Green-lipped mussel (Perna canaliculus) extract efficacy in knee osteoarthritis and improvement in gastrointestinal dysfunction: a pilot study

Clinical data demonstrating efficacy for nutraceutical compounds marketed for the symptom relief of osteoarthritis (OA) have been largely contentious. Furthermore, no association has been linked between clinical trial inconsistencies and gastrointestinal (GI) dysfunction. The aim of this study was to primarily investigate the efficacy of a high-dose New Zealand green-lipped mussel (GLM) extract in patients diagnosed with OA of the knee and concurrently assess GLM impact on GI function.

An open label, single group allocation study was conducted, that administered 3,000 mg/day of GLM extract over 8 weeks to 21 subjects diagnosed with knee OA. Outcome measures were scored using the WOMAC, the Lequesne algofunctional index, and the Gastrointestinal Symptom Rating Scale (GSRS) tools. An intention-to-treat analysis was employed and subject data collected at T ₀, T ₄ and T ₈ weeks.

Paired t tests showed significant improvement for the Lequesne, WOMAC (p < 0.001) and GSRS (p = 0.005) scores. A repeated measures ANOVA analysis showed significant improvement in scores for the Lequesne (F = 20.317, p < 0.001), WOMAC (F = 28.383, p < 0.001) and the GSRS (F = 9.221, p = 0.002).

Green-lipped mussel significantly improved knee joint pain, stiffness and mobility. We report for the first time that the administration of GLM extract also significantly improved GI symptoms by 49% in OA patients. Given that GI dysfunction is linked to analgesic medication use, we further conclude that the therapeutic efficacy of the GLM extract used was possibly correlated to its effects on GI function by improving GSRS scores from baseline. Results from this trial highlight the requisite for further clinical investigations of gastrointestinal tract function in OA patients.