In vitro bioavailability of iron from spinach (Spinacea oleracea) cultivated in soil fortified with graded levels of iron and zinc.

A pot-culture experiment was conducted to assess the bioavailability of iron from spinach cultivated in soil fortified with graded levels of iron and zinc (FeSO4 x 7H2(0) and ZnSO4 x 7H2(0), respectively). Applications of varying levels of iron to soil increased the total iron and phosphorus contents and decreased the zinc content (P < 0.05). The effect of applying varying levels of zinc was the opposite of on the minerals in spinach. The ascorbic acid content was remarkably reduced with varying levels of iron and zinc. Higher levels of zinc and lower levels of iron in the soil increased the bioavailability of iron from spinach (P < 0.05). In conclusion, the interactions of 15 ppm zinc with 30 ppm iron significantly enhanced the bioavailability of iron, total iron and zinc contents.