Iron deficiency-related anemia is the most common nutritional deficiency disorder in the world, mainly affecting children, women and older adults in underdeveloped countries. To combat iron deficiency, inorganic forms of iron (such as ferrous sulfate) are often used as an iron supplement. One big problem is that high levels of this kind of iron supplement produce negative health effects. This includes diarrhea, changes in the bacteria in the gut, as well as increased severity to malaria in young children in countries with high rates of that parasite.