PracticeUpdate.com
RESEARCH · August 26, 2014
TAKE-HOME MESSAGE
- In this meta-analysis of 13 cohort studies, the highest levels of dietary linoleic acid intake were associated with a 15% lower risk for coronary heart disease (CHD) and a 21% lower risk for CHD deaths compared with the lowest levels of intake.
- This analysis supports current recommendations to consume polyunsaturated fat in place of saturated fat for primary prevention of CHD.
Expert Comment
Primary Care
David Rakel MD, FAAFP
Linoleic acid and heart disease protection
The etymology of the word “linoleic” comes from the Greek “linon” (meaning flax) and “oleic” (meaning olive)—two foods that are rich in linoleic acid. The challenge with these polyunsaturated fats is that they spoil easily. For example, freshly ground flax seed is healthy, but, if it spoils, it becomes linseed oil, which is used to polish furniture (not healthy for ingestion), and, if that hardens, it becomes linoleum, which is used to line counters (definitely not healthy for ingestion). To preserve the lifespan of these vegetable oils, food scientists developed “partially hydrogenated” corn and soy oils, changing their composition to trans-fatty acids (also not healthy).
However, this meta-analysis shows that eating the fresh foods that contain linoleic acid is associated with a significant dose–response reduction in cardiovascular disease and deaths when these foods replaced carbohydrates (white foods and sugar) and saturated fat (red meat, dairy, and fried foods). Foods rich in linoleic acid include seeds and nuts, such as flax seeds, grape seeds, safflower oil, poppy seeds, sunflower seeds, evening primrose oil, olive oil, walnuts, pistachios, peanuts, corn, and soy. Put another feather in cap of the Mediterranean diet.
ABSTRACT
BACKGROUND
Prior studies on intake of linoleic acid (LA), the predominant n-6 fatty acid, and coronary heart disease (CHD) risk have generated inconsistent results. We performed a systematic review and meta-analysis of prospective cohort studies to summarize the evidence regarding the relation of dietary LA intake and CHD risk.
METHODS AND RESULTS
We searched MEDLINE and EMBASE databases through June, 2013 for prospective cohort studies that reported the association between dietary LA and CHD events. In addition, we utilized unpublished data from cohort studies in a previous pooling project. We pooled the multivariate-adjusted relative risk (RR) comparing the highest with the lowest categories of LA intake using fixed-effect meta-analysis. We identified 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 intervals (95% 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 for primary prevention of CHD.
Circulation
Dietary Linoleic Acid and Risk of Coronary Heart Disease: A Systematic Review and Meta-Analysis of Prospective Cohort Studies