Calcium is an important component of human bones. The normal growth and development of bone tissue requires an appropriate amount of calcium intake, which is very important in adolescents and children under 20 years of age, especially infants and young children. Optimal calcium intake exists for each age group, and calcium supplements should not be taken blindly in excessive amounts or overtime, and infants need calcium supplements scientifically. It is recommended that babies start taking oral vitamin D and calcium supplements from 2 weeks after birth and can stop at 2 years of age if growth and development are good. The balance of calcium in infancy depends mainly on the nutrition of calcium and vitamin D. The most important cause of calcium deficiency in infants and children is insufficient intake of vitamin D (VD). Lack of vitamin D can affect calcium absorption and lead to rickets. In the early stage, there are signs of sleep disturbance, excessive sweating, crying at night, and irritability, and in the later stage, skeletal changes such as enlarged fontanelle, delayed closure, softening of the skull, occipital baldness, chicken chest, funnel chest, rib exostosis, and O- or X-shaped legs. Since babies within 2 years of age have little outdoor exercise, it is recommended to supplement VD daily. The daily calcium requirement for newborns is about 300mg. For full-term babies who are exclusively breastfed or fed with qualified infant formula, the calcium in breast milk or formula can meet the daily physiological requirement of babies and no additional calcium supplements are needed. Vitamin D can be supplemented half a month after the baby is born, and it is recommended to supplement until 2 years old. Children between the ages of 2 and 10 years old have a slower growth rate, coupled with increased outdoor exercise and longer exposure to sunlight. As long as they eat reasonably every day and do not pick or eat partially, they should not take additional calcium supplements, except for those who are malnourished or ill. Adolescent children are in their second growth spurt and need more calcium, so they should take calcium supplements if their daily diet cannot meet this need. Calcium is essential for growth and development, but blindly taking calcium supplements will affect the absorption of other trace elements, so it is necessary to take calcium supplements scientifically and in appropriate amounts.