Iron bioavailability in green leafy vegetables cooked in different utensils

The effects of cooking utensils on the total and bioavailable iron contents of five green leafy vegetables, along with related promoters and inhibitors, were investigated. The cooked and fresh greens were analysed for moisture, total and bioavailable iron, ascorbic acid, dietary fibre, tannins, total oxalates and soluble oxalates by standard techniques. Moisture content of fresh greens ranged from 80–90%, total dietary fibre (5–11 g/100 g), oxalates (0.022–1.37 g/100 g) and tannin (41–166 mg/100 g). Cooking in different utensils had no effect on these parameters. Ascorbic acid content ranged from 8.7 to 88.3 mg/100 g in fresh greens and was reduced by 18–64% on cooking. The total and ionisable iron contents of greens ranged from 3 to 13 mg/100 g and 0.43 to 2.7 mg/100 g, respectively, and increased on cooking in iron utensil to 9.7 to 17.5 mg/100 g and 1.50 to 8.56 mg/100 g, respectively. The availability of iron, in relation to total iron, of greens cooked in iron utensils was either comparable or marginally higher than those cooked in other metallic utensils. Since the total iron content of greens cooked in iron utensils was high, the actual amount of available iron also increased. It can be concluded that cooking in iron utensils increases the total as well as the available iron content of greens.