title: Dietary fish and fish oil and the risk of rheumatoid arthritis.
abstract: BACKGROUND
  Intake of fish oil and oily fish has been reported to improve clinical symptoms in people who have rheumatoid arthritis. Whether the intake of oily fish and fish oil might also protect against the development of rheumatoid arthritis is not known.
  
  
  OBJECTIVE
  We investigated the association between intake of oily fish and fish oil supplements and the risk of rheumatoid arthritis in a population-based case-control study.
  
  
  METHODS
  The study comprised 1889 incident cases of rheumatoid arthritis and 2145 randomly selected controls recruited from a geographically defined area of Sweden during 1996-2005. Data on the consumption of oily fish and fish oil supplements 5 years preceding enrollment had been obtained through a questionnaire. We calculated odds ratios (ORs) for the development of rheumatoid arthritis, using logistic regression to adjust for age, residential area, body mass index, smoking, and alcohol consumption.
  
  
  RESULTS
  Compared with subjects who never or seldom consumed oily fish, the OR for developing rheumatoid arthritis was 0.8 (95% confidence interval = 0.6-1.0) for subjects who consumed oily fish 1-7 times a week. The results did not change notably when stratifying the cases for rheumatoid factor or for antibodies to citrullinated peptide antigens. Similar results were seen for subjects consuming oily fish 1-3 times a month. Cases and controls did not differ in their consumption of fish oil supplements.
  
  
  CONCLUSIONS
  Intake of oily fish was associated with a modestly decreased risk of developing rheumatoid arthritis.
authors.affiliation: Division of Cardiovascular Epidemiology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden. magdalena.rosell@ki.se
authors.forename: Magdalena
authors.initials: M
authors.lastname: Rosell
authors.forename: Ann-Marie
authors.initials: AM
authors.lastname: Wesley
authors.forename: Karin
authors.initials: K
authors.lastname: Rydin
authors.forename: Lars
authors.initials: L
authors.lastname: Klareskog
authors.forename: Lars
authors.initials: L
authors.lastname: Alfredsson
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000178:diet therapy / Q000453:epidemiology / Q000517:prevention & control*; D002956:Citrulline / Q000302:isolation & purification; D016001:Confidence Intervals; D005260:Female; D005395:Fish Oils / Q000008:administration & dosage / Q000378:metabolism*; D005396:Fish Products; D006801:Humans; D008297:Male; D008875:Middle Aged; D012217:Rheumatoid Factor / Q000302:isolation & purification; D018570:Risk Assessment; D011795:Surveys and Questionnaires; D013548:Sweden / Q000453:epidemiology; D055815:Young Adult
chemical_list: D005395:Fish Oils; D002956:Citrulline; D012217:Rheumatoid Factor