Judgment of iron nutritional status of infants and children The iron content in breast milk is low, and the iron stored in the body supplied by the mother to the fetus through the placenta before its birth is basically used up when a full-term child is exclusively breastfed for 4-6 months after birth, requiring additional supplementation, such as the addition of fortified foods or iron-rich foods (beef, pork concentrate, animal offal, etc.), which is why the main basis for often judging iron deficiency in children is the feeding history, growth and development, the manifestation of iron deficiency anemia and the results of some auxiliary examinations such as hemoglobin and serum ferritin levels, and also the reason for the requirement to start adding supplementary foods at 6 months of age. However, in the case of preterm infants, full-term small sample infants or mothers with iron nutritional deficiency (deficiency) during pregnancy (e.g., mothers with iron deficiency anemia during pregnancy), the infant will show iron nutritional deficiency earlier. For preterm or full-term small sample infants it is recommended to start iron supplementation within 1 month after birth, 4 mg elemental iron per kg of body weight per day if there is anemia, and 1 mg-2 mg elemental iron per kg of body weight per day until 1 year of age if there is no anemia; for full-term infants, because the mother had iron nutritional deficiency during pregnancy, the infant’s iron nutritional status should also be closely monitored and iron supplementation should be started 3-4 months after birth if necessary. Determination of zinc nutritional status in infants and young children Infants and young children aged 6-24 months in the complementary feeding period are at high risk for zinc deficiency, mainly due to very rapid growth and weight gain in the first two years of life, which requires large amounts of zinc. It is generally believed that during the first 6 months of life, full-term newborns can roughly maintain the balance of zinc metabolism due to the high zinc stores in the infant’s body on the one hand and the high zinc content in colostrum on the other. However, after 6 months of age, infants need to obtain zinc supplementation through complementary food additions, and zinc-rich foods include animal fine meats, offal, and animal blood. However, preterm or low birth weight infants may have zinc deficiency early in life due to insufficient zinc reserves at birth and catch-up growth after birth, which requires more zinc than a full-term healthy infant. Children with recurrent diarrhea, infections and fever are also at high risk for zinc deficiency due to increased zinc loss and should be supplemented with zinc preparations early after birth, with 3 mg of zinc per day up to 6 months of age, increasing to 5 mg per day after 6 months of age, or 1 mg per kg of body weight per day if a significant deficiency exists. Warm tips To determine whether an infant is zinc deficient, on the one hand, we should combine feeding history, past medical history, growth and development, and on the other hand, serum zinc determination has some reference significance in determining zinc deficiency in children.