Key Findings:
This systematic review and meta-analysis of data from long-term prospective observational studies, examined associations between dietary and biomarkers of omega 3 and 6 fatty acids with coronary outcomes. The findings do not support cardiovascular health outcomes with high consumption of long-chain n-3 and n-6 and polyunsaturated fatty acids. The data showed nonsignificant associations in prospective studies of coronary disease and dietary intake of long-chain n-3 and n-6 polyunsaturated fatty acids. The meta-analysis of randomized trials of these fatty acid supplements suggests they do not significantly reduce the risk for coronary outcomes. Only a relatively small number of trials investigated alpha-linolenic acid and showed a null association with coronary heart disease outcomes.
ABSTRACT:
Background: Guidelines advocate changes in fatty acid consumption to promote cardiovascular health. Purpose: To summarize evidence about associations between fatty acids and coronary disease. Data Sources: MEDLINE, Science Citation Index, and Cochrane
Central Register of Controlled Trials through July 2013. Study Selection: Prospective, observational studies and randomized, controlled trials. Data Extraction: Investigators extracted data about study characteristics and assessed study biases. Data Synthesis: There were 32 observational studies (530 525 participants) of fatty acids from dietary intake; 17 observational studies (25 721 participants) of fatty acid biomarkers; and 27 randomized, controlled trials (103 052 participants) of fatty acid supplementation. In observational studies, relative risks for coronary disease were 1.02 (95% CI, 0.97 to 1.07) for saturated, 0.99 (CI, 0.89 to 1.09) for monounsaturated, 0.93 (CI, 0.84 to 1.02) for long-chain n-3 polyunsaturated, 1.01 (CI, 0.96 to 1.07) for n6 polyunsaturated, and 1.16 (CI, 1.06 to 1.27) for trans fatty acids when the top and bottom thirds of baseline dietary fatty acid intake were compared. Corresponding estimates for circulating fatty acids were 1.06 (CI, 0.86 to 1.30), 1.06 (CI, 0.97 to 1.17), 0.84 (CI, 0.63 to 1.11), 0.94 (CI, 0.84 to 1.06), and 1.05 (CI, 0.76 to 1.44), respectively. There was heterogeneity of the associations among individual circulating fatty acids and coronary disease. In randomized, controlled trials, relative risks for coronary disease were 0.97 (CI, 0.69 to 1.36) for alpha-linolenic, 0.94 (CI, 0.86 to 1.03) for long-chain n-3 polyunsaturated, and 0.89 (CI, 0.71 to 1.12) for n-6 polyunsaturated fatty acid supplementations. Limitation: Potential biases from preferential publication and selective reporting. Conclusion: Current evidence does not clearly support cardiovascular guidelines that encourage high consumption of polyunsaturated fatty acids and low consumption of total saturated fats. (Authors abstract)
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