Symptoms of selenium deficiency in children include the following: First, low immunity, growth and developmental delay. Secondly, they can suffer from keshan disease, with symptoms of fatigue, panic, pallor, accelerated heart rate and even arrhythmia. Third, macroglossia, manifested as coarse bone joints of the limbs and short stature. Fourth, the body lack of iodine, appearing goiter. Fifth, the lack of selenium can also affect the development of the nervous system, manifested as intellectual developmental disorders, because selenium is an essential trace element, involved in a variety of selenium-containing enzymes and selenium-containing protein synthesis.