What are some causes of not being able to absorb iron?

Iron absorption : Coffee and tea consumption at the time of a meal can significantly decrease iron absorption. Tea can cause iron absorption to drop by 60 percent and coffee can cause a 50 percent decrease in iron absorption. Phytates in some legumes and grains, phosphates in cola drinks, some prome proteins in soybean may affect iron absorption. Whereas vit. C enhances iron absorption from GIT.

Inflammation: Inflammation in the intestines caused by celiac disease or other conditions feature a protein called hepcidin that affects the ability of the body to absorb iron and utilize it. Hepcidin also inhibits ferroportin