Some parents may find that their babies will involuntarily bite their nails as they grow, and this is when, as parents, they should be alert to whether their babies are deficient in zinc, iron and certain trace elements. If there is a deficiency, it can be treated with oral pediatric multivitamins. Usually, you should eat more vegetables and fruits, meat, eggs and other foods, and diversify your food to ensure balanced nutrition. Children with zinc deficiency have a special hobby called “xenophagia”, where they chew and swallow uncontrollably things they should not eat. For example, chewing nails and clothing. It can be accompanied by loss of appetite, abnormal taste, indigestion, chronic diarrhea, or light hair color. Children with iron deficiency may also exhibit xenophagia and may bite their nails from time to time. They may also exhibit fatigue and weakness, delayed physical development, and, in severe cases, anemia. If you find these symptoms in your baby, seek medical attention and take iron supplements in a timely manner. Some children’s fingernail biting is not related to micronutrient deficiency, but is due to mental tension, stress, and other reasons. Therefore, it is necessary to consider many aspects in order to understand the reasons why children bite their fingernails.