15 Jan Risk of Diabetes and Fish Intake
MedicalResearch.com: What are the main findings of the study?
Dr. Virtanen: The main finding was that serum long-chain omega-3 polyunsaturated fatty acid (PUFA) concentration, an objective biomarker of fish and long-chain omega-3 PUFA intake, was associated with a lower risk of incident type 2 diabetes during the average follow-up of 19.3 years in middle-aged and older men from Eastern Finland. The risk was 33% lower in the highest vs. the lowest quartile after adjustment for potential confounders. In contrast, hair mercury, a marker for long-term exposure to mercury, was not associated with the risk. Previously in this study population, high hair mercury content has been associated with higher risk of cardiovascular diseases and attenuation of the beneficial impact of long-chain omega-3 PUFA on the risk. Also, we did not find associations with the intermediate-chain length omega-3 PUFA alpha-linolenic acid, either, which is a plant-based omega-3 PUFA. This suggests that the findings were specific to the long-chain omega-3 PUFAs from fish.
MedicalResearch.com: Were any of the findings unexpected?
Dr. Virtanen: It was slightly unexpected that the long-chain omega-3 PUFA concentration did associate with the risk. In the previous studies a beneficial effect has been found mainly in the studies in Asian populations and no association or even an increased risk with higher fish consumption has been found in studies in Europe and the USA. One of the reasons that we were able to find an association may be that we had very detailed information about type 2 diabetes incidence in this study population, so we were able to catch those who got the diagnosis during the follow-up.
MedicalResearch.com: What should clinicians and patients take away from your report?
Dr. Virtanen: As with the recommendations for cardiovascular disease prevention, it may be beneficial to have a few fish meals per week, preferably with fatty fish, in order to reduce also the risk of type 2 diabetes.
MedicalResearch.com: What recommendations do you have for future research as a result of this study?
Dr. Virtanen: In the previous studies no association has been found in the studies from Europe, whereas in the studies from Asia/Australia fish or long-chain omega-3 PUFA intakes were associated with lower risk of type 2 diabetes and in the studies from the USA with higher risk. However, in the US studies where an objective biomarker was used, circulating long-chain omega-3 PUFA concentrations were not found to be associated with higher risk. This suggests that the increased risk observed with dietary intakes may be related to the dietary assessment method. Because of these issues, there is a need for further research from diverse study populations and with objective biomarkers of exposure in order to clarify the role of the omega-3 PUFAs on the prevention of type 2 diabetes.
Serum Omega-3 Polyunsaturated Fatty Acids and Risk of Incident Type 2 Diabetes in Men: The Kuopio Ischaemic Heart Disease Risk Factor Study
Virtanen JK, Mursu J, Voutilainen S, Uusitupa M, Tuomainen TP.
Diabetes Care. 2014 Jan;37(1):189-96. doi: 10.2337/dc13-1504. Epub 2013 Sep 11.