Phytic acid and phosphorus in crop seeds and fruits: a global estimate

A very important mineral storage compound in seeds is phytate, a mixed cation salt of phytic acid (myo-inositol hexakis phosphoric acid). This compound is important for several reasons: (1) It is vital for seed/grain development and successful seedling growth. (2) It is often considered to be an antinutritional substance in human diets, but it may have a positive nutritional role as an anti-oxidant and an anti-cancer agent. (3) It represents a very significant amount of phosphorus being extracted from soils and subsequently removed with the crop. (4) It plays a role in eutrophication of waterways. A key part of this review is an estimate of the annual tonnage of phosphorus and phytic acid sequestered in up to 4.1 billion metric tonnes of crop seeds and fruits globally each year. We estimate that nearly 35 million metric tonnes of phytic acid, containing 9.9 million metric tonnes of P, is combined with about 12.5 and 3.9 million metric tonnes of K and Mg respectively, to form each year over 51 million metric tonnes of phytate. The amount of P in this phytate is equal to nearly 65% of the elemental P sold world wide for use in mineral fertilizers. Dry cereal grains account for 69% of the total crop seed/fruit production but account for 77% of the total phytic acid stored each year. Low phytate mutants, that are now available for some key staple food crops such as maize and barley, offer potential benefits in such areas as the sustainability of lands used to grow crops, the mineral nutrition of humans and animals, and reduction in pollution of waterways.