A Meta-Analysis of the Impact of Nutritional Supplementation on Osteoarthritis Symptoms

Mathieu S, Soubrier M, Peirs C, Monfoulet LE, Boirie Y, Tournadre A · Nutrients

Puts the supplements side by side. Curcumin (12 studies, 724 versus 714 controls) improved pain and function against placebo but not against an active treatment — NSAIDs, chondroitin or paracetamol. Ginger (3 studies, 166 versus 164) improved pain and nothing else, and that result rests on one trial: dropping it takes the effect from a standardized mean difference of −3.76 to −0.20 (95% CI −0.44 to 0.04). Vitamin D (3 studies) improved pain and function, small in size, with no change in total WOMAC or stiffness. Omega-3 (2 studies) improved WOMAC function but not pain. Vitamin E (5 studies) changed nothing. Split by trial quality, the herbal formulations' function benefit is there only in the weaker studies (SMD −2.04 below a Jadad score of 3, −0.08 at 4 or above), while curcumin's holds in the stronger ones and disappears in the weaker.

Population

52 references, 50 of them in knee osteoarthritis, across curcumin, ginger, vitamin D, omega-3 and vitamin E

Intervention

Nutritional supplementation

Comparator

Placebo or active treatment

Limitations

Pools heterogeneous preparations under nutrient headings, and the curcumin finding — significant against placebo, not against active comparators — is the pattern that most needs a bias explanation and does not get one. Several arms are thin: two trials for omega-3, three each for ginger and vitamin D, with the ginger dose reported in only one of the three. Egger's test flags the ginger inflammation-marker analysis (p = 0.01) and the subgroup analysis by control type or study quality was impossible for ginger, vitamin D, omega-3 and multivitamin. No external funding; registered PROSPERO CRD42021253457.