The appearance of black vertical lines on the nails is mostly considered to be due to prolonged physical labor and irregularity in the body’s routine. Often malnutrition, lack of vitamins and minerals. The above situation requires the patient to timely regulate the body, replenish the relevant elements, and over time will be self-healing. It is also possible that the liver and kidneys are weakened and toxins are deposited. You need to go for a relevant medical examination, if there is no substantial lesion, you can usually regulate the liver and kidneys, you can eat more liver tonic food, such as high protein food, fish and seafood. Kidney food is sea cucumber, shrimp, eggs and so on.