Proline is a non-essential amino acid that plays a fundamental role in the synthesis of collagen, a primary structural protein in cartilage and other connective tissues. The rationale for using proline to support or treat cartilage damage is rooted in its biological function: proline is a major constituent of collagen, and adequate collagen production is necessary for the maintenance and repair of cartilage. Scientific studies have shown that collagen supplements, which are rich in proline and other amino acids, may support joint health and reduce symptoms of osteoarthritis. However, specific clinical studies examining the direct effect of isolated proline supplementation on cartilage repair or regeneration in humans are limited.

Most of the evidence supporting proline's role comes from basic science and animal studies, which demonstrate that proline is essential for collagen formation. Some in vitro (cell culture) research also supports its involvement in chondrocyte (cartilage cell) function. Nevertheless, there is a lack of robust, high-quality clinical trials directly examining proline supplementation for cartilage damage in humans. Therefore, while the use of proline is scientifically plausible and supported by fundamental biochemistry, the direct clinical evidence for its efficacy in treating cartilage damage is weak. It is more commonly used as part of broader collagen or protein supplementation strategies rather than as a standalone treatment.