According to Chinese medicine theory, the nail crescent is related to physical health and can be used to determine whether a person’s heart is functioning well or whether there is an abundance of qi and blood. From the perspective of Chinese medicine, a person with a large number of white crescents on the nail, covering one-fifth of the area and with a milky white color, has sufficient heart energy and smooth blood circulation; however, a person with a small number of white crescents, covering less than one-fifth of the area or none, with a light color or even a purple-black color, has weak heart energy and poor blood circulation, and may have some Chinese medicine diseases in the body. However, modern medicine believes that there is no direct correlation between the crescent on the nail and the health of the body. The nail is formed by the synthesis of keratin from the methyl group in the body, but the synthesis of keratin from the methyl group takes some time, and there are some fast and some slow, and the new keratin cells of the methyl group will show a light milky white color on the nail, which is what we call the crescent. The size of the nail crescent is mainly related to the growth rate of the nail, the congenital nail matrix grows back, or the nail growth rate is slow, etc., will make the nail crescent can not be revealed. The number and size of adult nail crescents may vary, so you can’t judge health simply by the crescents. However, there are some people who do not have crescents on their nails, which may indicate malnutrition or hypothyroidism, in addition to the slowing down of methyl synthesis due to advanced age. This affects the slowing down of metabolism in the body, resulting in slowing down or impairment of methyl synthesis of keratin, when the crescent is associated with the health of the body. If only the nail crescent disappears or decreases, it will not have a significant effect on the human body. However, if the surface of the nail crescent appears significantly dark and painful, and at the same time there are symptoms such as general weakness, coldness and loss of appetite, it is recommended to go to the hospital for further examination in order to avoid adverse consequences.