Why infants and children should take vitamin D supplements Because vitamin D can barely pass through the mammary glands, the vitamin D content in breast milk is very low. Since there are few foods rich in vitamin D in the diet, it is recommended that lactating mothers and infants should take vitamin D supplements when necessary to improve the nutritional status of both mother and child and to promote the absorption of dietary calcium, and to maintain a constant level of calcium in breast milk for the growth and development of the infant. Experts recommend that newborns and infants should take vitamin D. Full-term infants: 400 IU per day orally from 4 weeks after birth to 2 years of age; preterm infants, low birth weight infants, and twin (multiple) fetuses: 800 IU per day orally from 2 weeks after birth and 400 IU per day after 3 months to 2 years of age. The American Academy of Pediatrics recommends (2008 latest standard): 400 IU of vitamin D supplementation per day for all infants, children and adolescents within the first few days of life. It is well known that sunlight exposure to the skin can synthesize vitamin D. So does sun exposure make vitamin D supplementation unnecessary? Recent studies have found that sun exposure affects health. Sun exposure causes 99% of non-melanoma skin cancers and 95% of melanomas, and the association between childhood UV exposure and the occurrence of skin cancer (basal and squamous cell carcinoma, malignant melanoma) in adulthood is receiving increasing attention, with studies showing that malignant melanoma in adults is strongly associated with the degree of childhood sun exposure, and epidemiological findings indirectly confirm that the younger the age of sun exposure, the greater the risk of skin cancer, even The epidemiological results indirectly confirm that the younger the age of sun exposure, the greater the risk of skin cancer, and even more important than the total amount of sun exposure during a lifetime. Therefore, to reduce the occurrence of skin cancer, excessive sun exposure should be avoided, especially in young infants <6 months of age, so oral vitamin D supplementation is safer.