I dont know if it is directly related to AF or nutrionally depleted... most of the time they coincide with each other, but I have awful vertical ridges all over my nails.
It started with just my thumb and was ok, not terrible, over the past two years its now gone to all my nails and my thumbs look like pieces of wood lodged next to each other. I count around 15 major ones, and the rest of the nail are made up of smaller ones. My first finger was the 'last to go' and its happened quite quick over the past 4-6 months.
Some think it is directly related to a candida infection, which I do have also, but looking at photos on google for candida ones, they are ALOT worse. Mine are still white at least :)