The effects of bromelain on osteoarthritis symptoms: A systematic review

Background and aims: Osteoarthritis (OA) is the most common skeletal and excruciating disease worldwide. This study aimed to investigate bromelain’s effect and underlying mechanism on OA symptoms. Methods: This systematic review was designed according to the PRISMA guidelines. An extensive search was undertaken in various databases, including PubMed, Web of Science, EMBASE, and Scopus. Finally, ۱۴ articles were retrieved considering the inclusion and exclusion criteria of the study. The desired data were extracted and entered into an Excel file, and the outcomes of the studies underwent investigation. Results: Bromelain downregulates inflammatory cytokines such as tumor necrosis factor (TNF)-α, interleukin ۶ (IL-۶), IL-۸, IL-۱β, and interferon γ expression in synovial fibroblasts. In addition, bromelain inserts analgesic effects by decreasing vascular permeability to bradykinin and inhabitation its generation. Bromelain counteracts by increasing the levels of TNF-α, IL-۱β, inducible nitric oxide synthase (iONS) levels, and lipid peroxidation while reducing those of superoxide dismutase, catalase, and prolidase. Another main antinociceptive effect property of bromelain is associated with its anti-inflammatory effect by relieving neuroinflammation and synovial membrane inflammation. Conclusion: Bromelain indicated good therapeutic effects on reducing OA symptoms due to its anti-inflammatory and antioxidant effects. Although no specific bromelain-related side effects were not reported in the included studies, it is recommended that more laboratory studies should be conducted with different doses and appropriate methodology.