Inhibition of non-haem iron absorption in man by polyphenolic-containing beverages

The effects of different polyphenol-containing beverages on Fe absorption f rom a bread meal were estimated in adult human subjects from the erythrocyt e incorporation of radio-Fe. The test beverages contained different polyphe nol structures and were rich in either phenolic acids (chlorogenic acid in coffee), monomeric flavonoids (herb teas, camomile (Matricaria recutita L.) , vervain (Verbena officinalis L.), lime flower (Tilia cordata Mill.), penn yroyal (Mentha pulegium L.) and peppermint (Mentha piperita L.), or complex polyphenol polymerization products (black tea and cocoa). All beverages we re potent inhibitors of Fe absorption and reduced absorption in a dose-depe ndent fashion depending on the content of total polyphenols. Compared with a water control meal, beverages containing 20-50 mg total polyphenols/servi ng reduced Fe absorption from the bread meal by 50-70%, whereas beverages c ontaining 100-400 mg total polyphenols/serving reduced Fe absorption by 60- 90%. Inhibition by black tea was 79-94%, peppermint tea 84%, pennyroyal 73% , cocoa 71%, vervain 59%, lime flower 52% and camomile 47%. At an identical concentration of total polyphenols, black tea was more inhibitory than coc oa, and more inhibitory than herb teas camomile, vervain, lime flower and p ennyroyal, but was of equal inhibition to peppermint tea. Adding milk to co ffee and tea had little or no influence on their inhibitory nature. Our fin dings demonstrate that herb teas, as well as black tea, coffee and cocoa ca n be potent inhibitors of Fe absorption. This property should be considered when giving dietary advice in relation to Fe nutrition.