Normal skin color is composed of four biological pigments, of which the main ones are brown melanin, yellow carotene, red oxyhemoglobin, and blue reduced hemoglobin. Melanin is mainly distributed in the epidermis and is the main determinant of skin color. The increase of melanin in the body is mainly related to various factors acting on melanocytes, tyrosinase activity, genetic factors and hormonal regulation can affect the melanin deposition in the body, the main hormones are melanocyte stimulating hormone, adrenocorticotropic hormone and estrogen, etc. Ultraviolet light from the sun can also increase skin pigmentation. There is also a relationship with age, as the number of melanocytes decreases with age and the amount of melanin produced decreases. Inflammation of the skin may increase the secretion of melanocytes, causing post-inflammatory hyperpigmentation spots. Vitamin B complex and folic acid can promote oxidation, which can increase melanin.