I've changed a number of things, and I'm not sure which one has improved my nail health. First, the diet. 90% vegan - lots of quinoa, rice and vegetables. I haven't drunk cow's milk in over a year - so much for the old teaching that milk helps your nails grow. But I started drinking almond milk, which has more natural calcium than cow's milk, about a month ago. A month isn't really long enough that I should be seeing results already from that increased calcium intake, but maybe it's possible.
Second, no nail polish. I had this weird experience where a nail polish made my fingernails hurt, after I took it off. I figured that couldn't be good. I'm not sure if it was the polish or the remover, actually. After that I decided to stop polishing my fingernails. That was about 6-10 months ago.
Third, changed to body oil instead of lotion. I think the body oil may be getting on my nails inadvertently. Since they're not polished, the oil probably soaks into my nails a little bit. I have a theory that this could be improving their resilience. Who knows?
It's cool to accidentally have long nails, is all I'm saying.