Just wanted to share. My nails had been peeling for a little over a year. Nothing helped and I never could figure out why. No amount of water drinking helped. We happened to be giving our dogs a salmon oil supplement and their hair was so shiny. I thought if it worked for them maybe it would make my hair shiny too. I got NOW brand Salmon Oil for humans 
and about 2-4 weeks later my nails just started looking gorgeous. I am not sure how long it took because I had basically given up on them and then one day I just noticed how awesome they looked. And I am not trying to push that brand. It's a well known brand and I don't think they need my help. But its working for me. I am sure other quality salmon oils would work for you too. Good luck to those with nail issues.
and about 2-4 weeks later my nails just started looking gorgeous. I am not sure how long it took because I had basically given up on them and then one day I just noticed how awesome they looked. And I am not trying to push that brand. It's a well known brand and I don't think they need my help. But its working for me. I am sure other quality salmon oils would work for you too. Good luck to those with nail issues.