Black Tea Interactions

Black tea is rich in polyphenols (tannins) that bind iron in the digestive tract. When the two are taken together, less of the iron your body needs gets absorbed.

Black tea contains antithiamine factors - polyphenols such as tannins and chlorogenic acid - that can oxidise thiamine (vitamin B1) into biologically inactive forms in the gut before it is absorbed. Heavy habitual tea consumption has been linked to lower thiamine status, mainly in people whose dietary B1 intake is already marginal. For most well-nourished adults the effect is modest.