Cod liver oil-supplementary food for infants and young children

　　 cod liver oil is fat extracted from cod liver and contains a lot of vitamin A and vitamin D, so the general medicine is called "vitamin AD capsule" (of course, there are also (Drops, soft capsules and other dosage forms, and some products named after trade names or trademarks). Vitamin A and vitamin D are nutrients that play a key role in the development of infants and young children.

　　Adequate vitamin A is not only an important guarantee for the development of children''s skeletal system and reproductive system, but also affects the child''s respiratory system immunity, skin health and visual formation. Lack of vitamin A can cause children to be short. In fact, the main nutritional cause of short stature in infants (1 to 3 years old) and preschool children (4 to 6 years old) is vitamin A deficiency. Vitamin A deficiency, even a "subclinical" deficiency (not obvious deficiency), can cause repeated respiratory infections in infants and young children. The role of vitamin A is so extensive and important, and the consequences of vitamin A deficiency are so serious that we can say that for infants and children, vitamin A is the most important vitamin and is worthy of being "A". Vitamin A is mainly derived from animal liver, meat, egg milk, etc., and can also be converted from β-carotene in vegetables and fruits. For infants and young children, cod liver oil is one of the most reliable sources of vitamin A.

　　Vitamin D mainly regulates calcium metabolism, promotes calcium absorption in the intestine, promotes calcium utilization in bones, and reduces calcium excretion in the kidneys—in short, vitamin D is essential for calcium metabolism. Vitamin D deficiency (as well as calcium deficiency) is the key cause of rickets in infants and young children, and rickets is currently the most common one among infants and young children with nutritional deficiencies, and there is still a high incidence rate. Early symptoms include irritability, night terrors, crying, sweating, occipital alopecia and other neurological symptoms. In severe cases, there will be bone changes such as square skull, rib beading, thoracic deformity, limb deformation, and usually leave sequelae. Vitamin D food sources are very limited, and it is difficult to meet the needs of ordinary food. It mainly depends on the skin to synthesize itself under the sunlight (ultraviolet rays). Generally, if you expose your face and expose your forearms for 2 hours, the synthetic vitamin D can meet the needs of the day. Obviously, for infants and young children in the north, especially in most parts of the northeast, it is difficult to expose the face and expose the forearms to the sun for 2 hours, especially in the cold winter and spring season. Sun exposure through glass, wearing clothes, and insufficient sunlight cannot ensure the synthesis of sufficient vitamin D. For this reason, it is now considered that infants and young children taking cod liver oil is the most reliable way to obtain vitamin D and prevent rickets.

In summary, it is generally advocated that children in the north take cod liver oil preparations from the full moon until they are 2 or 3 years old. At present, some pediatrics and nutrition textbooks have recommended cod liver oil as a supplementary food for infants and young children. However, it should be emphasized that overdose of vitamins A and D can cause poisoning, because the poisoning caused by taking too much cod liver oil occurs from time to time. Therefore, when taking cod liver oil preparations, it is necessary to grasp the appropriate dosage. According to the Dietary Nutrient Reference Intakes (DRIs) launched by the Chinese Nutrition Society in 2000, the appropriate daily intake of vitamin A for infants and young children (under 3 years old) is 1320~1500IU (international unit), and the recommended intake of vitamin D is 400 IU (International Unit). When taking cod liver oil preparations, it is best to choose products specifically designed for infants and young children. The dosage is generally appropriate. When the single dose of cod liver oil preparation used is relatively large, the supplement method of taking once a day can be used. Please ask an experienced pediatrician, maternal and child health doctor, and dietitian for specific conversion methods or dosage methods to ensure safety. Do not waste food because of choking (refusing to take it because of fear of poisoning), or eat blindly.