Fiber, both types, part of healthy diet

DEAR DOCTOR K: Can you explain the difference between soluble and insoluble fiber? Are both good for your health?

DEAR READER: Dietary fiber consists of the indigestible parts of plant foods. As you note, there are two kinds. Soluble fiber dissolves in water; insoluble does not. Both are important for healthy digestion, and both can help prevent heart disease, obesity, diabetes, diverticulitis (an intestinal malady) and constipation.

Soluble fiber absorbs water in the stomach and intestine. It forms a gel that slows digestion. This causes you to feel full and may help with weight loss. Soluble fiber also slows the digestion and absorption of glucose, which is important for controlling diabetes. Finally, it decreases LDL (bad) cholesterol in the blood, which helps lower the risk of heart disease.

Good sources of soluble fiber include nuts, seeds, legumes (lentils, beans and peas), oat cereals, fruit pectin (found in citrus fruits, apples, pears, apricots and peaches), and some vegetables, such as carrots.

Insoluble fiber passes through the small intestine without breaking down. It’s important for intestinal health because it adds bulk and draws water to the stool. This aids its passage through the large intestine.

Good sources of insoluble fiber include whole grains, wheat and corn bran, popcorn, seeds, nuts, broccoli, cabbage, root vegetables, onions, green leafy vegetables, and fruit and vegetable skins.There are other health benefits from diets that are high in the fiber-rich foods mentioned above. Those foods contain antioxidants, “good fats” and “good carbs,” as well as fiber, and provide a healthy source of protein.

So I strongly recommend using foods rather than supplement powders that you can get over-the-counter at drugstores as the primary source of fiber. The supplement powders seem to help many patients with their constipation when added to fiber-rich diets, but I never recommend just the supplements alone.