Comparative evaluation of green and black tea consumption on the iron status of omnivorous and vegetarian people
The effect of tea polyphenols on the bioavailability of iron and the iron status of man is controversially discussed. Especially women prior to menopause are a vulnerable group regarding their iron status, with a vegetarian diet increasing this risk. This study aimed to determine several iron status parameters for men and women consuming a mixed diet or being vegetarians and drinking tea. In a cross-over study, the effect of tea consumption on the iron status of healthy male and female omnivorous compared to vegetarian volunteers was tested. All volunteers consumed either green tea or black tea (each 1. L/d) for four weeks together with meals or avoided tea for four weeks (cross-over design). Blood samples were withdrawn prior to the one week depletion period, at the start of the intervention phase and thereafter weekly during intervention. The iron status parameters hemoglobin, hematocrit, transferrin, total iron and iron binding capacity were not affected by the consumption of tea. In contrast, plasma ferritin values were significantly reduced after tea consumption, especially in those women with basal ferritin values lower than 25++g/L, already after two weeks of intervention with tea (1. L/d). -® 2011 Elsevier Ltd
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