According to a new analysis of existing research on fatty acids and heart risks, there is little evidence to support recommendations to consume more polyunsaturated fat and less saturated fat to reduce heart disease.

The researchers conducted a systematic review and meta-analysis of studies available in medical-journal databases through July 2013 that included the following: 32 prospective observational studies that concerned fatty acids from food intake; 17 prospective observational studies involving fatty acid biomarkers found in blood; and 27 randomized controlled trials that investigated fatty acid supplements. All eligible studies evaluated these factors with respect to coronary events. The resulting data pool comprised more than 600,000 subjects globally and involved both healthy subjects and subjects with cardiac disease.

In the 32 studies with subjects who reported their consumption of foods from fatty acids, the researchers compared the top third of subjects with the bottom third (in terms of fatty acid intake). They found insignificant associations between coronary events and the intake of long chain [omega]-3 and [omega]-6 polyunsaturated fatty acids, saturated fats, and monounsaturated fats.

The 17 studies that examined blood biomarkers of fatty acids showed that two specific circulating saturated fatty acids, palmitic and stearic acids, had positive but not statistically significant associations with cardiovascular disease. Margaric acid (found in milk and dairy products), however, was significantly associated with a lower risk of coronary events. No other fatty acid biomarker had a statistically significant effect on coronary risk.

The 27 randomized controlled trials analyzing the effect of fatty acid supplements on coronary risk involved more than 100,000 subjects; 5,726 had a coronary event. Of the subjects who had taken linolenic acid or [omega]-3 or [omega]-6 polyunsaturated fatty acid supplements, none had significant reductions in coronary risk, as compared with control subjects.

The authors proposed that in light of the lack of significant correlations between polyunsaturated and saturated fats and coronary risk, current dietary guidelines may need to be reevaluated and revised to better reflect the research evidence.

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