ZINC BIOAVAILABILITY AND TEA CONSUMPTION - STUDIES IN HEALTHY HUMANS CONSUMING SELF-SELECTED AND LABORATORY-CONTROLLED DIETS

One self-selected study (study A) and one laboratory-controlled study (study B) were conducted to investigate the effect of tea consumption on zinc bioavailability in healthy humans. The 14-day study A consiste d of two 7-day experimental periods, while the 28-day study B consiste d of two 14-day experimental periods. In study A eight subjects and in study B ten subjects were participated. Subjects of study A consumed self-selected diets and kept a record of foods eaten. In study B, subj ects ate a constant and weighted laboratory controlled diet. In both s tudies, subjects consumed 8 g of instant tea during tea supplementatio n periods. Complete urine and fecal collections were made by subjects of both studies. Zinc contents of urine, fecal and food samples were d etermined by using Atomic Absorption Spectrophotometer. Mean zinc inta kes of humans consuming self-selected diets were below the RDA. Mean u rinary zinc excretion, fecal zinc excretion and zinc balance were unaf fected by the tea consumption. Negative zinc balances in study A and p ositive zinc balances in study B were observed in both tea and no tea dietary treatments. Tea consumption showed a small but not statistical ly significant adverse affect on zinc bioavailability in humans.