Very few studies have addressed the question of adverse effects of consuming high quantities of spice extracts or polyphenolic antioxidants. Since one of the postulated mechanisms of antioxidant action is chelation of pro-oxidant metals such as iron, a recent human study examined the effect of polypheno-lic-rich green tea and rosemary extracts on the absorption of nonheme iron (71). It was found that green tea and rosemary extracts added to foods decreased absorption of nonheme iron by around 20%, indicating that indeed iron was chelated by the extracts. Therefore, caution is required in dealing with iron-deficient populations.
A study was carried out investigating the embryotoxic effects of rosemary extract in pregnant rats (72). Twenty-six milligrams of a 30% (w/ v) R. officinalis aqueous extract was administered by gavage during two different periods of Wistar rat pregnancy. No effects of rosemary extract were observed on postimplantation loss or fetus anomalies but a slight, though not significant, increase in preimplantation loss was observed. The authors conclude that this finding might explain the use of the plant aqueous extract as an abortive in Brazilian folk medicine, but further studies using higher doses would be required to demonstrate a significant effect.
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