The long-standing recommendations to decrease the intake of saturated fat and increase intake of polyunsaturated fatty acids in order to reduce the risk of heart disease may warrant reconsideration, based on a study published online March 18 in Annals of Internal Medicine. The study found little evidence to support this guideline.

“[T]here is considerable variation in international guidelines about optimum amounts and types of fatty acid consumption,” explained the authors, led by Rajiv Chowdhury, MD, PhD, of the University of Cambridge in the United Kingdom.

The researchers conducted a meta-analysis of 72 studies including more than 600,000 participants that evaluated the association between dietary, circulating and supplement fatty acids and the risk of heart disease. They defined heart disease as fatal or nonfatal MI, coronary heart disease, coronary insufficiency, coronary death, angina, angiographic coronary stenosis or sudden cardiac death.

Comparing highest and lowest amounts of baseline dietary fatty acid intake, the relative risk (RR) of heart disease was 1.02 for saturated fatty acids, 0.99 for monounsaturated fatty acids, 0.93 for long-chain omega-3 polyunsaturated fatty acids, 1.01 for omega-6 polyunsaturated fatty acids and 1.16 for trans fatty acids. RRs for circulating fatty acids were 1.06, 0.94 and 1.05.

Data from randomized clinical trials for individual circulating fatty acids varied, however. RRs were 0.97 for alpha-linoleic acid, 0.94 for long-chain omega-3 polyunsaturated fatty acids and 0.89 for omega-6 polyunsaturated fatty acid supplementations.

Given the heterogeneous nature of some data and the statistical nonsignificance of other data, the authors argued that “[n]utritional guidelines on fatty acids and cardiovascular guidelines may require reappraisal to reflect the current evidence.”