HEALTH NEWS

Study Title:

Serum Omega-3 Polyunsaturated Fatty Acids and Risk of Incident Type 2 Diabetes in Men

Study Abstract

OBJECTIVE The relationship between fish or omega-3 polyunsaturated fatty acids (PUFAs) and type 2 diabetes is inconclusive. Even contaminants in fish, such as mercury, may modify the effects. We investigated the associations between serum omega-3 PUFAs eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA), docosahexaenoic acid (DHA), α-linolenic acid (ALA), hair mercury, and risk of incident type 2 diabetes in middle-aged and older Finnish men.

RESEARCH DESIGN AND METHODS A total of 2,212 men from the prospective, population-based Kuopio Ischemic Heart Disease Risk Factor study, aged 42-60 years and free of type 2 diabetes at baseline in 1984-1989, were investigated. Serum PUFA and hair mercury were used as biomarkers for exposure. Dietary intakes were assessed with 4-day food recording. Type 2 diabetes was assessed by self-administered questionnaires and fasting and 2-h oral glucose tolerance test blood glucose measurement at re-examination rounds 4, 11, and 20 years after the baseline and by record linkage to hospital discharge registry and reimbursement register on diabetes medication expenses. Cox proportional hazards models were used to analyze associations.

RESULTS During the average follow-up of 19.3 years, 422 men developed type 2 diabetes. Men in the highest versus the lowest serum EPA + DPA + DHA quartile had 33% lower multivariate-adjusted risk for type 2 diabetes (95% CI 13-49; P trend 0.01). No statistically significant associations were observed with serum or dietary ALA, dietary fish or EPA + DHA, or hair mercury.

CONCLUSIONS Serum long-chain omega-3 PUFA concentration, an objective biomarker for fish intake, was associated with long-term lower risk of type 2 diabetes.

From press release:

High concentrations of serum long-chain omega-3 fatty acids may help reduce the risk of type 2 diabetes, according to a University of Eastern Finland study published recently in Diabetes Care. The sources of these fatty acids are fish and fish oils.

Type 2 diabetes is becoming increasingly widespread throughout the world, including Finland. Overweight is the most significant risk factor, which means that diet and other lifestyle factors play important roles in the development of type 2 diabetes. Earlier research has established that weight management, exercise and high serum linoleic acid concentrations, among other things, are associated with reduced risk of diabetes. However, findings on how fish consumption or long-chain omega-3 fatty acids affect the risk of diabetes have been highly contradictory. A protective link has mainly been observed in Asian populations, whereas a similar link has not been observed in European or US studies -- and some studies have even linked a high consumption of fish to increased diabetes risk.

Ongoing at the University of Eastern Finland, the Kuopio Ischaemic Heart Disease Risk Factor Study (KIHD) determined the serum omega-3 fatty acid concentrations of 2,212 men between 42 and 60 years of age at the onset of the study, in 1984-1989.

During a follow-up of 19.3 years, 422 men were diagnosed with type 2 diabetes.

Serum long-chain omega-3 fatty acid concentrations were used to divide the subjects into four categories. The risk of men in the highest serum omega-3 fatty acid concentration quarter to develop type 2 diabetes was 33% lower than the risk of men in the lowest quarter.

The study sheds new light on the association between fish consumption and the risk of type 2 diabetes. A well-balanced diet should include at least two fish meals per week, preferably fatty fish. Fish rich in long-chain omega-3 fatty acids include salmon, rainbow trout, vendace, bream, herring, anchovy, sardine and mackerel, whereas for example saithe and Atlantic cod are not so good alternatives. Weight management, increased exercise and a well-rounded diet built around dietary recommendations constitute the cornerstones of diabetes prevention.

Study Information

Jyrki K. Virtanen, Jaakko Mursu, Sari Voutilainen, Matti Uusitupa, Tomi-Pekka Tuomainen.
Serum Omega-3 Polyunsaturated Fatty Acids and Risk of Incident Type 2 Diabetes in Men: The Kuopio Ischaemic Heart Disease Risk Factor Study
Diabetes Care
2014 January
University of Eastern Finland