Vitamin A deficiency is caused by chronic vitamin A deficiency, which refers to all effects of vitamin A deficiency on growth, immunity, embryogenesis, other body systems and survival. Vitamin A deficiency is recognized by WHO as one of the four major nutritional deficiencies in the world. The fatality rate of children with severe vitamin A deficiency is ≥50%. Pregnant women and children are susceptible to vitamin A deficiency.

　　 Vitamin A deficiency can be mainly caused by the following conditions: improper diet, digestive system diseases, wasting diseases, hypothyroidism, diabetes and zinc deficiency.

　　 For the general population, the best way to prevent vitamin A deficiency is to eat foods rich in vitamin A. Vitamin A is a fat-soluble vitamin. Natural vitamin A exists only in animal foods. The carotene contained in plants enters the body and can be converted to vitamin A in the liver.

　　 Due to the high absorption rate of vitamin A in animal foods, WHO recommends that at least 40% of the vitamin A supplied to the body daily comes directly from animal foods. Among animal foods, the highest vitamin A content is the liver. Lamb liver and beef liver contain about 50,000 IU of vitamin A per 100g. Milk, butter, cheese and eggs have a medium vitamin A content, while beef, lamb and pork The vitamin A content is low.

　　Vegetable-rich vegetables or fruits in vegetable foods include pumpkins, carrots, dark green leafy vegetables, potatoes, mangoes, apricots and tomatoes.

　　For infants, breast milk is a good source of vitamin A. It should vigorously promote exclusive breastfeeding within 6 months after birth, and continue breastfeeding until 2 years old, and mothers should also eat more Foods rich in vitamin A.