Anti-nutrient Composition and Bioavailability Prediction as Exemplified by Calcium, Iron and Zinc in Melocia corchorifolia Leaves

Abstract

Plants are the major sources of microelements to populace of the developing world. However, presence of antinutritional factors limit their optimal utilization. In this paper, antinutritional content and their effect on bioavailability of Ca, Fe and Zn in Melocia corchorifolia leaves was investigated. The result indicated that the plant leaves had high level of tannin (4,689.06±2.60 mg/100 g dry weight, DW). The concentration of other antinutritional factors per/100 g DW is as follows: phytate (88.57 mg), total oxalate (585.00 mg), soluble oxalate (217.50 mg), cyanide (16.02 mg) and nitrate (74.41 mg). The predicted Ca, Fe and Zn bioavailability showed that [Oxalate]/[Ca] and [Oxalate]/[(Ca + Mg)] are below the critical level of 2.5 known to impair calcium bioavailability. Furthermore, [Phytate]/[Ca], [Phytate]/[Fe] and [Phytate]/[Zn] are below the critical level of 0.5, 0.4 and 1.5 respectively. However, [Ca][Phytate]/[Zn], 16.72, is above the critical level of 0.5, which indicates significant effect of phytate on Zn bioavailability. From the results it can be concluded that M. corchorifolia leaves could be an important bioresource for Ca and Fe but not for Zn considering the predicted bioavailability.