"Grains require careful preparation because they contain a number of antinutrients that can cause serious health problems. Phytic acid, for example, is an organic acid in which phosphorus is bound. It is mostly found in the bran or outer hull of seeds. Untreated phytic acid can combine with calcium, magnesium, copper, iron and especially zinc in the intestinal tract and block their absorption. This is why a diet high in improperly prepared whole grains may lead to serious mineral deficiencies and bone loss. The modern misguided practice of consuming large amounts of unprocessed bran often improves colon transit time at first but may lead to irritable bowel syndrome and, in the long term, many other adverse effects."