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Eur J Nutr. 2007 Dec;46(8):453-9. Epub 2007 Dec 1.

Both aluminum and polyphenols in green tea decoction (Camellia sinensis) affect iron status and hematological parameters in rats.

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Unité de Recherche sur les Composés Antioxydants, Stress Oxydant, Eléments Traces et Maladies Métaboliques, Ecole Supérieure des Sciences et Techniques de la Santé de Tunis, BP 176, Bab-Souika, 1006 Tunis, Tunisia.



Green tea leaves naturally contain high levels of polyphenols and aluminum (Al). Polyphenols in green tea decoction are considered to be one of the major factors responsible of low iron status. However, the effects of Al from green tea decoction on iron status and hematological parameters remained unclear.


The objective was to investigate the Al absorption from green tea decoction and studied its influence on iron status and hematological parameters in rats.


During the experiment period, rats were given the experimental diet + a simple dose of Al sulfate with or without graded doses of green tea decoction (25, 50 and 100 g/l). The Al absorption was evaluated in the serum; however, iron status was evaluated by the iron concentration in the liver, kidney, spleen and femur. In addition, the hemoglobin and hematocrit were evaluated.


Our results showed that the serum Al significantly increased between 61.5 and 342%, as tea doses-dependant. The Al sulfate significantly decreased the reserve of iron in all studied organs between 21.7 and 17% (P < 0.05). In groups receiving green tea decoction alone or Al + graded doses of tea, the reserve of iron significantly decreased in all studied organs between 59.4 and 18.5% (P < 0.01). Al alone or associated with drinking doses of tea significantly decreased hemoglobin concentration between 23.6 and 9% (P < 0.05) and hematocrit between 12.7 and 7% (P < 0.01).


Our data showed that Al from green tea decoction was more absorbed in the serum than Al sulfate. Al absorption was associated with low iron status and reduction of hemoglobin and hematocrit. Considering that Al competes with iron in different stage of erythropoiesis including transferrin binding, so we could assume that the negative effect of tea on iron status arises not only from polyphenols iron complexes but also from Al released in tea decoction.

[Indexed for MEDLINE]

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