What causes vertical ridges in fingernails?

It started three years ago and began developing only in my pinky fingers and now it is spread to my entire fingers. All ten of them. Can someone shed some light on this for me? Thanks.What causes vertical ridges in fingernails?
There was a study done a few years back that tried to see if vitamin D could help with vertical ridges. I'm not sure what the results turned out to be, but - as I have them too - I started taking a 400 IU vitamin D daily (I don't get a lot of sun due to skin cancer concerns). Some of the ridges have since grown out, but it's taken a few years. Anyway, I figure the vitamin D can't hurt!What causes vertical ridges in fingernails?
Vertical nail ridges





Vertical nail ridges, which extend from your cuticle to the tip of your nail, are fairly common and often become more numerous as you age. Vertical ridges in your nails are not a health concern. Although the exact cause of such ridging isn't known, heredity may play a role.





If your fingernails change color or develop horizontal ridges, see your doctor. These changes may indicate underlying health problems, such as respiratory disease, malnutrition or even heart attack
Nature.





Perhaps like the pages of a book, the grooves on a CD, or on a record.


To my knowledge, verticle ridges in your fingernails are normal, unless a person buffs them off.





If they are splitting, then you probably need more calcium and vitamin C. If you are growing (child/teenager) you need a generous supply of these things to support your bones, nail, and hair growth.





Fresh air and sunshine are also highly recommended.





Great luck!