Effect of Diet and Dietary Supplements on Gout-Related Outcomes: A Systematic Review of Randomised Controlled Trials.

Objective: Gout is an inflammatory arthritis caused by elevated serum uric acid (SUA) concentrations, leading to monosodium urate crystal deposition in the joints and clinical symptoms. Various dietary supplements and dietary patterns have been explored as potential strategies to reduce SUA concentrations and alleviate gout manifestations. Methods: A systematic review was conducted across three major databases (PubMed, EBSCO, and clinicaltrials.gov), to identify randomised controlled trials evaluating the effects of dietary supplements and dietary patterns on gout-related outcomes. Although a meta-analysis was not performed, 27 studies met the inclusion criteria and were synthesised narratively. Results: Most studies investigated outcomes such as SUA concentrations, frequency of gout flares, joint pain, swelling, tenderness, renal function, cardiometabolic parameters, anthropometric measures, and quality of life. The assessed supplements included cherry juice or extract, n-3 fatty acids, vitamin C, and various traditional Chinese medicine (TCM) formulations, such as Rebixiao granules, compound Tufuling oral liquid, compound Qingbi granules, Yellow-Dragon Wonderful-Seed, modified Simiao Tang, Chuanhu, Weicao, and the Simiao Pill. The findings were mixed and often contradictory, with some studies reporting improvements in SUA levels and gout flare frequency, while others suggesting no effect. Additionally, many studies reported a range of adverse events. Conclusion: Current evidence on the effectiveness of dietary supplements and dietary patterns in managing gout is inconclusive, with only modest benefits observed in selected interventions. High-quality, well-designed randomised controlled trials are required to establish clear dietary recommendations for the management of gout.