Iron sources used in food fortification and their changes due to food processing.

The effect of food processing on the biological availability of iron in iron-fortified foods is critically reviewed. Studies on changes in the chemistry of the iron in processed foods are examined. Various iron sources currently used in food fortification in the U.S. are defined with emphasis on their biological availabilities under various conditions. The availability of iron in foods depends upon numerous factors, most of which are not fully understood. A factor which is often overlooked is the interaction of the iron with the food during events such as cooking or processing. Chemical changes in the iron compounds occur which may correlate with changes in the biological availability.