Gray hair can be caused by a lack of trace elements such as iron and zinc, or by mental reasons such as stress, or by normal aging. When there is a lack of iron, zinc and other trace elements, it will cause a reduction in the amount of melanin in the hair follicle, can not provide enough melanin for the hair, plus these elements will also lead to the decline in the function of the hair follicle, and then there will be a situation of gray hair, need to be determined through the trace element examination. In addition, a long time in a high-pressure state of tension or excessive brain state, will also have an impact on the melanin synthesis, so that the tyrosinase activity is reduced, thus appearing to have gray hair, it is recommended that balanced nutrition in life, and at the same time to learn to relieve stress, keep the mood of pleasure and relaxation. There are many reasons for long gray hair, need to be combined with the specific causes, through diet, mental relaxation to improve.