==Special Precautions of Tannins==
* Don't confuse with tannic acid : The main cause of confusion concerning tannins is that they're often mistakenly believed to be associated with tannic acid which is used for tanning leather, when this is not the case. Tannic acid is often extracted from oak leaves and has a completely different chemical makeup than polyphenols, so despite the fact that you may have heard that tea tannins (polyphenols) can be used for tanning leather, this simply is not true.
* Tannins can discolor teeth. This is one reason why dental specialists advise on limiting coffee and tea intake.
* Tannins can also impede the body’s ability to absorb iron which may adversely affect an otherwise balanced diet. If, for instance, you are in the habit of drinking coffee or tea while having your meal, the tannins in your drink can retard your body’s absorption of iron from the vegetables in your meal. There is a way though to counter the effect, or at least lessen it, through lemon or milk added to your brewed beverage. Another suggestion is to drink coffee or tea between meals – not during mealtime itself.