Antioxidants from green tea or rosemary extract may affect the absorption of dietary iron, a recent study suggests.
Scientists in the Human Nutrition department at The Royal Veterinary and Agricultural University sought to determine the effect of phenolic-rich extracts obtained from green tea or rosemary on nonheme-iron absorption.
Young women aged 19-39 consumed test meals on 4 separate occasions. The meals were identical except for the absence (meal A) or presence (meal B) of a phenolic-rich extract from green tea (study 1; n = 10) or rosemary (study 2; n = 14). The extracts (0.1 mmol) were added to the meat component of the test meals. The meals were extrinsically labelled with either 55Fe or 59Fe and were consumed on 4 consecutive days in the order ABBAor BAAB. Iron absorption was determined by measuring whole-body retention of 59Fe and the ratio of 55Fe to 59Fe activity in blood samples.
The presence of the phenolic-rich extracts resulted in decreased nonheme-iron absorption. Mean (±SD) iron absorption decreased from 12.1 ±4.5% to 8.9 ± 5.2% (P < 0.01) in the presence of green tea extract and from 7.5 ± 4.0% to 6.4 ± 4.7% (P < 0.05) in the presence of rosemary extract.
From their results the researchers concluded that phenolic-rich extracts used as antioxidants in foods reduce the utilisation of dietary iron.
Authors of the study:Samir Samman, Brittmarie Sandström, Maja Bjørndal Toft, Klaus Bukhave, Mikael Jensen,Sven S Sørensen and Marianne Hansen