What is vertical grain on thumbnail?

There are vertical lines on the fingernail that may be caused by the following conditions: 1. Lack of nutrition in the body: If the body lacks nutrients, especially iron and vitamin A, it will cause the fingernail to show vertical lines. In this case, appropriate iron supplements or eat more foods rich in vitamin A such as pumpkin, carrots, corn, etc. 2. Long-term mental stress, severe lack of sleep: Due to excessive work, the body and brain are in a state of fatigue, resulting in vertical lines on the thumbnail, at this time you can pay more attention to rest. 3. Diseases: such as pancreatitis, rheumatism, etc. can also lead to vertical lines on the thumbnail.