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

Joseph GB, McCulloch CE, Nevitt MC, Neumann J, Lynch JA, Lane NE, Link TM · Arthritis Care & Research

The imaging follow-up to Framingham, with smaller associations. Higher vitamin C intake was associated with lower cartilage T2 — the MRI measure of matrix quality — averaged and at the medial tibia, and with lower medial tibial WORMS scores. The standardized coefficients are -0.07 to -0.05, which is a real association and a very small one. Vitamin D, measured in the same subjects, produced coefficients of -0.24 to -0.09, roughly two to three times larger and was the only vitamin whose consistent supplement use predicted less worsening over four years.

Population

Osteoarthritis Initiative participants with Kellgren-Lawrence grades 0-3, followed 4 years

Intervention

Baseline vitamin C and vitamin D intake from diet and supplements by food frequency questionnaire

Comparator

Lower intake, within cohort

Limitations

Observational, and the vitamin C findings are cross-sectional associations with baseline imaging rather than the longitudinal protection the vitamin D arm showed. Effect sizes are near the floor of detectability in a cohort of 1,785. Diet questionnaires misclassify intake. The paper's own conclusion asks for randomized trials of vitamin D and does not make that call for vitamin C. NIH-funded.