Ridged nails have vertical or horizontal lines across the surface.
Adults generally have vertical ridges which increase with age, yet dehydration or unhealthy blood supply may also cause the appearance of vertical lines.
The appearance of horizontal lines are usually thought to be caused by the lack of nutrition and zinc. They also occur during preganancy or high fevers.
Nails grow at a rate of 3mm to 4mm per month. Therefore if you find horizontal lines appearing on your nail at about 3mm from the nail root, it would suggest that there was an internal change of the body about 1 month ago.
For both horizontal and vertical ridges, we encourage a healthy diet and lifestyle. If they appear, the application of a buffer (nail polish) will smooth the ridges.
Prevention
A consistent healthy diet and lifestyle is important. People who are prone to dehydration may find it effective to apply some cream. However, for vertical rides, the cause is age which is difficult to prevent.
Furthermore, for horizontal ridges, their appearances symbolise an internal change of the body. If they continue for a prolonged period of time you may need to visit a medical professional.