No matter what your perception of fiber is, believe me when I say that it is far more than just something you need to eat to keep “regular.” Actually, fiber is a collective term for the indigestible polysaccharides in our diets, both the natural ones in foods and others that come from “functional” sources extracted or isolated from foods or manufactured synthetically (such as Metamucil).
As for its solubility in water, fiber is either soluble or insoluble. Soluble fiber, found in oatmeal, legumes, seeds, fruits (apples, bananas, citrus fruits), and vegetables, dissolves in water and is partially metabolized in the large intestine by “friendly” bacteria that normally reside there. This type of fiber may play a large role in removing cholesterol from the body. The insoluble form is found in vegetables (carrots, celery, and the skins of corn kernels), parts of fruit (apple peels, core, and seeds), brown rice, and whole grains (such as the outer membranes of wheat kernels).This fiber, acting as roughage, passes through your digestive system without being fully digested, primarily serving to increase fecal bulk and ensure regular elimination of bodily waste products. Since both kinds of fiber pull some water out of your body, it is best to add an extra glass or two of water to go along with consumption of more fiber.
Despite the well-known fact that a high-fiber diet may help reduce your chances of developing heart disease, diabetes, obesity, strokes, colorectal and other types of cancer, diverticulosis, and hemorrhoids, most Americans still don’t eat enough fiber. If you are at high risk of developing type 2 diabetes, a diet high in fiber can enhance your insulin sensitivity and help lower your risk. A portion-controlled, low-GI diet containing Mexican-style foods (pinto beans, whole-meal wheat bread, and low-GI fruits) can also improve glucose levels in obese people with type 2 diabetes due to its low GI value and high fiber content.
Fiber is also helpful because it generally slows down the rate at which food empties from your stomach, thus limiting rapid BG peaks. It also increases satiety, meaning that you feel full longer, which may help prevent excessive eating and weight gain. Foods that are higher in fiber are also, on the whole, lower in added sugars, fat, and calories. As discussed, the best strategy to control your diabetes is not to eliminate carbohydrates per se, but rather to eat higher-fiber carbohydrates–which means most of the foods with a lower GI value and lower GL. If you eat a low-fiber food like a candy bar, you will likely still feel hungry afterward despite an excessive intake of calories, and your BG will go up too much. If, on the other hand, you eat a high-fiber apple along with a small handful of nuts or a chunk of low-fat cheese, it will take you longer to eat, and in the end you will feel more satisfied despite having eaten fewer calories.
Next week, I’ll talk more about how much fiber you really need to eat.