A Global Estimate of Phytic Acid and Phosphorus in Crop Grains, Seeds, and Fruits

Abstract

THIS chapter considers phytate more from the perspective of what plants deposit into the crop seeds/grains/fruits that we use than from the human and animal nutrition perspective. We provide a synopsis of the results of a global survey by Lott et al. [1] of the phosphorus (P) and phytic acid (PA) deposited each year in the world’s major seed/grain/fruit crops, correct an error in those data, and extend the data to give information nutritional scientists can access more easily. It is important to point out that the beneficial and problematic aspects of phytic acid extend beyond animal nutrition aspects. Phytates, which are consumed in food by humans, swine, poultry, and other monogastric animals, often end up contributing to the eutrophication of our lakes and rivers through deposition of P-containing waste products [2]. The manure disposal problems associated with intensive animal farming operations are now widely recognized [3]. When animals are fed on grains/seeds, most of the total P consumed is PA-P, and thus, a large amount of the P in manure must be from phytate phosphorus that was not absorbed by the farm animals [4,5]. Phytate occurs in protein bodies and often, but not always, assembles into small, dense spheres called globoids [6–8]. Phytate concentration may vary in different tissues of a seed/grain/fruit [9,10]. Phytate is used by all seeds/grains/fruits as a mineral nutrient store for the growing seedlings. Generally, phytate accounts for one to several percent of the dry weight of grains and other dry seeds [1,11]. It provides substantial myo-inositol, P, K, and Mg to the growing seedling, and perhaps Ca, Fe, Zn, and Mn [11–15]. The synthesis and roles of phytate in plants have been reviewed by Greenwood [16], Lasztity and