STUDIES ON THE BIOAVAILABILITY OF ZINC IN HUMANS .9. INTERACTION OF BEEF-ZINC WITH IRON, CALCIUM AND LACTOSE

Three series of zinc absorption experiments using the plasma zinc appearance approach were conducted in healthy volunteers following ingestion of 400 g of cooked beef containing 16 mg of zinc. In the first study, Fe/Zn ratios of 1:1 and 4:1 - but not 7:1 - constituted from 16, 64 and 112 mg of ferrous iron from ferrous sulfate, accompanied by ascorbic acid, produced a significant reduction in the post-beef zinc response. In the second study, 240 ml of cow's milk, both with intact lactose and with 90% of the carbohydrate hydrolyzed to glucose and galactose, produced a 63% and 96% reduction respectively in plasma zinc uptake from the standard beef dose. There was no differencial effect of lactose. In the final study, 300 mg of calcium alone, or with 64 mg of ferrous iron, produced a significant reduction in plasma zinc appearance. No deinhibition of the effect of the 4:1 Fe/Zn ratio by the competing calcium was observed.