title: Vitamin D and rheumatoid arthritis: comment on the letter by Nielen et al.
authors.forename: Maurizio
authors.initials: M
authors.lastname: Cutolo
authors.forename: Kati
authors.initials: K
authors.lastname: Otsa
authors.forename: Maria
authors.initials: M
authors.lastname: Yprus
authors.forename: Bruno
authors.initials: B
authors.lastname: Seriolo
mesh_terms: D001172:Arthritis, Rheumatoid / Q000097:blood / Q000209:etiology*; D016022:Case-Control Studies; D004957:Estonia; D005260:Female; D006801:Humans; D007558:Italy; D008875:Middle Aged; D012621:Seasons; D012720:Severity of Illness Index; D013472:Sunlight; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood / Q000502:physiology*; D014808:Vitamin D Deficiency / Q000097:blood / Q000150:complications*
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D