The importance of vitamin D goes beyond helping the body absorb and preserve calcium and phosphorus; it also has a wide range of effects, such as increasing immune function, strengthening bones and muscles, reducing falls, and lowering the incidence of cardiovascular disease, diabetes, and cancer in adulthood. There are few natural foods that contain vitamin D. Only the livers of mackerel, salmon, sardines, and mackerel contain significant amounts of this fat-soluble vitamin. In order to prevent rickets and ensure healthy growth of children, vitamin D supplementation is required from half a month of life, and the actual calcium deficiency that has been said is a lack of vitamin D. The current daily reference intake of vitamin D provided by the diet is 400 international units from 0 to 11 years old. In northern areas 6 months to 12 months to be slightly higher. If you don’t get a lot of sun in winter, or if your child is growing too fast, the amount needed should be increased and can be supplemented with 800 units per day. Many children’s specialty hospitals recommend a single vitamin D drop, with a dosage of 400 or 800 units easily adjusted at any time, or the equivalent of 600 units per day alternately on alternate days. Both familiar cod liver oil, generally contains vitamin A 1500 units and vitamin D 500 units, if you need 800 units of vitamin D can not take 2 capsules, because vitamin A will exceed, too much vitamin A will hinder the effect of vitamin D, vitamin A is also easy to supplement too much, because food can provide vitamin A original, the body can convert it into active vitamin A, vitamin Vitamin A is derived from several carotenoids, and fruits and vegetables with high vitamin A content include carrots, squash, peppers, spinach, kale, and other leafy greens, so slightly older children can get enough vitamin A from food without additional supplementation. However, for younger infants and those with recurrent respiratory infections who may have low vitamin A levels, it is still recommended to supplement with a choice of cod liver oil drops containing both A and D. Some parents choose multivitamin complex tablets, which generally contain 400 units of vitamin D as well as a sufficient amount of vitamin A. You cannot take two tablets a day, and if you need to increase vitamin D, you can add one 400-unit vitamin D tablet while taking one tablet. Many parents keep consulting different doctors in different hospitals for this purpose and are torn, because the principles of medication to prevent and treat rickets are the same, usually from half a month of life The principle of taking vitamin D is the same, usually from half a month after birth until at least 2 years of age. If you choose calcium tablets for older children, you must also choose calcium supplements containing vitamin D. Just follow this principle, yes!