Bioavailability of iron and zinc as affected by phytic acid content in rice grain

Abstract

Phytic acid (PA) is considered as an anti-nutritional factor (ANF) present in cereals and legumes and bind to cationic minerals including iron (Fe) and zinc (Zn), thus reducing their bioavailability in both ruminants and nonruminants. The present study was aimed at finding the impact of PA on bioavailability of Fe and Zn. Six rice cultivars with contrasting PA were evaluated for total phosphorus (P), PA, Fe, and Zn in brown and processed rice. A significant correlation of PA of brown rice with PA of milled rice (r = .69) was observed. PA and Zn content were negatively correlated (r = −.55) in brown rice while no significant correlation was found between PA and Zn in milled rice. The rice cultivar Bindli, with lowest PA (0.82 g/100 g) was found to exhibit high Zn bioavailability, while PB267, with highest PA (2.62 g/100 g) showed low Zn and Fe bioavailability. Practical applications Rice is staple food for millions of people, especially the Asians. Fe and Zn are essential micronutrients required for human growth and development, but the rice grain is deficient in Fe and has only moderate amounts of Zn. The bioavailability of these minerals are impaired by PA which chelates and bind cationic minerals in both ruminants and nonruminants. Screening of rice genotypes with low PA and high minerals bioavailability may be suitable for people suffering from micronutrient malnutrition.