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Effects of green and black tea on iron uptake, storage, and availability for free radical reactions.

Authors
Harris-G; Leonard-S; Baer-D
Source
FASEB J 2006 Mar; 20(4):A623
NIOSHTIC No.
20030103
Abstract
The interaction of iron with tea is important to health not only because tea polyphenols bind iron, but also because polyphenols may release iron from ferritin storage, resulting in free radical formation. In this study, we tested the effects of green and black teas on iron uptake and ferritin storage in Caco-2 cells, and on iron availability for free radical reactions in a cell-free system. Green and black teas (3 types each) were brewed at 1g/100ml for 5 minutes and tested for total phenol content. The two green and black teas most similar in total phenol content were used for subsequent experiments. Caco-2 cells were grown to confluence over 21 days and subsequently treated for 24 hours with 1, 2, or 4% green or black teas in the presence or absence of 100uM ferrous sulfate and ImM vitamin C. Green tea (at 2 and 4%) and black tea (at 4% only) reduced soluble intracellular iron content, apical iron content (at all levels except 1 % green), as well as intracellular ferritin (green at 2 and 4%, black at 4%) in Caco-2 cells (P < 0.05). Both black and green teas, at 15% strength, released iron from ferritin storage and induced significant (p < 0,0001) increases in hydroxyl radical formation in the presence of 110mg/ml ferritin. These data indicate that green and black teas reduce soluble intracellular and apical iron levels, and that they also reduce intracellular ferritin levels. Green tea was most effective at reducing intracellular iron levels. In addition, both teas are capable of releasing iron from ferritin storage and inducing free radical formation in the presence of ferritin.
Keywords
Iron-compounds; Free-radicals; Phenols
CODEN
FAJOEC
CAS No.
7439-89-6
Publication Date
20060301
Document Type
Abstract
Fiscal Year
2006
NTIS Accession No.
NTIS Price
Issue of Publication
4
ISSN
0892-6638
NIOSH Division
HELD
Priority Area
Research Tools and Approaches: Cancer Research Methods
Source Name
The FASEB Journal
State
WV
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