Effect of collagen supplementation on knee osteoarthritis: an updated systematic review and meta-analysis of randomised controlled trials

OBJECTIVES: To perform a systematic review and meta-analysis to assess the clinical efficacy of collagen-based supplements on knee osteoarthritis (OA) symptoms. METHODS: Until October 2023, we conducted searches on the MEDLINE, EMBASE, Web of Science, and Scopus databases to identify randomised controlled trials (RCTs) that reported the effects of oral collagen-based supplements on knee OA. Quantitative data from outcomes were pooled using a random- or fixed-effects model (depending on inter-study variability) and the generic inverse variance method. The Cochrane Risk of Bias 2.0 tool was employed to assess the risk of bias. RESULTS: This systematic review incorporated information of 870 participants included from 11 RCTs, with 451 allocated to the collagen supplementation group and 419 to the placebo group. The meta-analysis revealed an overall significant improvement of both function [MD, -6.46 (95% CI -9.52, -3.40); I2=75%; p=0.00001] and pain scores [MD, -13.63 (95% CI -20.67, -6.58); I2=88%; p=0.00001], favouring collagen supplementation. CONCLUSIONS: The results of this meta-analysis suggest that oral collagen administration relieves OA symptoms. Our findings revealed noteworthy improvements, statistically and clinically, in both functional and pain scores.