People with high content of omega-3 fatty acids in blood have lower risk of venous thrombosis

Blood clots formed in the veins of the leg and lungs, collectively named venous thromboembolism (VTE), is a common disease with severe complications. The occurrence of VTE has increased during the last decades, and it is important to find out whether lifestyle factors can lower the risk of VTE. We therefore investigated whether a high content of  omega-3 fatty acids in blood was related to risk of VTE in the general population. We found that persons with high content of omega-3 fatty acids in blood had a 28% lower risk of VTE. Our findings were recently published in the American Journal of Clinical Nutrition and highlighted by an editorial commentary in the same journal.

Omega-3 fatty acids are essential fatty acids, meaning that they cannot be synthesized in the body and that the content in blood reflect the dietary intake of seafood or omega-3 enriched supplements (e.g. cod liver oil). Fatty fish, such as salmon, trout, and mackerel, has a high content of omega-3 fatty acids, while lean fish, such as cod, has a low content of omega-3 fatty acids. Studies have shown that omega-3 fatty acids can have beneficial effects on key mechanisms involved in blood clot formation.

Previous studies on the relationship between omega-3 fatty acids and VTE have estimated dietary omega-3 intake based on self-reported intake of fat fish and supplements. Since this estimation is not completely accurate, the true effect of omega-3 can be underestimated in such studies. Consequently, these studies have reported mixed results on the link between omega-3 fatty acid intake and VTE risk. In our recent study, we have for the first time studied whether omega-3 levels measured directly in blood were linked to VTE risk.

In our study of omega-3s and risk of venous thromboembolism, about 17,000 persons living in Nord-Trøndelag County in Norway participated. They went to a health examination and donated blood samples in 2006-08. The amount of omega-3 fatty acids in blood samples from each participant was measured, and all VTE events among the participants were registered until 2020. During 12-years of median follow-up, 340 participants experienced a VTE event. We found that those with high omega-3 levels (upper tertile) in blood had 28% lower risk of venous thromboembolism compared to those with low levels (lower tertile).

Our findings suggest that a high dietary intake of omega-3 fatty acids derived from seafood is associated with lowered risk of future VTE. However, our original findings needs to be validated in other populations and ultimately tested in randomized clinical trials.

The first author of this study, Magdalena Johansson, is a haematologist and researcher from Umeå University, Sweden. She collaborated with TREC on this study when she was a visiting researcher in Tromsø during spring 2024.

Reference:

Johansson M, Brækkan SK, Giskeødegård GF, Wade KH, Hindberg KD, Timpson N, Davey Smith G, Hveem K, Åsvold BO, Brumpton BM, Hansen JB. High concentrations of polyunsaturated n-3 fatty acids in serum are inversely associated with risk of future incident venous thromboembolism – the HUNT cohort study. Am J Clin Nutr. 2025 Nov;122(5):1195-1203.

How Blood Type Influences Risk of Venous Thrombosis

Formation of blood clots in the veins of the legs and lungs, also known as venous thromboembolism (VTE), is a common disease with severe complications including death. The ABO blood group system, which determines whether a person has blood type A, B, AB, or O, is not only important for blood transfusions but also plays a major role for VTE risk. Individuals with non-O blood types (A, B, or AB) have higher risk of venous thromboembolism (VTE) and 20-30% of the VTE events in the population are attributed to non-O blood types. While the association between ABO blood type and venous thrombosis is well-known, the biological mechanisms behind this association are not completely understood.

A recent study from the Thrombosis Research Group (TREC) at UiT - The Arctic University of Norway and University Hospital of North Norway, in collaboration with researchers from NTNU (Trondheim) and international researchers from France and USA, took a step toward unravelling these mechanisms. Using high-quality data from the Trøndelag Health Study (HUNT), we combined advanced protein measurements (proteomics) and genetic analyses (genomics) to investigate how the ABO blood group system influences VTE risk.

The study focused on a protein called histo–blood group ABO system transferase (BGAT), which is produced by the ABO gene. BGAT is a combined term for the enzymes that determines ABO blood type. These enzymes add the blood type antigens (A- and B-antigen) to red blood cells but also adds these antigens to other cells and proteins in the body. We found that plasma BGAT levels were strictly genetically regulated and that elevated BGAT levels were associated with an increased risk of VTE. The association between BGAT levels and VTE risk remained even after accounting for clotting-related factors in the blood which are already known to be affected by blood type.

Our research highlights the power of international collaboration and how the use of new technologies in unique population studies can explore how blood type affects disease risk. While this study provides new insights, it is just the first step in a broader effort to understand the complex relationship between the ABO system and VTE risk. Future research will build on these findings and methods to uncover hitherto unknown pathways through which blood type influences VTE risk, paving the way for improved prevention and treatment strategies for VTE.

The paper was recently published and was highlighted with a commentary in the world-leading journal in hematology Blood.

Reference: Onsaker AL, Arntzen AY, Trégouët DA, Nøst TH, Tang W, Guan W, Jonasson C, Morange PE, Hindberg KD, Folsom AR, Hveem K, Morelli VM, Hansen JB. Histo-blood group ABO system transferase plasma levels and risk of future venous thromboembolism: The HUNT Study. Blood. 2025

Evaluation of TREC by the Research Council of Norway

Evaluation of the Thrombosis Research group (TREC) by international experts commissioned by the Research Council of Norway (EvalMedHelse)

EvalMedHelse, or the Evaluation of Medical and Health Research in Norway, is a nationwide initiative designed to assess the quality, relevance, and societal impact of medical and health research conducted across Norwegian institutions during the years 2012-2022. Commissioned by the Research Council of Norway (RCN), international experts evaluated research institutions, departments and research groups with regards to organization, scientific and public dissemination, and contributions to their specific research fields. The evaluation was based on self-reports and available public information about the institutions, departments and research groups.

Recently, TREC, a translational research group focusing on the etiology of venous thromboembolism, received the evaluation report from EvalMedHelse 2023-2024. Overall, the research group got a high score, with marks of 4 or 5 on all items (5 is highest). The report highlighted that TREC is a successful and focused translational research group, that TREC during 25 years of research has gained a high international reputation, operating at a very high standard and achieved the position of international opinion leader with a large network of national and international collaborators.

TREC was evaluated as a very well-organized research group with strong leadership. The report further stated that “The research quality in relation to both contribution and leadership in research and outputs are excellent in the specific field of VTE”. “TREC has contributed to the reputation of the institution by substantial international visibility due to publications in high-ranked international peer-reviewed journals as well as many invited and selected oral presentations at important international conferences in the field (e.g., ISTH)”. With regards to societal impact, “TREC has contributed to increase academic competence of medical doctors at hospitals in Norway” and “taken a great focus on dissemination of project results and on increasing the public awareness and knowledge of VTE in the society”.

As a comment to the evaluation report, professor Hansen, the research group leader of TREC, states that “TREC is satisfied by the findings in the evaluation report, and we are encouraged to continue working to improve the organization as well as the scientific and societal relevance and impact of TREC. As the evaluation has been resource-demanding, and a huge effort for everyone involved, it will be exciting to see how the recommendations in the evaluation report will be implemented in the strategies and organization at the institutional- and department levels with goal to improve the framework for research in general and top research in particular”.

You can read the full report here: EvalMedHelse Report TREC

John Bjarne Hansen  –  Professor

Sigrid Kufaas Brækkan  –  Professor

Omri Snir  –  Associate Professor

Thor Ueland  –  Professor II

Kristian Dalsbø Hindberg  –  Researcher

Vania Maris Morelli  –  Researcher

Nadezhda Latysheva  –  Research technician

Samantha Xavier  –  Doctoral Research Fellow

Christabel Esi Damoah  –  Doctoral Research Fellow

Eduarda Mazagao Guerreiro  –  Researcher

Maryam Hosseini  –  Doctoral Research Fellow

Christopher Antoun  –  Doctoral Research Fellow

Lisa Jakobsen  –  Doctoral Research Fellow

Celina Janene Cathro  –  Doctoral Research Fellow

Ellen-Sofie Wulff Eilertsen  –  Doctoral Research Fellow

Birgitte Gladsø Tøndel

Oda Gabrielle R. Leknessund  –  MD PhD student (Forskerlinja)

Vårin Eiriksdatter Wikan  –  MD PhD student (Forskerlinja)

Asbjørn Lund Onsaker  –  MD PhD student (Forskerlinja)

Nikolai Hagensen Eide  –  MD PhD student (Forskerlinja)

Camilla Langholm  –  MD PhD student (Forskerlinja)

Anna Yang Arntzen  –  MD PhD student (Forskerlinja)

Mathias Haugmo Storvand  –  MD PhD student (Forskerlinja)

Solveig Marie Valderhaug  –  MD PhD student (Forskerlinja)

Inga Røstvold  –  MD PhD student (Forskerlinja)