Dietary protein, major dietary protein sources, and chronic joint diseases risk

OBJECTIVES: Evidence on dietary protein and chronic joint diseases remains limited. This study aimed to investigate the associations between protein intake and the risk of chronic joint diseases, and to evaluate the mediating roles of inflammation. METHODS: Dietary protein intake was assessed using 24-hour dietary recall. The primary outcomes, including incident OA, RA, gout, and SpA, were ascertained from UK hospital inpatient records. Cox proportional hazards models estimated associations between protein intake and outcomes. Mediation analysis was conducted using the CMAverse R package. RESULTS: During an average follow-up of 12.19-13.18 years, a total of 23,298 incident cases of OA, 2,070 of RA, 2,934 of gout, and 728 of SpA were documented. Higher total protein intake was associated with a reduced risk of gout (Q4 vs. Q1: HR:0.87, 95%CI 0.79-0.97), vegetable protein intake with lower risks of OA (0.89, 0.86-0.93) and RA (0.76, 0.67-0.87), whereas animal protein intake was related to an increased risk of OA (1.07, 1.03-1.12). Regarding protein-rich foods, whole grains, legumes and cheese intake were associated with lower OA risk. Whole grains, seafood, cheese, and yogurt were negatively associated with RA risk. And red meat was associated with increased RA risk. C-reactive protein was identified as a significant mediator for associations of vegetable and animal protein with OA risk, and of vegetable protein with RA risk. CONCLUSION: Higher total protein intake was linked to a lower risk of gout. Vegetable protein intake was associated with reduced risks of OA and RA, whereas animal protein intake was associated with an increased risk of OA.