The 40-year-old man beard white, may be a normal aging performance, may also be related to the lack of trace elements, and may even be related to vitiligo and other diseases. 1. physiological factors: 40 years of age, the human body’s functions began to gradually decline, a small amount of white hair may be a normal aging performance, without special treatment. 2. trace element deficiency: trace elements are important substances that maintain the structure and function of the human body, and can affect hair growth and color, which copper, zinc, iron, phosphorus and other trace element deficiencies, may affect the color of the hair. 3. Vitiligo: this is an acquired pigment deficiency disease, with genetic and autoimmune factors related to the clinical mainly manifested in the skin white patches, white patches in the region of the hair can also be white. Because of the cause of more, the specific circumstances need to ask the doctor for an interview.