Bio-optimized Curcuma longa extract is efficient on knee osteoarthritis pain: a double-blind multicenter randomized placebo controlled three-arm study

OBJECTIVES: Comparison of two doses of bio-optimized Curcuma longa extract (BCL) in the management of symptomatic knee osteoarthritis (OA). METHODS: A prospective, randomized, 3-month, double-blind, multicenter, three-group, placebo-controlled trial assessing Patient Global Assessment of Disease Activity (PGADA) and serum sColl2-1, a biomarker of cartilage degradation, as co-primary endpoints. Pain on visual analog scale (VAS), Knee injury and Osteoarthritis Outcome Score (KOOS), and paracetamol/non-steroidal anti-inflammatory drug (NSAID) consumption were used as secondary endpoints. RESULTS: One hundred fifty patients with knee OA were followed for 90 days. Low and high doses of BCL showed a greater decrease of PGADA than placebo. Analysis of sColl2-1 showed in the placebo and BCL low-dose groups, but not in the BCL high-dose group, a transient but non-significant increase of sColl2-1 between T0 and T1. Thereafter, in all groups, sColl2-1 decreased between T1 and T3 (all p < 0.01), but no difference between the groups was found. Pain reduction at day 90 in the low- and high-dose BCL groups (− 29.5 mm and − 36.5 mm) was higher than that in the placebo (− 8 mm; p = 0.018). The global KOOS significantly decreased overtime, but changes were comparable across treatment arms. The ratio of patients with adverse events (AE) related to the product was similar in the placebo and treatment groups, but the number of AE linked to the product was higher in the high-dose BCL group compared to the placebo (p = 0.012). CONCLUSIONS: BCL appeared safe and well-tolerated with no evidence of severe adverse effects. Efficacy analysis suggested positive trends for measurements of PGADA and serum levels of an OA biomarker and showed a rapid and significant decrease of pain in knee OA (Trial registration: ISRCTN, ISRCTN12345678. Registered 21 September 2016—retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT02909621?term=osteoarthritis+curcumin&rank=5—Evaluation of FLEXOFYTOL® Versus PLACEBO (COPRA) NCT02909621). ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s13075-019-1960-5) contains supplementary material, which is available to authorized users.