Soluble fiber absorbs liquid, forming a gel, which can help resolve diarrhea by removing excess fluid from the bowel. It can help lower blood cholesterol and glucose levels, too. Soluble fiber-rich foods include strawberries, blueberries, apples, avocado, dried figs and prunes, oranges, and mangos; veggies such as asparagus, edamame, broccoli, green beans and peas, carrots, plus legumes, oats, barley, psyllium, and peanuts, which contain the highest soluble fiber per serving of all nuts. Almonds, Brazil nuts, sesame and sunflower seeds are good sources, as well. Insoluble fiber passes through the intestines largely intact. It increases stool bulk, which can help resolve constipation. Ancient whole grains top the list of insoluble fiber-rich foods, along with air-popped popcorn, zucchini, broccoli, cabbage, leafy greens, and root vegetables. It is also contained in legumes, most beans, raspberries, unpeeled apples and grapes, walnuts, almonds, and sunflower seeds. Some foods give you a two-for-one, because they contain both types of fiber. For example, oats, legumes, mangoes, almonds, avocados, cucumber, celery, and carrots. Generally, you need to eat some of each type of fiber.