Recently, nutritional anemia has been increasing, particularly refractory iron-deficiency anemia, which has become more common not only among older adults but also among relatively young people. Coexisting conditions such as chronic inflammatory disease, gastrointestinal disease, and chronic kidney disease can all complicate diagnosis and treatment. In many cases, appropriate treatment can improve anemia. Same as iron, copper, and zinc are proven to be absorbed from the transporter in the upper gastrointestinal mucosa, but potential zinc and copper deficiencies are increasingly being reported in cases of iron deficiency. Serum zinc deficiency is more common in cases of severe iron-deficiency anemia. This paper provides an overview of refractory iron-deficiency anemia and discusses the molecular groups involved in iron dynamics, zinc, and copper metabolism.