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7 peer-reviewed studies
What the evidence says
Most UC-II studies are mechanism or observational rather than RCTs that measure a clinical effect — keep findings provisional.
Most evidence is from medium-quality randomised trials published 2009–2025 with a typical study size of 96 participants.
Based on 7 studies · 4 RCTs · 499 total participants
Confidence
ModerateBy outcome
3 studies in the last 5 years
A 180-day multicenter RCT (n=191) found UC-II 40mg/day improved knee-osteoarthritis WOMAC scores versus placebo and versus glucosamine+chondroitin.
Lugo JP et al. · Nutr J (2016)
A multicenter RCT (n=96) found UC-II 40mg improved knee range-of-motion flexibility in healthy subjects with activity-related joint discomfort.
Schon C et al. · J Integr Complement Med (2022)
An RCT in knee osteoarthritis found UC-II reduced WOMAC by 33% vs 14% for glucosamine+chondroitin, with larger VAS and Lequesne improvements.
Crowley DC et al. · Int J Med Sci (2009)
An RCT in healthy subjects with exercise-related joint discomfort found UC-II 40mg improved knee extension and extended pain-free exercise time.
Lugo JP et al. · J Int Soc Sports Nutr (2013)
A 90-day controlled study (n=105, ages 60-80) found adding UC-II to standard osteoarthritis care improved physical quality of life, pain, and function.
Sadigursky D et al. · Acta Ortop Bras (2022)
A review of UC-II in COMPANION ANIMALS (dogs and horses) summarized its oral-tolerance mechanism and cross-species joint benefits.
Gencoglu H et al. · Animals (Basel) (2020)
A 2025 review of UC-II for knee osteoarthritis concluded it is promising but limited by small, often industry-funded trials.
Gupta A et al. · Ann Med (2025)