Is it true that green tea prohibit the absorption of iron therefore is not recommended to drink during menstrual period?

Not a real concern: Tannins in tea bind iron in the gut and interfere some with its absorption. Many other substances do the same thing. It's important you have enough usable iron in your diet, and tea isn't going to make or break your health. Iron is absorbed for long-term and it doesn't matter what time of month it is. Your personal physician or evidence-based nutritionist is your best guide here.

Traditional Chinese : Medicine recommends against drinking green tea during a female's menstrual period. It is reported that during menstruation women may lose 18 to 21 mg of iron in association w blood loss. The tannins in green tea can adversely impact absorption of iron through intestinal mucosa. The tannic acid may also ^ possibility of constipation.