title: Impact of the environment on multiple sclerosis.
abstract: BACKGROUND
  Epidemiological studies suggest that environmental factors play a significant role in the development of multiple sclerosis. This article presents current knowledge on the impact of the environment on disease risk and disease course.
  
  
  METHODS
  We have conducted searches in PubMed for «multiple sclerosis» combined with «environment» as well as relevant environmental factors.
  
  
  RESULTS
  It is highly likely that an interaction between genetic and environmental factors determines who will develop multiple sclerosis. Epstein-Barr virus infection, smoking, and low vitamin D levels are the environmental factors that have shown the strongest and most consistent association with development of the disease. Low vitamin D levels are also associated with high disease activity. Other risk factors include obesity and high salt intake.
  
  
  CONCLUSIONS
  Although epidemiological studies have identified a number of environmental factors with potential aetiological relevance, and the importance of these is supported by experimental studies, there is still insufficient evidence to establish a causal role for these factors in multiple sclerosis.
authors.affiliation: Nevrologisk avdeling Sykehuset Innlandet Lillehammer.
authors.forename: Kristin Ingeleiv
authors.initials: KI
authors.lastname: Løken-Amsrud
authors.affiliation: Avdeling for immunologi og transfusjonsmedisin Oslo universitetssykehus, Rikshospitalet.
authors.forename: Andreas
authors.initials: A
authors.lastname: Lossius
authors.affiliation: Nevrologisk avdeling Haukeland universitetssykehus og KG Jebsen senter for MS-forskning Klinisk institutt 1 Universitetet i Bergen.
authors.forename: Øivind
authors.initials: Ø
authors.lastname: Torkildsen
authors.affiliation: Nevroklinikken Akershus universitetssykehus og Institutt for klinisk medisin Universitetet i Oslo.
authors.forename: Trygve
authors.initials: T
authors.lastname: Holmøy
mesh_terms: D004781:Environmental Exposure / Q000009:adverse effects*; D020031:Epstein-Barr Virus Infections / Q000150:complications / Q000503:physiopathology; D006801:Humans; D008214:Lymphocytes / Q000502:physiology; D009103:Multiple Sclerosis / Q000209:etiology* / Q000503:physiopathology; D009765:Obesity / Q000150:complications; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects / Q000503:physiopathology; D017673:Sodium Chloride, Dietary / Q000009:adverse effects / Q000378:metabolism; D014808:Vitamin D Deficiency / Q000150:complications / Q000503:physiopathology
chemical_list: D017673:Sodium Chloride, Dietary