British Journal of Nutrition

Research Article

Markers of high fish intake are associated with decreased risk of a first myocardial infarction

C. G. Hallgrena1a4, G. Hallmansa5, J.-H. Janssona7 c1, S. L. Marklunda6, F. Huhtasaaria8, A. Schütza2, U. Strömberga2, B. Vessbya3 and S. Skerfvinga2

a1 Unit for Community Medicine, County Council of Västerbotten, 901 85 Umeå, Sweden

a2 Department of Occupational and Environmental Medicine, University Hospital, SE-221 85 Lund, Sweden

a3 Department of Public Health and Caring Sciences, Uppsala University, 751 25 Uppsala, Sweden

a4 Department of Family Medicine, Umea University, 901 85 Umea, Sweden

a5 Department of Public Health and Clinical Medicine, Nutritional Research ,Umea University, 901 85 Umea, Sweden

a6 Department of Medical Biosciences, Clinical Chemistry, Umea University, 901 85 Umea, Sweden

a7 Department of Medicine, Skelleftea Hospital, 931 86 Skellef, Sweden

a8 Department of Medicine, Sunderby Hospital, 971 80 Lulea, Sweden

Abstract

High intake of fish has been associated with reduced risk of CHD. The high content of n-3 polyunsaturated fatty acids (PUFA) in fish has been suggested to be a protective factor. In addition, fish is the entirely dominating source of methylmercury for the general population, and the concentration of Hg in erythrocytes (Ery-Hg) is often used as an index of fish consumption. Our aim was to study the relationships between a first-ever myocardial infarction, Ery-Hg, activity of gluthathione peroxidase in erythrocytes (Ery-GSH-Px) and plasma concentration of the n-3 PUFA eicosapentaenoic and docosahexaenoic acids (P-PUFA). In a population-based prospective nested case–control study within Northern Sweden seventy-eight cases of a first-ever myocardial infarction were compared with 156 controls with respect to Ery-Hg, P-PUFA and Ery-GSH-Px. Both Ery-Hg and P-PUFA, but not Ery-GSH-Px, were significantly (P<0·0001) higher in subjects reporting high fish intake (at least one meal per week) than in those with lower intake. This finding suggests that Ery-Hg and P-PUFA reflect previous long-term fish intake. Low risk of myocardial infarction was associated with high Ery-Hg or high P-PUFA. In a multivariate model the risk of myocardial infarction was further reduced in subjects with both high Ery-Hg and high P-PUFA (odds ratio 0·16, 95 % CI 0·04, 0·65). In conclusion, there is a strong inverse association between the risk of a first myocardial infarction and the biomarkers of fish intake, Ery-Hg and P-PUFA, and this association is independent of traditional risk factors.

(Received November 17 2000)

(Revised April 12 2001)

(Accepted May 06 2001)

Correspondence:

c1 *Corresponding author: Dr J.-H. Jansson, fax +46 910 771 157, email janhakan.jansson.ss@vll.se

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