Of the 10 trials in participants with RA, one reported a benefit (reduced anticollagen IgG levels), and 7 reported no clear benefit compared to a placebo. Two trials found that collagen was inferior to methotrexate, a common medication for RA. All 10 trials were judged to be of poor quality.

Summary of studies: Undenatured collagen for rheumatoid arthritis

Study	Collagen type / Dosage	Duration	Outcome compared to placebo or comparator	Study quality
Farboud et al. 2011	UD / 0.05 mg, 0.5 mg, or 5 mg	24 weeks	Lower collagen IgG antibodies	Poor
Wei et al. 2009	UD / 0.1 mg	24 weeks	Collagen inferior compared to methotrexate	Poor
Zhang et al. 2008	UD / 0.1 mg	24 weeks	Collagen inferior compared to methotrexate	Poor
Thompson et al. 2002	UD / 0.06 mg or 0.54 mg	6 months	–	Poor
Cazzola et al. 2000	UD / 0.25 g	6 months	–	Poor
McKown et al. 1999	UD / 0.5 mg	6 months	–	Poor
Barnett et al. 1998	UD / 0.1 mg, 0.5 mg, or 2.5 mg	24 weeks	–	Poor
Sieper et al. 1996	UD / 1 mg or 10 mg	12 weeks	–	Poor
Barnett et al. 1996	UD / 0.5 mg	12 weeks	–	Poor
Trentham et al. 1993	UD / 10 mg	3 months	–	Poor

Of the 4 trials on people with OA testing undenatured collagen, 3 reported benefits and 1 noted benefits but did not specify whether the effects were statistically significant. Of these trials, 3 were judged to be fair quality and 1 of poor quality.

Summary of studies: Undenatured collagen for osteoarthritis

Study	Collagen type / Dosage	Duration	Outcome(s) compared to placebo	Study quality
Bakilan et al. 2016	UD / 10 mg	3 months	Decreased pain while walking	Fair
Lugo et al. 2016	UD / 40 mg	180 days	Reduced osteoarthritis severity (WOMAC score)	Fair
Stancik et al. 2012	UD / 3 mg or 8 mg	3 months	Greater reduction in osteoarthritis severity (WOMAC score) and pain, statistical significance not reported	Poor
Crowley et al. 2009	UD / 40 mg	90 days	Decreased pain in certain situations compared to glucosamine+chondroitin	Fair

Of the 5 trials on people with OA testing hydrolyzed collagen, 3 reported a benefit, 1 reported no benefit, and 1 reported no effect compared to glucosamine sulfate, a potentially active comparator. Of these, 3 were judged to be of fair quality and 2 of poor quality.

Summary of studies: Hydrolyzed collagen for osteoarthritis

Study	Collagen type / Dosage	Duration	Outcome(s) compared to placebo	Study quality
Kumar et al. 2015	Hydrolyzed / 10 g	13 weeks	Reduced osteoarthritis severity (WOMAC score) and pain	Fair
Schauss et al. 2012	Hydrolyzed / 2 g	70 days	Reduced osteoarthritis severity (WOMAC score), reduced pain, improved physical ability	Fair
Trc et al. 2011	Hydrolyzed / 10 g	90 days	Improved pain and aspects of disease activity compared to glucosamine sulfate	Poor
McAlindon et al. 2011	Hydrolyzed / 10 g	48 weeks	No effect on osteoarthritis severity (WOMAC score)	Fair
Benito-Ruiz et al. 2009	Hydrolyzed / 10 g	6 months	Decreased pain	Poor

Are collagen supplements beneficial for osteoarthritis arthritis or rheumatoid arthritis? Original paper