Research suggests thatblack teaandgreen tea, both high incaffeine, may interfere with the absorption.
Herbal teas, which have no caffeine, may have little to no effect.
While it may seem to assume that caffeine is the culprit, that’s actually not the case.
Verywell / Anastasia Tretiak
This includesheme ironfound in animal products such as meat and fish andnon-heme ironderived from plant sources, including nuts.
The high consumption ofblack teaalso appears to have the same effect.
In both instances, the culprit impeding iron absorption istannin.
Tannins are potent polyphenol compounds that give tea, coffee, and red wine their dry and puckery taste.
With respect to green tea, the evidence is split as to whether it can affect iron absorption.
Does Caffeine Affect Iron Absorption?
Caffeine does not affect iron absorption.
While the inhibition of hepcidin may not improve iron absorption, it in no way interferes with absorption either.
What About Herbal Tea?
Black, white, and green tea all come from the leaves of theCamellia sinensisplant.
The leaves and buds ofC.
sinesis area rich source of tannin, the concentration of which can increase with a process known as oxidation.
While herbal teas are not made fromC.
sinesis,that doesn’t mean that they are without tannins.
With that said, they have less tannin thanC.
sinesisand don’t undergo the same oxidation process to bring out the characteristic bitter notes.
Tannin levels between herbal teas can vary considerably.
Those that have a naturally bitter or astringent taste have higher tannin content than those that do not.
These polyphenol compounds bind to iron and prevent them from passing through the small intestine and into the bloodstream.
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National Cancer Institute.Tannin.
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