Despite efforts to improve iron supplements for iron deficiency anemia, there is no consensus on products that balance efficacy, safety and tolerability, and cost. Ferrous products are effective, but they are associated with more gastrointestinal side effects than ferric products. Ferric products tend to have lower absorption. We present results from a 12-week study that randomized 72 people with uncomplicated iron deficiency anemia to receive a ferrous iron supplement (Ferall, a combination of ferrous fumarate with ascorbic acid, folic acid, and cyanocobalamin) or a ferric iron polysaccharide complex (Niferex, ferro-glycine sulfate) plus ascorbic acid. The ferrous product was significantly more effective, the primary and secondary endpoints including changes in levels of hemoglobin and serum ferritin. There was a slightly higher frequency of gastrointestinal side effects in patients taking the ferrous product, but both supplements were well tolerated. No participant withdrew from the study because of side effects. We concluded that the ferrous product is safe and effective for use in uncomplicated iron deficiency anemia. The lack of direct comparison between single-agent ferrous fumarate and the combination ferrous product limited interpretation of results in terms of possible effects due to other components, such as ascorbic acid.