Polyphenols are a broad class of naturally occurring compounds found abundantly in fruits, vegetables, tea, coffee, and other plant-based foods. There is a moderate amount of scientific evidence supporting their role in supporting joint health, primarily due to their anti-inflammatory and antioxidant properties. Several studies have shown that certain polyphenols, particularly those found in green tea (such as epigallocatechin gallate, EGCG) and in curcumin (from turmeric), can modulate inflammatory pathways involved in joint diseases like osteoarthritis and rheumatoid arthritis. These compounds may help reduce the production of pro-inflammatory cytokines and suppress oxidative stress, both of which contribute to joint degradation and pain.

However, the evidence is largely based on specific polyphenols rather than the broad category as a whole, and most clinical trials are small, short-term, or use supplements with concentrated extracts rather than polyphenols from whole foods. Despite promising findings, there is a lack of large-scale, long-term randomized controlled trials to firmly establish their efficacy for joint support. Nevertheless, the potential mechanisms are biologically plausible, and polyphenol-rich diets are associated with lower levels of inflammation in epidemiological studies. Thus, while scientific evidence exists and supports their potential benefit, it is not definitive, and the overall evidence for unspecified polyphenols is moderate.