A single serving of white flour is generally considered to be 1 cup, which is approximately equal to two slices of bread. This single serving contains 455 calories, 1.2 grams of fat and 3.4 grams of dietary fiber.
White flour is refined to remove the germ and bran. Most refined flour is also enriched with certain nutrients that have been lost during preparation, specifically iron, B vitamins and calcium. A typical serving of white flour provides 32 percent of the recommended daily allowance of iron and 2 percent of the recommended daily allowance of calcium. Nutritionally, the biggest difference between enriched white flour and whole wheat flour is in the fiber content. On average, whole wheat flour contains five times the dietary fiber found in white flour. Dietary fiber is associated with a lower risk of coronary disease, type 2 diabetes and certain gastrointestinal cancers.