Nutrients are defined as not only having nutritive values of participating in the metabolism and building the structures of cells but also being safe for human body. Nutrients are divided into two types, macronutrient and micronutrient, according to the proportion of the human body. Commonly, micronutrients include trace elements (trace mineral) and vitamins (complex organic molecules). It is difficult to demonstrate micronutrient deficiency because the symptoms are varied and laboratory analyses are limited. Since parenteral nutrition became an established therapy, micronutrient deficiency syndromes are being identified more frequently and emphasize the importance of a complete nutritional support. In this article, we review various specific trace element deficiency states such as zinc, copper, and selenium and briefly discuss the use of dietary supplements.