I've had these for a few years now.
In September my thumb became infected just at the base of the nail. It affected my nail really badly, and now I think it's going to take the best part of a year to be OK again.
I had no idea the two were probably related, but after doing some digging around, it seems that they are.
I've been taking collagen supplements for a month now, and the difference it's made to my nails already is absolutely amazing.