phytic acid

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A compound, C₆H₁₈O₂₄P₆, found abundantly in seeds and the bran of grain, that is the principal storage form of phosphorus in plants. Phytic acid is a strong chelator of calcium, zinc, and other minerals essential for animal metabolism, and diets based on foods high in phytic acid, such as unrefined flour, can cause mineral deficiencies unless it is broken down by the sprouting of the seeds or the fermentation of the foods by acid-producing bacteria such as those found in sourdough leaven.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun organic chemistry The compound inositol hexaphosphoric acid' present in cereals etc as alkali and alkaline earth salts; it is a source of phosphorus for ruminants but is indigestible for carnivores