Therefore, eating beef and beans, for example, is good for providing adequate absorption of both types of iron. Vitamin C also promotes iron absorption. This is true for both heme and nonheme iron. It is, therefore, beneficial to consume citrus fruits or juices, which are high in vitamin C, with foods that contain iron. Phytic and tannic acids are two food components that, when consumed in large amounts, prevent the absorption of iron.
Phytic acid is found in rye bread and other foods made from whole grains.
Phytic acid is also found in nonherbal teas. Tannic acid is found in commercial black and pekoe teas, coffee, cola drinks, chocolate, and red wines. However, iron supplements should only be taken when there is a true deficiency of iron and only under medical supervision. General multivitamins often have iron and other minerals added to them in moderate amounts. If otherwise healthy, this amount of iron is probably not harmful.