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Diet and Risk of Rheumatoid Arthritis in a
Prospective Cohort
MERETE PEDERSEN, CONNIE STRIPP, METTE KLARLUND, SJURDUR F. OLSEN, ANNE M. TJØNNELAND, and MORTEN FRISCH ABSTRACT. Objective. To assess the association between dietary factors and risk of rheumatoid arthritis (RA) in a large prospective cohort. Methods. Information about dietary intake was obtained from a detailed self-administered food frequency questionnaire completed by 57,053 individuals who participated in a prospective cohort. Linking the cohort to the Danish National Patient Registry we identified patients who developed RA. A rheumatologist scrutinized original medical records for these individuals in order to confirm the diagnosis of RA. Cox proportional hazards regression analyses were performed for dietary and lifestyle factors. Results. The average time of followup in the cohort was 5.3 years (range < 1 mo to 7.7 yrs). Sixty-nine individuals were identified with confirmed incident RA. In multivariate models each increase in intake of 30 g fat fish (≥ 8 g fat/100 g fish) per day was associated with 49% reduction in the risk of RA (p = 0.06), whereas medium fat fish (3-7 g fat/100 g fish) was associated with significantly increased risk of RA. Intake of fruit and coffee was not associated with risk of RA. Furthermore, no associations were found between risk of RA and intake of a range of other dietary factors including long chain fatty acids, olive oil, vitamins A, E, C, D, zinc, selenium, iron, and meat. Conclusion. The limited number of patients who developed RA during followup of our large cohort prevented us from concluding that dietary factors are unimportant as risk factors for RA. It appears, however, that if dietary factors are important modifiers of RA risk, they must play a role more than a few years before clinical diagnosis. (J Rheumatol 2005;32:1249-52) Key Indexing Terms: RHEUMATOID ARTHRITIS From the Department of Epidemiology Research, Danish Epidemiology Science Centre, Statens Serum Institut; the Institute of Cancer Epidemiology, Danish Cancer Society; and the Department of Rheumatology, University Hospital of Copenhagen, Copenhagen, Denmark. Supported by grants from The Danish Rheumatism Association, Margarethe Astrid Hedvig Schaufuss Legat, Aase og Ejnar Danielsens Fond, Poul Martin Christiansens Fond, Lily Benthine Lunds Fond, Gangstedfonden, Familien Hede Nielsens Fond, Lægeforeningens Forskningsfond, Apotekerfonden af 1991, Frimodt-Heineke Fonden, Direktør Ib Henriksens Fond, Henny og Helge Holgersens Mindelegat, Dagmar Marshalls Fond, Torben & Alice Frimodts Fond, Krista og Viggo Petersen's Fond, Direktør Kurt Bønnelycke og Hustru fru Grethe Bønnelyckes Fond, Max Fodgaard Fonden, Smedemester Niels Hansen og hustrus legat, and Civilingeniør Frode V. Nyegaard og hustrus Fond. M. Pedersen, MSc, Department of Epidemiology Research, Danish Epidemiology Science Centre, Statens Serum Institut; C. Stripp, Research Dietician, Institute of Cancer Epidemiology, Danish Cancer Society; M. Klarlund, MD, PhD, Department of Rheumatology, University Hospital of Copenhagen; S.F. Olsen, MD, PhD, Department of Epidemiology Research, Danish Epidemiology Science Centre, Statens Serum Institut; A.M. Tjønneland, MD, PhD, Institute of Cancer Epidemiology, Danish Cancer Society; M. Frisch, MD, PhD, Department of Epidemiology Research, Danish Epidemiology Science Centre, Statens Serum Institut. Address reprint requests to M. Pedersen, Department of Epidemiology Research, Statens Serum Institut, Artillerivej 5, DK-2300 København S, Denmark. E-mail: mtb@ssi.dk Accepted for publication February 28, 2005. |