Tea contains tannins, chemical compounds found in plants. Tannins are used by the leather making industry to tan leather, as well as to influence the taste of wine.
Tannins also bind to iron in a process called chelation. If there was iron present in your food you would have found a black solid (known as a precipitate). You need iron to make red blood cells. If you drink too much tea you may stop iron in your food being absorbed by your body!
Drinking tea is good for you, but try to avoid drinking tea when eating if you know you're low in iron.
