title: Serum long-chain n-3 polyunsaturated fatty acids, mercury, and risk of sudden cardiac death in men: a prospective population-based study.
abstract: OBJECTIVE
  Fish consumption has been associated with reduced risk of cardiovascular diseases (CVD), especially sudden cardiac death (SCD). Fish is the major source of long-chain n-3 polyunsaturated fatty acids (PUFA) eicosapentaenoic acid and docosahexaenoic acid. It is also a major source of methylmercury, which was associated with increased risk of CVD in this study population. Impact of interaction between long-chain n-3 PUFA and methylmercury on the SCD risk is unknown.
  
  
  METHODS
  A total of 1857 men from the prospective, population-based Kuopio Ischaemic Heart Disease Risk Factor study, aged 42-60 years and free of CVD at baseline in 1984-1989, were studied. Serum long-chain n-3 PUFA was used as the marker for long-chain n-3 PUFA intake and hair mercury as the marker for mercury exposure.
  
  
  RESULTS
  During the mean follow-up of 20.1 years, 91 SCD events occurred. In the multivariate Cox proportional hazards regression models, serum long-chain n-3 PUFA concentration was not associated with the risk of SCD until hair mercury was accounted for; then the hazard ratio (HR) in the highest vs. lowest tertile was 0.54 [95% confidence interval (CI) 0.32 to 0.91, p for trend = 0.046]. When the analyses were stratified by hair mercury content, among those with lower hair mercury, each 0.5 percentage unit increase in the serum long-chain n-3 PUFA was associated with HR of 0.77 (95% CI 0.64 to 0.93), whereas no association was seen among those with higher hair mercury (p for interaction = 0.01). Among the individual long-chain n-3 PUFA, docosahexaenoic acid was most strongly associated with the risk.
  
  
  CONCLUSIONS
  High exposure to mercury may reduce the benefits of long-chain n-3 PUFA on SCD.
authors: University of Eastern Finland, Institute of Public Health and Clinical Nutrition, Kuopio, Finland. jyrki.virtanen@uef.fi
authors: Jyrki K
authors: JK
authors: Virtanen
authors: Jari A
authors: JA
authors: Laukkanen
authors: Jaakko
authors: J
authors: Mursu
authors: Sari
authors: S
authors: Voutilainen
authors: Tomi-Pekka
authors: TP
authors: Tuomainen
mesh_terms: D000328:Adult; D016757:Death, Sudden, Cardiac; D004281:Docosahexaenoic Acids / Q000097:blood; D015118:Eicosapentaenoic Acid / Q000097:blood; D005231:Fatty Acids, Unsaturated / Q000097:blood*; D006197:Hair / Q000378:metabolism; D006801:Humans; D008297:Male; D008628:Mercury / Q000633:toxicity*; D008875:Middle Aged; D015233:Models, Statistical; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012306:Risk
chemical_list: D005231:Fatty Acids, Unsaturated; D004281:Docosahexaenoic Acids; D015118:Eicosapentaenoic Acid; D008628:Mercury