Phytic acid is found in the grains and seeds of many plants. Its presence in the diet may restrict the absorption of many major and trace elements from the digestive tract. The interactions of this compound with intestinal digesta compounds can reduce protein and starch digestibility. This leads to reduced nitrogen retention and causes a milder rise in glycemia during absorptive phase. Phytic acid also has antineoplastic properties, can prevent renal stone formation and some heart diseases. This compound is synthesized in mammalian tissues and its ability to bind specifically with some cellular proteins has been demonstrated. In this paper an outline of the most important metabolic effects of phytic acid is presented. It is also attempted to explain some of the mechanisms of its action based on data from the literature.