Fish consumption and myocardial infarction: a second prospective biomarker study from northern Sweden.
BACKGROUND
A beneficial role of fish consumption on the risk of myocardial infarction (MI) has been reported and is mostly ascribed to n-3 (omega-3) fatty acids. However, fish also contains methylmercury, which may increase the risk of MI.


OBJECTIVE
The objective was to determine how fish consumption and erythrocyte concentrations of mercury (Ery-Hg) and selenium (Ery-Se) are related to the risk of MI and whether n-3 fatty acids (eicosapentaenoic and docosahexaenoic acids) in plasma phospholipids (P-EPA+DHA) are protective.


METHODS
This was a case-control study nested within the northern Sweden cohort, in which data and samples were collected prospectively. The study included 431 cases with an MI after data and sample collection, including 81 sudden cardiac deaths (SCDs) and 499 matched controls. Another 69 female cases with controls from a breast cancer screening registry were included in sex-specific analyses.


RESULTS
Odds ratios for the third compared with the first tertile were 0.65 (95% CI: 0.46, 0.91) for Ery-Hg, 0.75 (95% CI: 0.53, 1.06) for Ery-Se, and 0.78 (95% CI: 0.54, 1.11) for P-EPA+DHA. Ery-Hg and P-EPA+DHA were intercorrelated (Spearman's R = 0.34). No association was seen for reported fish consumption. Multivariate modeling did not change these associations significantly. Sex-specific analyses showed no differences in risk associations. High concentrations of Ery-Se were associated with an increased risk of SCD.


CONCLUSIONS
The biomarker results indicate a protective effect of fish consumption. No harmful effect of mercury was indicated in this low-exposed population in whom Ery-Hg and P-EPA+DHA were intercorrelated.
Department of Medicine, Skellefteå Hospital, Skellefteå, Sweden. maria.wennberg@envmed.umu.se
Maria
M
Wennberg
Ingvar A
IA
Bergdahl
Göran
G
Hallmans
Margareta
M
Norberg
Thomas
T
Lundh
Staffan
S
Skerfving
Ulf
U
Strömberg
Bengt
B
Vessby
Jan-Håkan
JH
Jansson
D000328:Adult; D000368:Aged; D000818:Animals; D015415:Biomarkers; D016022:Case-Control Studies; D016757:Death, Sudden, Cardiac / Q000209:etiology; D004032:Diet; D004912:Erythrocytes / Q000737:chemistry; D015525:Fatty Acids, Omega-3 / Q000097:blood; D005260:Female; D005399:Fishes; D006801:Humans; D008297:Male; D008628:Mercury / Q000097:blood; D008875:Middle Aged; D009203:Myocardial Infarction / Q000517:prevention & control*; D011446:Prospective Studies; D012643:Selenium / Q000097:blood; D013548:Sweden
D015415:Biomarkers; D015525:Fatty Acids, Omega-3; D008628:Mercury; D012643:Selenium