Since before Christmas, unaware then of any B12 deficiency, I was told I probably wasn't methylating properly. I started on a small dose of methylcobalamin and methyl folate. I've always had awful nails, breaking and wearing down very quickly, but noticed that my thumb nails were becoming very strong. About a month ago the B12 deficiency came up and sublingual doses of methylcobalamin were started and now the nails on my index fingers are a lot better. Is this the way it goes, working its way from thumbs to little finger? I hope so! It's really fascinating.