Krill oil improved osteoarthritic knee pain in adults with mild to moderate knee osteoarthritis: a 6-month multicenter, randomized, double-blind, placebo-controlled trial

Stonehouse W, Benassi-Evans B, Bednarz J, Vincent AD, Hall S, Hill CL · The American Journal of Clinical Nutrition

A positive marine-oil trial in knee OA, and the one that has to be read alongside the null ones. The Omega-3 Index rose from 6.0% to 8.9% on krill oil and stayed flat on placebo (p < 0.001). Knee pain improved in both arms, more on krill oil: adjusted between-group difference at 6 months −5.18 on a 0-100 scale (95% CI −10.0 to −0.32, p = 0.04). Stiffness (−6.45, 95% CI −12.1 to −0.9) and physical function (−4.67, 95% CI −9.26 to −0.05) also favoured krill oil. NSAID use, lipids and inflammatory markers did not differ.

Population

Adults 40-65 with clinically diagnosed mild to moderate knee OA, regular knee pain, and habitual long-chain omega-3 intake under 0.5 g/day

Intervention

4 g/day krill oil (0.60 g EPA, 0.28 g DHA, 0.45 g astaxanthin) for 6 months

Comparator

Mixed vegetable oil placebo

Limitations

The between-group difference is 5 points on a 100-point scale, with a confidence interval reaching −0.32 — statistically positive, clinically marginal, and below most definitions of a minimal important difference. Entry criteria required low habitual omega-3 intake, so this is a repletion trial in people who were short of it. Inflammatory markers did not move, which leaves the proposed mechanism unsupported within the trial itself. An erratum was published. Registered NCT03483090.