Yellow hair is not necessarily a lack of micronutrients, it may be caused by birth or improper hair care, or it may be a pathological condition, such as phenylketonuria and malnutrition. 1. Many people are born with somewhat yellowish hair, which may be related to the yellowish hair color of their parents, and is a natural phenomenon that requires no treatment. 2. People who often wash their hair with poor quality or alkaline shampoo or soap, or who often perm or dye their hair. The hair structure will be easily damaged and the hair will be dry and yellow. Some people will hurt the scalp hair root, easy to lead to the new growth of hair thin, dry, yellow. Many people choose the right scalp conditioner, shampoo, daily massage scalp after dry and yellow symptoms can be improved. 3. Phenylketonuria is an autosomal recessive disease that occurs in the offspring of consanguineous marriages. Due to the blockage of phenylalanine metabolism, a large number of harmful metabolites are produced, which can easily lead to brain damage and other diseases. In addition to yellowing of hair, they are prone to mental retardation and ratty-smelling urine. Avoiding consanguineous marriage can significantly reduce the incidence of phenylketonuria. 4. Children whose bodies are deficient in trace elements such as zinc and copper may show symptoms of yellowing of hair. It is usually seen in children with food accumulation or severe picky eating or lack of nutrient sources. Improvement of dietary habits and balanced diet types can usually recover on their own. If yellowing of the hair occurs, it is recommended to consult a doctor in time to find out the cause of the disease.