soluble fiber is indigestible substances in food that are soluble in water. These substances include pectin and gum found in fruits, vegetables, beans and whole grains, such as oats, particularly oat bran. Soluble fiber slows down the passage of food in the small intestines. Consuming foods high in soluble fiber may help you to reduce your blood cholesterol levels because the fiber reduces the amount of dietary cholesterol your body absorbs from food. Soluble fiber also slows down the absorption of sugar from foods into your blood, making it easier for you to control your blood sugar levels.

Insoluble Fiber

Insoluble fiber is substances in plant-based foods that are not soluble in water. These substances include lignin, cellulose and hemicellulose. Insoluble fibers increase the bulk of your stool and speed up the passage of waste through your digestive tract. Food sources of insoluble fiber include whole grains, such as wheat bran, beans and vegetables. Consuming foods with insoluble fibers helps you promote regular bowel movements and prevent constipation, hemorrhoids and diverticulosis.

Fiber From Whole Grains

Consuming a high fiber diet that includes whole grains may reduce your risk of death. Whole grains contain the entire seed kernel, including the bran, germ and endosperm, higher concentrations of nutrients and more fiber content. Research by scientists at the University of Minnesota School of Public Health in Minneapolis and published in the "Journal of the American College of Nutrition" in 2000 reports that older women who consume whole grains have a lower death rate from all causes than women who consume refined grains.