Associations Between Vitamins C and D Intake and Cartilage Composition and Knee Joint Morphology Over 4 Years: Data From the Osteoarthritis Initiative

Objective To determine the cross-sectional and longitudinal associations of vitamin C and D intake with magnetic resonance imaging (MRI) measures of cartilage composition (T2) and joint structure (cartilage, meniscus, and bone marrow) using data from the Osteoarthritis Initiative (OAI) cohort. Methods A total of 1,785 subjects with radiographic Kellgren/Lawrence knee grades 0-3 in the right knee were selected from theOAIdatabase. Vitamins C and vitamin D intake (diet, supplements, and total) were assessed using the Block Brief 2000 Food Frequency Questionnaire at baseline. TheMRIanalysis protocol included 3T cartilage T2 quantification and semiquantitative joint morphology gradings (Whole-Organ Magnetic Resonance Imaging Score [WORMS]) at baseline and 4 years. Linear regression was used to assess the association between standardized baseline vitamin intake and both baselineWORMSscores and standardized cartilage T2 values. Results Higher vitamin C intake was associated with lower average cartilage T2 values, medial tibia T2 values, and medial tibiaWORMSscores (standardized coefficient range -0.07 to -0.05,P< 0.05). Higher vitamin D intake was associated with a lower cartilageWORMSsum score and medial femurWORMSscore (standardized coefficient range -0.24 to -0.09,P< 0.05). Consistent use of vitamin D supplements of 400IUat least once a week over 4 years was associated with significantly less worsening of cartilage, meniscus, and bone marrow abnormalities (odds ratio range 0.40-0.56,P< 0.05). Conclusion Supplementation with vitamin D over 4 years was associated with significantly less progression of knee joint abnormalities. Given the observational nature of this study, future longitudinal randomized controlled trials of vitamin D supplementation are warranted.