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. 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 mg 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. Funded by Swisse Wellness, whose krill oil was tested and which designed the trial with the investigators and monitored it, with no role in analysis or reporting. Registered NCT03483090.