The American Academy of Pediatrics has now updated its nutritional guidelines for children’s bone health – adequate calcium intake through daily meals is the best way to ensure bone health in children. During infancy, breast milk or infant formula is the primary source of calcium for children. Although formula-fed children have higher serum calcium concentrations than breastfed children, there is no data to suggest any benefit from this phenomenon. Between 70% and 80% of the daily calcium requirement should be consumed from milk or other dairy products. In general, 230 ml of milk provides 300 mg of calcium, which is comparable to the calcium provided by 1 cup of yogurt or 45 g of cheese. Vegetarian foods such as leafy greens, bean pods, fruit juices, nuts, and nutritionally fortified oatmeal also contain highly bioavailable calcium, but it is difficult to meet the day’s requirements if the diet is simply vegetarian. And a low protein diet will reduce the body’s retention of calcium. Some alternatives to milk, such as soy milk and almond milk, even when fortified with calcium, provide less bioavailable calcium than the same amount of milk. The meta-analysis suggested that taking calcium supplements did not improve bone density in the lumbar spine and femoral neck in children, and only marginally improved bone density in the upper extremities. Therefore, the researchers concluded that calcium supplements do not reduce the risk of fracture in normal healthy children. Vitamin D is essential for calcium absorption, and without vitamin D (VD), only 10-15% of dietary calcium is absorbed. The current recommended intake of vitamin D is 400 international units (IU)/day up to 1 year of age and 600 IU/day from 1 year of age to adolescents. Although VD can be converted by sunlight exposure to the skin, the widespread use of sunscreens and the reduced outdoor activity of children actually reduce the effect of sunlight. In addition, areas with dimensions above 33 degrees will have significantly less holiday sunlight in the fall and winter, even with adequate outdoor time. Breastfed infants can be fed without VD supplementation, provided that the lactating mother has a daily intake of 6000 IU of vitamin D. Otherwise, breastfed infants should start vitamin D supplementation within a few days after birth. Additional VD supplementation is not necessary when more than 1000 ml of infant formula or VD-fortified milk can be applied daily. For children in certain pathological states, such as obesity, use of antiepileptic drugs , children receiving glucocorticoids, antifungals, antiviral therapy, although there is no recommended dose, it is considered that the daily intake of VD should be 2-4 times of 600 IU.