Ascorbic acid and mineral availability in two Nigerian plant foods.

This paper reports the effect of various concentrations of ascorbic acid on the availability of Fe, Zn, Ca and Mg in two popular plant foods--cowpea and amaranthus vegetable--in Nigeria. Ascorbic acid enhancement of iron availability was over 300 % and zinc by 200 % from 0-100 mg concentration. Availability of iron was further increased by 200 mg ascorbic acid in amaranthus but showed a 50 % decrease in the legume. Availability of zinc was decreased by 200 mg ascorbic acid but to different levels in both plant foods. In the legume, maximum enhancement of Ca and Mg availability was exhibited at 100 mg ascorbic acid level but suppressed at higher concentrations. In amaranthus, maximum Ca enhancement was exerted by 200 mg ascorbic acid and 50 mg for Mg. Enhancement of Cu in the legume was marginally affected by ascorbic acid concentrations while inhibition of Cu was observed in amaranthus between 50-300 mg ascorbic acid concentrations. The effect of ascorbic acid on the availability of minerals seems to be concentration dependent and varies with theplant food.