Erythrocyte levels of the n-6 polyunsaturated fatty acid (PUFA) linoleic acid may be inversely associated with risk for rheumatoid arthritis (RA), according to a recent nested-control study published in the Annals of the Rheumatic Diseases.
Whole blood samples were analyzed from study participants enrolled in the European Prospective Investigation into Cancer and Nutrition study, a European multicenter, prospective cohort study designed to investigate the association between diet and diseases in apparently healthy populations. Participants in whom incident RA developed after enrollment were designated as the “pre-RA” cohort. Total erythrocyte lipid levels were analyzed from the pre-RA cohort (n=96) and from matched controls (n=258). Baseline questionnaires detailed diet, activity, medical history, lifestyle factors, and time to diagnosis.
Among the study participants in the pre-RA group, a significant inverse association existed with erythrocyte membrane n-6 PUFA linoleic acid levels. Furthermore, other PUFA content was correlated with time to diagnosis; with higher levels found the closer an individual was to diagnosis. The trend for linoleic acid increased with time to diagnosis shortening.
The study authors wrote, “We observed that erythrocyte membrane levels of the n-6 PUFA [linoleic acid] were inversely proportional to the risk [for RA] developing, whereas no protective effect was observed with n-3 PUFA.”
They also noted caution about the findings, adding, “Further work is warranted to investigate [whether linoleic acid] is protective against RA development or [whether] lower levels are secondary to metabolic and inflammatory changes occurring before the clinical onset of RA.”
de Pablo P, Romaguera D, Fisk H, et al. High erythrocyte levels of the n-6 polyunsaturated fatty acid linoleic acid are associated with lower risk of subsequent rheumatoid arthritis in a southern European nested case-control study [published February 7, 2018]. Ann Rheum Dis. doi:10.1136/annrheumdis-2017-212274