tannins
3 interactions related to tannins
black tea + iron
Polyphenols (tannins) in black tea bind non-heme iron in the gut lumen to form insoluble iron-tannate complexes, blocking absorption. Inhibition of non-heme iron uptake from a meal can reach 79-94% when black tea is consumed with food.
peppermint tea + iron
Peppermint tea is rich in polyphenols (particularly rosmarinic acid) and tannins that bind non-heme iron in the gut, forming insoluble complexes that cannot be absorbed. Controlled studies show peppermint tea can reduce non-heme iron absorption from a meal by up to 84%.
oolong tea + iron
Oolong tea sits between green and black tea in polyphenol oxidation and contains substantial tannins and catechins that bind non-heme iron in the gut to form insoluble iron-polyphenol complexes. Drinking oolong tea with meals reduces absorption of dietary and supplemental non-heme iron.