Bioavailability of Zinc in Bread Wheat Grown in the Calcareous Soils of the Kurdistan Region of IRAQ

A survey of wheat grain from 120 fields in Sulaimanyah province, Kurdistan region, Iraq was undertaken in 2017. We evaluated the concentrations of phosphorus (P), Zn and phytic acid (PA) and the estimated Zn bioavailability in wheat grain grown in the calcareous soils of the region. Concentrations of P in wheat grain were higher than the recommended value of 3570 mg kg− 1; PA was within the range of other countries but Zn concentration in 88% of wheat grain samples fell below the value recommended for human nutrition of 41.6 mg kg− 1. Bioavailable Zn intake (mg d− 1) was estimated assuming bread consumption of 300 g day− 1 in the region. Considering PA and Zn intake suggested only 21.5 ± 2.9% of whole grain flour Zn was bioavailable. Thus the effective Zn intakes from whole wheat was only 1.25–2.05 mg d− 1 for the local population. Typical dietary Zn was below recommended levels (11 mg d− 1), due to low soil Zn uptake by wheat and the large concentrations of PA in wheat grains, probably from over-use of phosphate fertilizer.