Dietary intake of marine n‐3 polyunsaturated fatty acids and future risk of venous thromboembolism

BACKGROUND: Studies on the association between long‐chained n‐3 polyunsaturated fatty acids (n‐3 PUFAs) and risk of venous thromboembolism (VTE) are conflicting, potentially due to challenges related to assessment of n‐3 PUFA intake and changes in diet during follow‐up. OBJECTIVES: To investigate whether dietary intake of marine n‐3 PUFAs was associated with risk of incident VTE in a population‐based cohort with repeated assessments of n‐3 PUFA intake. METHODS: We recruited 21 970 participants (after excluding 7570 with incomplete data) from the fourth (1994‐1995) and sixth (2007‐2008) surveys of the Tromsø Study, and recorded incident VTEs up to 2016. Intake of n‐3 PUFAs was computed from self‐reported consumption of fat and lean fish, fish spread, and supplements. Cox proportional hazards regression models with n‐3 PUFA intake as a time‐varying variable were used to calculate hazard ratios (HRs) with 95% confidence intervals (CIs) for VTE across quartiles (Q) of n‐3 PUFA intake. RESULTS: There were 541 incident VTEs during follow‐up. Compared to Q1, subjects in Q2‐4 had 22%‐26% lower risk of VTE (HR Q2 0.74, 95% CI 0.57‐0.96; HR Q3 0.77, 95% CI 0.59‐0.99; HR Q4 0.78, 95% CI 0.61‐1.00). The association was most pronounced for provoked VTE, particularly provoked pulmonary embolism (PE), with risk estimates of 0.42 (95% CI 0.25‐0.72), 0.40 (95% CI 0.23‐0.68), and 0.61 (95% CI 0.38‐0.96) for Q2‐4, respectively. CONCLUSIONS: Dietary intake of marine n‐3 PUFAs was associated with a lower risk of VTE, particularly provoked PE. The association displayed a threshold pattern and suggested a protective effect of an n‐3 PUFA intake ≥4.7 g/week.