Evidence Level
Chondroitin sulfate has a robust evidence base for knee osteoarthritis. The landmark Kahan et al. (2009) trial demonstrated both symptomatic and structural benefits over 2 years with pharmaceutical-grade CS. The CONCEPT trial (Reginster et al., 2017) established non-inferiority to celecoxib, a prescription NSAID, for pain relief. However, results have been inconsistent across trials, largely due to variation in product quality — pharmaceutical-grade CS from regulated European manufacturers consistently outperforms unregulated over-the-counter products. A 2018 ESCEO guideline recommends pharmaceutical-grade chondroitin sulfate as a first-line treatment for knee OA. The GAIT trial confirmed additive benefit when combined with glucosamine in the moderate-to-severe subgroup.