Is your daily cuppa leaving you lower in iron?
As a tea and coffee-loving nation, we manage to get through an amazing 235 million cups every day, but could the substances in your daily cuppa be affecting your iron absorption?
It's ingrained in us from a young age that tea is the nation's favourite drink, and we often find ourselves reaching for the tea and biscuits at any given time, often sought after as a comfort drink or a relaxation aid. So how does it actually affect our ability to absorb iron, and what can we do about it?
Both tea and coffee contain chemical compounds called tannins. Tannins are naturally occurring organic substances known as polyphenols and are present in wine, beer, fruit juices, berries, pomegranates, nuts, smoked foods, legumes, some herbs and spices. These tannins could be affecting your iron absorption.
Tea and coffee's effect on iron absorption
One study has shown that tea consumption may reduce iron absorption by as much as 60% and coffee, by 50%. The tannins in both tea and coffee adversely affect iron availability, which could lead to iron deficiency anaemia.
Another study showed just 5mg of tannins inhibited absorption by 20%, 25mg by 67% and 100mg by 88%. Though some research inferred that you would have to drink more than three strong cups of tea a day to have this effect.
Other studies stated 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. Other minerals like zinc and calcium absorption may be affected, which could lead to other health issues such as brittle bones or immune system imbalances.
Taking iron supplementation is one way to prevent the possible negative effects caused by tannins, but this should be done with careful consideration. We can also choose to reduce the number of tannins we consume on a daily basis by making specific dietary changes, and reducing our consumption of tea and coffee.
So, could tannins lead to sub-optimal levels of iron, and does this mean there is a need for iron supplementation? Well, yes - particularly in the case of vegans and vegetarians that drink tea or coffee. Also, people with malabsorption issues, athletes, pregnant women or women with conditions such as endometriosis or fibroids who require extra iron may benefit.
Supplementation could also be useful for anyone who is drinking tea and coffee daily or drinking excessive amounts sporadically. Other dietary factors that need to be taken into account even if no tea or coffee is consumed, is the intake of other tannin-containing foods, or iron-rich foods such as red meat, mussels and oysters, green leafy vegetables, beans, some nuts, pumpkin seeds and tofu.
It's important to discuss with your GP your nutritional requirements for iron, and always seek professional advice before taking iron supplements as they 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.
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