“Tea, particularly black tea, contains compounds called tannins,” explains nutritionist Nichola Ludlam-Raine.“Tannins are a type of polyphenol that bond to iron in certain foods, inhibiting its absorption in your digestive system.” That’s particularly the case with plant-based (non-heme) iron sources, she says, although tannins can also impact the absorption of heme (animal) iron too.

“For individuals who are anaemic or have low ferritin levels, paying attention to the timing of tea consumption can be crucial. It’s generally recommended to wait at least an hour after an iron-rich meal or iron supplement before drinking tea. Similarly, try to have tea at least an hour before your next iron-rich meal or supplement. This gap helps to ensure that the tannins in the tea don’t interfere with the iron absorption from your meal or supplement.”

She does flag, however, that the impact of tea on your iron absorption is going to vary from person to person. It depends on your own health, the type of iron in the supplement and wider dietary habits.

Tea stops you from absorbing iron – one nutritionist explains the link between tea and iron deficiency