Dietary Linoleic Acid and Risk of Coronary Heart Disease: A Systematic Review and Meta-Analysis of Prospective Cohort Studies

Study Questions:

What is the relation between dietary linoleic acid (LA) intake and coronary heart disease (CHD) risk?

Methods:

The authors searched MEDLINE and EMBASE databases through June, 2013, for prospective cohort studies that reported the association between dietary LA and CHD events, and utilized unpublished data from cohort studies in a previous pooling project. They pooled the multivariate-adjusted relative risk (RR) comparing the highest with the lowest categories of LA intake using fixed-effect meta-analysis.

Results:

There were 13 published and unpublished cohort studies with a total of 310,602 individuals and 12,479 total CHD events, including 5,882 CHD deaths. Comparing the highest to the lowest category, dietary LA was associated with a 15% lower risk of CHD events (pooled RR, 0.85; 95% confidence interval [CI], 0.78-0.92; I² = 35.5%) and a 21% lower risk of CHD deaths (pooled RR, 0.79; 95% CI, 0.71-0.89; I² = 0.0%). A 5% of energy increment in LA intake replacing energy from saturated fat intake was associated with a 9% lower risk of CHD events (RR, 0.91; 95% CI, 0.86-0.96) and a 13% lower risk of CHD deaths (RR, 0.87; 95% CI, 0.82-0.94).

Conclusions:

In prospective observational studies, dietary LA intake is inversely associated with CHD risk in a dose-response manner. These data provide support for current recommendations to replace saturated fat with polyunsaturated fat (PUFA) for primary prevention of CHD.

Perspective:

The degree of benefit of CHD event reduction related to dietary LA is impressive. The most important and unanswered question related to replacing dietary saturated fat with PUFAs including LA is the optimal ratio of n-6 (LA) to n-3 (e.g., fish and nut sources). Diets high in LA might reduce the benefits of omega-3 PUFAs on CHD, and there are data suggesting that LA may increase cancer risk because of increasing lipid peroxidation.

Clinical Topics: Dyslipidemia, Prevention, Lipid Metabolism

Keywords: Neoplasms, Dietary Fats, Linoleic Acids, Lipid Peroxidation, Nuts, Coronary Disease, Risk Factors, Primary Prevention, MEDLINE


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