Breast milk has always been considered the most comprehensive source of nutrition for infants, but child health experts warn that exclusive breastfeeding can easily cause iron and zinc deficiency in babies, and it is recommended to add some fish puree for babies over 4 months old to avoid uneven nutrition. The iron content of breast milk is very low, 100 grams of breast milk generally contains only 0.5 mg of iron, and the zinc in breast milk is not easily absorbed by babies, so babies are most likely to be deficient in trace elements are iron and zinc, iron deficiency can occur iron deficiency anemia, zinc deficiency can cause infants slow intellectual development. For babies over 4 months old who can be fed with complementary foods, mothers should give their children some mashed fish and egg yolk every day, in addition to breastfeeding, to supplement iron and zinc for a more balanced nutritional mix; premature babies should start taking iron supplements at 2 months of age, while eating some fruit and vegetable juices to supplement vitamin E and C. Mothers should eat foods with more iron for their babies, such as egg yolk, liver, chicken and duck blood, pork, etc. For babies over 6 months old, in addition to breastfeeding, they can add iron and zinc to their diet. In addition to breastfeeding you can also add some lean ground meat to supplement iron-rich animal protein. If conditions allow, it is also possible to take some formula rich in iron and zinc.