Although your body absorbs very few nutrients from soluble fiber, this plant-based material provides essential health benefits. The soluble fiber in citrus fruits, apples and oats does not break down completely after you eat these foods. Instead, the fluids in your digestive tract turn this form of fiber into a jelly-like substance that slows your absorption of the nutrients in the foods you eat. Eating foods rich in soluble fiber may help regulate your bowel patterns, manage your blood sugar and reduce your cholesterol.
The word “soluble” refers to the way this form of fiber reacts when combined with water. Unlike insoluble fiber, or roughage, which does not dissolve in water, soluble fiber dissolves partially into a viscous mass, the Harvard School of Public Health, or HSPH, notes. Whole-wheat breads and cereals, celery, carrots, tomatoes, brown rice and seeds contain insoluble fiber -- rough or stringy plant matter that adds bulk to digestive wastes and help them pass more easily through your system. Oatmeal, avocados, nuts, dried beans and peas, lentils, apples, pears and berries are high in soluble fiber. Many grains, vegetables, fruits and legumes contain both soluble and insoluble fiber, but the proportions of each type of fiber in each food varies.
Although soluble fiber isn’t as bulky as insoluble fiber, soluble fiber can regulate bowel function by increasing the weight of stools and stimulating muscle activity in your colon. If your digestive system can’t tolerate large amounts of roughage, soluble fiber may be a more gentle alternative for correcting constipation. Dietary supplements such as psyllium husk use the laxative effects of soluble fiber to promote regular bowel movements. Paradoxically, bananas, oats and other foods that are rich in soluble fiber may also help relieve diarrhea by creating formed, solid stools.
When you eat foods that are rich in soluble fiber, the gelatinous material that forms during digestion slows the absorption of nutrients from these foods. Foods that are high in both soluble fiber and carbohydrates, such as apples, prunes, beans or oatmeal, break down more slowly as a result of their fiber content, which prolongs the conversion of carbohydrates into glucose, a crucial source of energy for your brain and muscles. A slower release of glucose results in a sustained release of energy and a less significant increase in your blood sugar. Eating foods that contain soluble fiber helps you keep your blood sugar stable, which may reduce your risk of type 2 diabetes, according to the HSPH.
Foods that are high in soluble fiber, especially oats, dried peas, beans and lentils, may help reduce the amount of low-density lipoprotein, or “bad” cholesterol, in your bloodstream, according to the Linus Pauling Institute. By reducing serum cholesterol, soluble fiber prevents the accumulation of fatty plaques on arterial walls and lowers your risk of coronary heart disease. To benefit from the preventive properties of fiber, the Institute of Medicine recommends that women ages 19 to 50 eat at least 25 g of fiber each day, and men in this age group eat at least 38 g of fiber each day. Eating a wide variety of high-fiber foods in combination with a diet low in cholesterol and saturated fat may improve your cardiovascular health.
- Mayo Clinic Health Letter: Vitamin F: Is Fiber a Vitamin?
- Harvard School of Public Health: Fiber: Start Roughing It – What Should You Eat? – The Nutrition Source
- Linus Pauling Institute at Oregon State University: Micronutrient Information Center: Fiber
- University of Maryland Medical Center: Psyllium