Since I learned that my iron stores were extremely low last year, the topic of iron absorption has been of great interest to me. I love both coffee and tea, but I was concerned when I heard that both could prevent me from absorbing as much iron from meals.
While this is not necessarily a bad thing for everyone — in contrast, high iron levels are a risk factor for some (men in particular) — but this could present a problem for those who have low iron.
For example, this study looked at the effect of different beverages on iron absorption when consumed with a hamburger. When the meal was served with tea, there was a 62 percent reduction of iron absorbed; with coffee, a 35 percent reduction. Orange juice increased iron absorption by 85 percent, while pure alcohol and wine increased absorption just slightly (though wine with a high iron content significantly increased the amount of iron absorbed). Milk and beer had no effect, and Coca-Cola increased absorption slightly.
So yes, tea and coffee had a definite effect on iron absorption, but here is the catch — this was regarding non-heme iron. Heme iron is iron from meat sources. Non-heme iron is from plant sources. In other words, those who are depending on plant-based foods for their iron should be especially careful.
Another study found that phenolic-rich extracts from both rosemary and green tea reduced iron absorption from non-heme sources.
Does this mean that coffee and tea are bad for you? In my opinion, no. As someone who struggles to keep my iron levels normal, I simply make sure that I don't consume coffee and tea with my meals or near the time when I take my iron liquid supplement (since it is a non-heme iron source).
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