[Reduced pain from osteoarthritis in hip joint or knee joint during treatment with calcium ascorbate. A randomized,...

Although vitamin C is essential for the formation of collagen and proteoglycan and has been shown to minimise surgically induced arthritis in guinea pigs, no controlled trial has examined its effect on human osteoarthritis.

The trial was a multicenter, double-blind, randomised, placebo-controlled, crossover-trial performed by ten general practitioners. The Declaration of Helsinki and the European guidelines for good clinical practice were strictly followed. One hundred and thirty-three patients with radiographically verified symptomatic osteoarthritis of the hip joints and/or the knee joints were treated with one gram of calcium ascorbate or identically looking placebo tablets. The calcium ascorbate tablets and the placebo tablets should be swallowed daily for 14 +/- 3 days respectively, separated by 7 +/- 3 days wash out. The main outcome measure was difference on the 100 mm visual analog scale (VAS) score for pain in a preselected joint. The secondary outcomes were Lequesne score for function and patient preference.

Calculated on an intention-to-treat principle, calcium ascorbate reduced pain significantly compared to placebo (p = 0.0078 by analysis of variance between groups (ANOVA) for difference in VAS, mean difference 4.6 mm (95% CI 1.2-8.0). Similar superiority was found for Lequesne index (p = 0.036, difference 0.56 (95% CI 0.04-1.08) and for patient preference (p = 0.012).

The demonstrated effect is less than half as pronounced as commonly reported for NSAID etc. If the finding can be reproduced with a smaller, acceptable intake of vitamin C this would be of importance considering the large prevalence of osteoarthrosis.