Although several individual FA varied with for RA disease activity status (Fig. 2b, Supplementary Table S2), prednisolone treatment (Fig. 3, Supplementary Table S3) or periodontal status (Fig. 4a, Supplementary Table S4), solely C15:0 was positively associated with CRP (P < 0.01, R = 0.30). This evidence concerns the gene CRP and rheumatoid arthritis.