title: Environmental influences on risk for rheumatoid arthritis.
abstract: OBJECTIVE
  To examine new environmental factors and provide updates on known risk factors for rheumatoid arthritis (RA) in the past 2 years (2006-2008). This review is timely given the expanding information on treatment, pathogenesis and genetic risk factors for RA.
  
  
  RESULTS
  High consumption of red meat does not increase risk of RA, whereas alcohol intake may be protective. The role of vitamin D and oral contraceptives as modifiers of disease risk remains equivocal. Other factors associated with increased risk of RA include higher birthweight, living in the northeastern United States compared with other regions of the country, and lower socioeconomic status. Duration of breastfeeding is inversely associated with RA risk. Several studies have now demonstrated that anti-citrullinated protein antibody positive RA has a specific association with environmental risk factors such as smoking.
  
  
  CONCLUSIONS
  Recent studies have increased our understanding of environmental exposures that modify risk for RA such as smoking and alcohol intake. Other factors such as birthweight, breastfeeding, socioeconomic status and region of birth have also been demonstrated to contribute to risk. ACPA status is associated with specific environmental factors and is therefore important to incorporate into present and future studies.
authors.affiliation: Brigham and Women's Hospital, Boston, Massachusetts 02141, USA.
authors.forename: Katherine P
authors.initials: KP
authors.lastname: Liao
authors.forename: Lars
authors.initials: L
authors.lastname: Alfredsson
authors.forename: Elizabeth W
authors.initials: EW
authors.lastname: Karlson