Calcium is an important nutrient for the human body. The normal growth and development of bone tissue requires an appropriate amount of calcium intake, especially for infants and children is very important. Optimal calcium intake exists for each age group, and calcium supplements should not be taken blindly in excessive amounts or overtime, and infants need scientific calcium supplementation. 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 young children is insufficient intake of vitamin D (VD). Lack of vitamin D can affect calcium absorption and lead to rickets. 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 infants who are exclusively breastfed or fed with qualified infant formula, the calcium in breast milk or formula can meet the daily physiological requirement of infants and no additional calcium supplementation is needed, but vitamin D supplementation is needed to promote calcium absorption and prevent vitamin D deficiency rickets. Babies can take vitamin D supplements half a month after birth, and it is recommended to supplement until 2 years old. Children under 6 months of age do not need additional calcium supplements as long as they have a normal daily intake of breast milk or formula and vitamin D. For children over 6 months of age, a sensible diet, with attention to calcium supplementation, and generally only VD supplements are sufficient. If your child is really deficient in calcium or suffers from certain diseases, you can take calcium supplements and choose the right one according to the severity of calcium deficiency. Calcium is essential for growth and development, but blindly supplementing calcium will inevitably affect the absorption of other trace elements, so it is necessary to supplement calcium in the right amount according to the age science.