Causal association of monounsaturated fatty acids with rheumatoid arthritis but not osteoarthritis: A two-sample Mendelian randomization study

•Previous studies on the association of monounsaturated fatty acid intake and arthritis have reported conflicting results.•Genetically predicted monounsaturated fatty acid levels are inversely associated with the risk of rheumatoid arthritis.•We found little evidence suggesting a causal association between monounsaturated fatty acids and osteoarthritis.