Plain language summary
The importance of omega-3 fatty acids from fatty fish is frequently highlighted as a protective measure against artery plaque formation, and therefore protective against heart disease. The prospective, cross-sectional study of 3,900 individuals aimed to assess the impact of fish consumption or fish oil supplementation on artery plaque formation over a 7-year period. Using food frequency questionnaires, blood serum measures of fats and ultrasound imaging, the authors found no statistically significant association between fatty fish intake or fish oil supplements and artery plaque formation. Those who ate fish more than 3 times per week were found to have an increased risk of plaque formation when compared to those who ate less. Lean fish intake was associated with lower plaque formation however, and total fish consumption was inversely associated with triglyceride levels. The authors highlight some limitations of the study. They found that those who ate more fish tended to be older, male, smokers and have high inflammatory markers such as CRP. The cooking method used for the fish was also not assessed. Frying fish has been shown in other studies to affect the oils and their positive health benefits and could affect the results of this study. The authors conclude that the beneficial effects of fish consumption on artery plaque formation could be due to mechanisms other than omega-3 fat intake.
Abstract
BACKGROUND Whether long-chain n-3 PUFAs of marine origin have an anti-atherogenic effect in the general population has hardly been studied. In this population-based study, we hypothesized that fatty fish and fish oil intake protect against development of novel atherosclerotic plaques and is associated with reduced plaque size. METHODS We obtained questionnaire-based information on fish consumption and carotid ultrasonography from 3900 persons aged 45-74 years. The questionnaires were validated by measuring serum concentrations of PUFAs and triglycerides in a subgroup. At follow-up seven years later, 2983 (76%) went through a second ultrasound scanning. Logistic regression and general linear models were used to analyze the outcome (plaque presence and plaque area) as a function of fish consumption, including analyses stratified on fish oil supplements. RESULTS At baseline, lean fish intake < 1 time/week vs. 1-1.9 times/week was associated with risk of plaque (OR 1.34, 95% CI 1.03-1.76). Fatty fish intake and use of fish oil supplements were not statistically significantly associated with atherosclerosis at baseline. In persons without plaque at baseline, total fish consumption ≥3 times/week vs. 1-1.9 times/week was associated with risk of novel plaque (OR 1.32, 95% CI 1.01-1.73) and larger plaque area (1.76 mm2 vs. 1.46 mm2, p = 0.02) at follow-up. Adjustments for use of fish oil supplements had no impact on the associations, and no interactions were seen between total, fatty or lean fish consumption and fish oil intake. CONCLUSIONS We found no protective effect of fatty fish eating or fish oil supplements on atherosclerotic plaque formation or plaque area in a general population. Lean fish consumption was associated with a reduced risk for plaque in cross-sectional analysis, suggesting that the beneficial effects of fish consumption on atherosclerosis may be mediated through other mechanisms than n-3 PUFAs.
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