We are a nation of tea and coffee lovers and manage to get through around 235 million cups of the stuff every day, but could the chemicals in your daily cuppa be inhibiting your iron consumption?

Tea and coffee contains chemicals called tannins. Tannins are naturally occurring organic substances also known as polyphenols. They are present in wine, beer, fruit juices, berries, pomegranates, nuts, smoked foods, legumes and some herbs and spices and they could all be affecting your iron absorption.

Some studies have shown that tea consumption may reduce iron absorption by as much as 60% and coffee reduces its uptake by 50%.  The tannins in both tea and coffee adversely affect iron availability , which could lead to iron deficiency anaemia.

Some studies showed just 5mg inhibited absorption by 20%, 25mg by 67% and 100mg by 88%, whereas some research suggested you would have to drink more than 3 strong cups of tea a day to have any effect. Other studies state that non haem iron (vegetable sources) absorption is only affected by tannins and haem iron (meat sources) are not affected, but this does not take into account a person’s individual absorption capabilities.

Tannins can cause mal-absorption of other minerals like zinc and calcium, which may lead to other health issues indirectly such as brittle bones and immune system imbalances.

Taking iron supplements is one way to reduce the detrimental health effects caused by tannins. Alternatively we could choose to reduce the amount of tannins we consume on a daily basis by making suitable dietary changes and reducing our intake of tea and coffee.

So are tannins leading to sub-optimal levels of iron and does this mean there is a need for iron supplementation?  Well, yes definitely in the case of vegans and vegetarians that drink tea or coffee. Supplementation would also be useful for anyone who is drinking tea and coffee daily, or drinking excessive amounts sporadically. Other dietary factors also need to be taken into account even if no tea or coffee is consumed, such as intake of other foods.

Always check with your GP before taking iron supplements as it can be harmful if not monitored. If taking any iron supplements, be sure to take them separately from your cup of tea as this may affect absorption.