They aren't straight lines but curved too. I just noticed them a couple of weeks ago. Its just a single white curve under the nail...not the white nail bed at the bottom of each nail. I looked my my son's nails to see if he had them and he doesn't so I did a search and one site says this: Since nails are mainly made up of protein, they can immediately alert us to a lack of it in our diet. White lined bands across the nail beds can signal a protein deficiency. You can get protein from beans, oats, seeds, nuts, eggs and lean meats.
Another site says calcium deficiency. I don't know, which is why I am posting. I eat oat meal everyday..can't have eggs. I do have beans and nuts plus meat in my diet so I doubt its that. I suspect the lines..if they even really mean anything, is in the past since it takes time for those bands to develop and as my nails have grown they are moving towards the top. When I was taking an antibiotic...had three rounds due to that abscess inside of my pelvic area, I was unable to take my calcium pills because of them interacting with that antibiotics. (I can't drink milk or have any diary products...makes me sick..but I do have soy milk).
Plus all I could take in the way of vitamins was children's chewable vitamins because that is what my doctor told me to take as its easier on the stomach. Since I am now off the antibiotics I am taking normal adult vitamins (the children's vitamins didn't have very many vitamins in them) and taking my calcium pills too. Below these white bands my nails look fine. So I am hoping whatever was the cause of them is in the past now but I thought I would ask you ladies...thanks.