title: High plasma levels of vitamin C and E are associated with incident radiographic knee osteoarthritis.
abstract: BACKGROUND
  Previous studies suggest that the antioxidants vitamins C and E may protect against development of knee osteoarthritis (OA). We examined the association of circulating levels of vitamin C and E with incident whole knee radiographic OA (WKROA).
  
  
  METHODS
  We performed a nested case-control study of incident WKROA in MOST, a cohort of 3,026 men and women aged 50-79 years with, or at high risk of, knee OA. Incident cases were knees without either tibiofemoral (TF) or patellofemoral (PF) OA at baseline that developed TF and/or PF OA by 30-month follow-up. Two control knees per case were selected from those eligible for WKROA that did not develop it. Vitamin C and E (alpha-tocopherol) assays were done on baseline supernatant plasma (PCA) and serum samples, respectively. We examined the association of gender-specific tertiles of vitamin C and E with incident WKROA using logistic regression with GEE, adjusting for age, gender, and obesity.
  
  
  RESULTS
  Subjects without WKROA at baseline who were in the highest tertile of vitamin C had a higher incidence of WKROA [adjusted OR = 2.20 (95% CI: 1.12-4.33); P-value = 0.021], with similar results for the highest tertile of vitamin E [adjusted OR = 1.89 (1.02-3.50); P-value = 0.042], compared to those in the lowest tertiles. P-values for the trend of vitamin C and E tertiles and incident WKROA were 0.019 and 0.030, respectively.
  
  
  CONCLUSIONS
  Higher levels of circulating vitamin C and E did not provide protection against incident radiographic knee OA, and may be associated with an increased risk of knee OA.
authors.affiliation: Division of Rheumatology, UCSF, San Francisco, CA, USA.
authors.forename: R K
authors.initials: RK
authors.lastname: Chaganti
authors.affiliation: Department of Epidemiology and Biostatistics, UCSF, San Francisco, CA, USA.
authors.forename: I
authors.initials: I
authors.lastname: Tolstykh
authors.affiliation: NIHR Musculoskeletal BRU, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, UK.
authors.forename: M K
authors.initials: MK
authors.lastname: Javaid
authors.affiliation: Clinical Epidemiology Research and Training Unit, Boston University School of Medicine, Boston, MA, USA.
authors.forename: T
authors.initials: T
authors.lastname: Neogi
authors.affiliation: Department of Epidemiology, University of Iowa, Iowa City, IA, USA.
authors.forename: J
authors.initials: J
authors.lastname: Torner
authors.affiliation: Division of Clinical Immunology and Rheumatology, University of Alabama at Birmingham, Birmingham, AL, USA.
authors.forename: J
authors.initials: J
authors.lastname: Curtis
authors.affiliation: USDA Human Nutrition Research Center on Aging at Tufts University, Boston, MA, USA.
authors.forename: P
authors.initials: P
authors.lastname: Jacques
authors.affiliation: Clinical Epidemiology Research and Training Unit, Boston University School of Medicine, Boston, MA, USA.
authors.forename: D
authors.initials: D
authors.lastname: Felson
authors.affiliation: Department of Medicine, University of California at Davis Medical School, Sacramento, CA, USA.
authors.forename: N E
authors.initials: NE
authors.lastname: Lane
authors.affiliation: Department of Epidemiology and Biostatistics, UCSF, San Francisco, CA, USA. Electronic address: MNevitt@psg.ucsf.edu.
authors.forename: M C
authors.initials: MC
authors.lastname: Nevitt
mesh_terms: D000368:Aged; D000407:Alabama / Q000453:epidemiology; D000975:Antioxidants / Q000032:analysis; D001205:Ascorbic Acid / Q000097:blood*; D016022:Case-Control Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007484:Iowa / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000097:blood* / Q000000981:diagnostic imaging / Q000453:epidemiology; D011859:Radiography; D012016:Reference Values; D012307:Risk Factors; D014810:Vitamin E / Q000097:blood*
chemical_list: D000975:Antioxidants; D014810:Vitamin E; D001205:Ascorbic Acid
keywords: Antioxidants; Knee osteoarthritis; Vitamin C; Vitamin E