inositol, any of several stereoisomeric alcohols similar in molecular structure to the simple carbohydrates. The best known of the inositols is myoinositol, named for its presence in muscle tissue, from which it was first obtained in 1850. Myoinositol is essential for the growth of yeasts and other fungi; it is widely distributed in plants and animals, and large amounts of it are present in the human body, principally as a constituent of a phospholipid that is abundant in the brain. Myoinositol is commonly obtained from grains, in which it is present as the hexaphosphate, phytic acid.