Vitamin D is necessary for correct growth and bone development in children. It also promotes bone and tooth health and supports correct muscle function. In addition, vitamin D helps to ensure efﬁ cient absorption and use of calcium and phosphorus in the body, to maintain normal blood calcium levels and correct immune system function. Between the 6th and 12th month of life, the recommended vitamin D supplementation dose is 400-600 IU/day, depending on the amount of vitamin D supplied with food. The recommended vitamin D supplementation dose for children aged above 1 year is 600-1000 IU/day, depending on body weight, between September and April or all year round, if effective skin synthesis of vitamin D in the summer season is not ensured.