<Li> Increased loss of iron (usually through loss of blood). </Li> <Li> Nutritional deficiency . This can result due to a lack of dietary iron or consumption of foods that inhibit iron absorption, including calcium, phytates and tannins . Black tea steeped for long has high tannins . </Li> <Li> Inability to absorb iron: A common cause of iron deficiency is the widespread use of acid reducing medications, the strongest of which are proton pump inhibitors (PPIs) such as omeprazole . </Li> <Li> Damage to the intestinal lining . Examples of causes of this kind of damage include surgery involving the duodenum, or diseases like Crohn's or celiac sprue which severely reduce the surface area available for absorption . </Li>

A nutrient that forms important structures in the body