title: The effects of vitamin C supplementation on incident and progressive knee osteoarthritis: a longitudinal study.
abstract: OBJECTIVE
  To evaluate the association between vitamin C supplementation and the incidence and progression of radiographic knee osteoarthritis (OA).
  
  
  METHODS
  Prospective cohort study.
  
  
  METHODS
  Clearwater Osteoarthritis Study (COS): (1988 to the present) a longitudinal study.
  
  
  METHODS
  Male and female COS participants aged 40 years and above (n 1023). The study exposure was the participants' self-reported history of vitamin C supplementation. The participants underwent biennial, sequential knee radiographs, which were assessed using the Kellgren-Lawrence ordinal scale to determine evidence of the study 2 outcomes: incident radiographic knee OA (RKOA) and progression of RKOA.
  
  
  RESULTS
  Individuals without baseline knee OA who self-reported vitamin C supplement usage were 11% less likely to develop knee OA than were those individuals who self-reported no vitamin C supplement usage (risk ratio (RR)=0.89, 95% CI 0.85, 0.93). Among those participants with RKOA at baseline, vitamin C supplement usage did not demonstrate an association with RKOA progression (RR=0.94, 95% CI 0.79, 1.22).
  
  
  CONCLUSIONS
  In the present prospective cohort study, we found no evidence to support a protective role of vitamin C in the progression of knee OA. However, after controlling for confounding variables, these data suggest that vitamin C supplementation may indeed be beneficial in preventing incident knee OA. Given the massive public health burden of OA, the use of a simple, widely available and inexpensive supplement to potentially reduce the impact of this disease merits further consideration.
authors: Department of Epidemiology, College of Public Health, University of South Florida, Clearwater, FL 33755, USA.
authors: Jennifer
authors: J
authors: Peregoy
authors: Frances Vaughn
authors: FV
authors: Wilder
mesh_terms: D000328:Adult; D000368:Aged; D000975:Antioxidants / Q000008:administration & dosage*; D001205:Ascorbic Acid / Q000008:administration & dosage*; D015331:Cohort Studies; D019587:Dietary Supplements / Q000706:statistics & numerical data*; D018450:Disease Progression; D005260:Female; D006801:Humans; D015994:Incidence; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging / Q000453:epidemiology* / Q000517:prevention & control*; D011446:Prospective Studies; D011859:Radiography; D012650:Self Disclosure
chemical_list: D000975:Antioxidants; D001205:Ascorbic Acid