The efficacy and safety of curcumin for knee osteoarthritis Original paper

In this network meta-analysis of randomized controlled trials in participants with knee osteoarthritis, curcumin was effective for reducing pain, but not for improving function.

The effect of curcumin supplementation on participants with diagnosed knee osteoarthritis (OA; most often diagnosed with the American College of Rheumatology criteria or radiological criteria).

The outcomes examined were Visual Analog Scale (VAS) pain score, total Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score (and subscores for pain, physical function, and stiffness), the use of a rescue medication (i.e., the use of a stronger medication to provide relief from severe pain or disability), and adverse events.

A total of 2,175 participants with knee OA.

This network meta-analysis of 23 randomized controlled trials examined the efficacy and safety of 6 types of interventions, including curcumin, chondroprotective (CP) supplements (e.g., glucosamine, chondroitin), curcumin + CP drugs, curcumin + nonsteroidal anti-inflammatory drugs (NSAIDs), NSAIDs alone, and a placebo. The intervention medications were taken for 4 to 12 weeks. The dose of curcumin ranged from 80 mg per day (nanocurcumin) to 2,000 mg per day.

The studies were conducted in India (12 studies), Iran (3 studies), 2 studies each in Australia and Thailand, and 1 study each in Armenia, Belgium, Japan, and Iraq.

Compared with a placebo, curcumin alone reduced VAS pain scores (9 studies), total WOMAC scores (9 studies), and WOMAC pain scores (8 studies).

Compared with a placebo, curcumin + NSAIDs, curcumin alone, and NSAIDs alone reduced the risk of using a rescue medication. Furthermore, curcumin + NSAIDs was more likely than the other interventions to reduce the risk of using rescue medications (11 studies).

Compared with a placebo, curcumin + NSAIDs and curcumin alone reduced the risk of adverse events. Furthermore, curcumin + NSAIDs was more likely than the other interventions to reduce the risk of adverse events (20 studies).*

Compared with placebo, no interventions were effective for improving WOMAC physical function (7 studies) or stiffness scores (7 studies).

A limitation of this study is that the production processes and purity of the curcumin products examined varied widely.

The funnel plots for VAS pain score and total WOMAC score were poor, showing that there may be publication bias in the findings related to these two outcomes.

*Although this study suggested that curcumin + NSAIDs had the lowest risk of adverse events, there might be an interaction between curcumin and NSAIDs. Curcumin may have an antiplatelet effect, which would increase the risk of bleeding that is present with NSAIDs.^[1] However, the evidence is weak.