Findings from the most recent review comparing the effects of fatty acids on heart disease do not agree with the current US nutritional recommendations. Current recommendations encourage replacing saturated fat intake with monounsaturated and polyunsaturated fats to reduce heart disease risk. The meta-analysis, published in the Annals of Internal Medicine, finds no association of saturated fat intake with heart disease.
The new review is robust, including 600,000 individuals in 76 observational and randomized controlled studies from multiple countries. Many of the studies measured biomarkers of fatty acid consumption to confirm the validity of food questionnaires submitted by participants.
Contrary to US nutritional recommendations, the study did not find saturated fat consumption to be correlated with heart disease risk. Monounsaturated fat consumption also had no impact on heart disease risk.
Effects of polyunsaturated fatty acids were less clear. Consumption of omega-3 or omega-6 fatty acids was not significantly associated with altered risk of heart disease (although there was a trend of reduced heart disease with increased omega-3 consumption). However, when specific polyunsaturated fats in the blood were measured there were some significant correlations. High levels of circulating eicosapentaenoic acid (EPA) and docosahexaenoic (DHA) together produced a 25% reduction in heart disease risk. These are the omega-3 fatty acids found in fish oil. However, the review did not find an impact of supplementation with omega-3 fatty acids on heart disease risk in at-risk populations. The authors conclude that more studies of omega-3 fatty acids in healthy populations are needed to determine if they prevent heart disease.
The only type of fat in the study associated with an increased risk of heart disease was trans fat, which increased risk by 16%.
The authors conclude that the findings from their analysis do not support the US guidelines that encourage low consumption of saturated fats and that the recommendations may require reappraisal.
In summary, the only type of fat that we should avoid is trans fat. Trans fats are man-made and not present in nature. Natural fats, whether they come from animals or plants, do not appear to increase heart disease risk.
Food manufacturers often alter serving sizes to hide the presence of trans fat in their product. If you see an ingredient that is “hydrogenated” or “partially hydrogenated,” it is a trans fat and is best to avoid.