Beans offer more fiber than most plant foods, plus they're loaded with healthy plant protein. 1  1 cup of canned minestrone soup = about 5 grams fiber. 2  1/2 cup vegetarian or fat-free refried beans, used to make microwave nachos = about 6 grams. 3  1/4 cup kidney beans, added to a green salad = 3 grams fiber.