Linoleic acid and heart infarct]

A re-analysis of the Sydney Diet Heart Study (Ramsden et al., BMJ 2013) suggested that a diet high in linoleic acid increased the risk of coronary heart disease. The authors ascribe this to a lack of the omega-3 fatty acid, alpha-linolenic acid, in the oils and fats consumed. This argument has some weaknesses. Mortality in the linoleic acid group was 38 cases versus 27 in the control group (or 35 versus 28, or 39 versus 28; sources differ). The difference was significant in the current, though not in the original, publication. Conceivably, application of multiple statistical models led to chance significances. Additionally, the fats consumed by subjects in the intervention group were high in trans fats, which may have increased risk. Finally, a large recent clinical trial failed to show any benefit of linolenic acid. The conclusion is, therefore, that this re-analysis provides insufficient evidence to justify changes in current dietary recommendations.