Table 1 Study characteristics of the included studies

Benito-Ruiz P 2009

Randomized, double-blind, controlled multicentre trial

Ecuador

Oral

Primary knee osteoarthritis (Kellgren-Lawrence grade I-III)

10 g hydrolyzed collagen for once-daily administration, 111 participants

NA

A matching amount of placebo (lactose) for once-daily administration, 96 participants

59

15/192

VAS (100 scale), WOMAC, SF-36 score

Baseline, 3 months, 5 months

Chen CC 2023

Randomized, double-blind, four-arm, pilot study

Taiwan

Oral

Mild to moderate knee osteoarthritis ( Kellgren–Lawrence grade I to III)

Hydrolyzed collagen type II, 38 participants

Essence of chicken + hydrolyzed collagen type II, 37 participants

6.8 g maltodextrin, 0.007 g xanthan gum, and 0.43 g yeast extract, 38 participants

45–75 years

17/96

VAS pain score, WOMAC score, fat-free mass, grip strength, SF-36

WOMAC score at 8, 16, and 24 weeks; VAS pain score at 7 and 14 days; grip strength, FFM at 24 weeks

JX Jiang 2014

Prospective,single-centre,randomized,doulble-blind,placebo-controlled trial

China

Oral

Knee osteoarthritis (Kellgren- Lawrence score of 0-I to III)

Peptan B 2000 of bovine origin,8 g per day for 6 months, 46 paticipants

NA

Maltodextrin,8 g per day for 6 months,48 participants

40–70

0/94

WOMAC and the Lysholm scoring system

3 months,6 months

Trč T 2011

Prospective, multicentre, randomized, parallel, double-blind study

Czech Republic

Oral

Knee osteoarthritis (functional class I, II, or III)

10 g enzymatic hydrolyzed collagen once daily for 90 consecutive day, 47 participants

NA

1.5 g glucosamine sulfate once daily for 90 consecutive day, 46 participants

40 years or older

NA

VAS (100 scale), WOMAC, SF-36 score, self-assessment, the investigator’s overall opinion, and reduction of the use of rescue medication

− 7, 0, 15, 30, 60, and 90 days