Nutritional anemia results from deficiency in either iron, vitamin B12 or folic acid, although in most areas of the world, nutritional anemia is synonymous with iron deficiency. Nutritional anemia occurs most commonly at times of heightened physiologic requirements. It is considered a major health problem in developing countries, although it is not a serious concern for the general U.S. population. Iron deficiency without frank anemia, however, does affect some segments of the U.S. population, such as pregnant and menstruating women and children.