I think some people just have them more than others, they can be very normal and it's not necessarily something to worry about. My mother is healthy as can be and she has always had ridges on her nails. I probably do, too, but I buff my nails regularly.
Treat yourself to a pedicure, I bet a good nail tech can tell you how common they are.
49 year old female attorney, diagnosed UC/pancolitis 1985, no surgery but much suffering.
Asacol/5ASA 6x400 mg maintenance for 20+ years; use prednisone & Rowasa for flares.
August 2008 sought care of naturopathic doctor. Food sensitivity test showed wheat/gluten, other intolerances; eliminated all wheat/gluten from my diet. Probiotics (Ultimate Flora, 50 billion), trying Curamin. Doing OK, but still have some bad days.