Vitamin A deficiency, also known as toadermatosis, is a nutritional disorder caused by vitamin A deficiency. Typical clinical manifestations include dry and rough skin, conical follicular keratotic papules on the extremities, night blindness, and dry and softened corneas. This disease is no longer seen as a typical serious disease under the condition that the living standard of the country has improved and the importance of pediatric insurance has increased. The reason why Uncle Chen has to popularize this disease here is that vitamin A deficiency will lead to low immune function when there is no typical clinical manifestation in the early stage, or even when there is insufficient stock in the body, and it is easy to get respiratory and gastrointestinal infections repeatedly, and it is not good to get old. Families and even doctors are often misled to see recurrent infections without knowing that vitamin A deficiency is behind them, resulting in unnecessary overmedication. Common causes of vitamin deficiency: 1. Not enough is given. Vitamin A does not enter the fetus through the placenta, breast milk, the mother wants to give can not be given, after birth, if you can not add supplemental food to vitamin A, it is very easy to appear vitamin A deficiency. 2, no absorption. Vitamin A is a fat-soluble vitamin, it wants to enter the body from the small intestine must have a “nobleman” to help, that “nobleman” is bile salts, and bile salts have to have the invitation of fat, so you want to vitamin A absorption, to eat some fat at the same time. 3, the consumption of large. Vitamin A mainly exists in the coffers of the human liver, so any disease that can affect the function of the liver, will affect, the vitamin A stores. Some consuming infectious diseases, especially measles, scarlet fever, pneumonia and tuberculosis can steal a lot of vitamin A causing vitamin A deficiency. Vitamin A deficiency is easy to prevent, and the method is simple and feasible, just pay attention to two points: 1, routine supplementation of cod liver oil, one month after birth to start taking Icosan, one capsule per day until 1.5 to 2 years old. 2, add supplementary food, vitamin A-rich foods are: pig liver, chicken liver, lamb liver, milk, egg yolk, carrots, fish eggs, milk, pea seedlings, goldenrod, alfalfa, red sweet potatoes, peppers, river crabs, eels, spinach, leeks, capers, lettuce leaves, goldenrod or fruits such as apricots, mangoes and persimmons.