I don't have an issue with my fingernails except they get damaged from working with a lot of products. My toenails all of a sudden have been bad for the last year or so. It can mean a deficiency in your diet and long ago they used to say to have gelatin. I tend to not want that, but if it continues I may try other things. When you say peeling, what would you exactly mean /brittle too. I have been using nightime deep facial moisturizers recently on the skin surrounding it because that was affected too.

My nails peel too. I haven't found any "magic" product though but they seem to peel less if I keep them very moisturized. No one nail/cuticle oil seems any better than the others although I really do like Burt's Bees Lemon Butter Cuticle Cream. I have had some pretty good results with putting regular olive oil in a small shallow bowl, microwaving it till its warm and then soaking my nails and cuticles in it. I also try to keep a clear coat of strengthener on them in the winter and that does help some.

Have you tried using a glass nail file, instead of the traditional kind? My nails used to split and peel too, but since i switched to the glass nail file I haven't had any peeling. Filing in just one direction, instead of back and forth helps too.