A circle of white arc at the front of the nail is considered to be caused by normal physiological structure, lack of vitamins or trace elements in the body. 1. Normal physiological structure: a white arc at the front of the nail is called a crescent white or half-moon mark, which is a normal physiological structure. If the arc of the crescent moon on the fingernail is large and glossy, it means that the person’s body is in a relatively healthy state. 2. Lack of vitamins or trace elements in the body: when the body lacks vitamins or trace elements, it is also easy to have white arcs on the front of the nails, often accompanied by poor luster, thin nails, easy to break and other discomforts, it is recommended to carry out a vitamin and trace element examination. Daily life or pay attention to dietary regulation, eat more food rich in vitamins and trace elements, to relieve the lack of vitamins or trace elements in the body has a certain degree of help. If cause discomfort timely consultation, follow the doctor’s instructions for treatment.