Musings about the role dietary fats after 40 years of fatty acid research.

Since the 1950's nutrition recommendations have focussed on the replacement of saturated fats in the diet with polyunsaturated fats, a strategy that continues to this day. Despite supporting evidence from clinical trials for the advantages of Mediterranean diets, there has been less attention paid to the role of monounsaturated fats. It has been known for many years that diets high in linoleic acid (LA) compete for the incorporation of omega 3 fatty acids into tissues. What is also clear is that diets rich in LA are not free from concerns and the discovery of oxlams, oxygenated derivatives of LA, having potent inflammatory effects may help us question the dogma of LA rich diets. Given that dietary oleic acid a prime constituent of Mediterranean diets can be metabolised to Mead acid (ETrA) has in the past been a cause for concern, but new data showing the anti-inflammatory effects of ETrA suggest that there is a need for further research about the benefits of monounsaturated oils on human health. Finally, there is a need to re-examine how dietary fats are monitored in clinical studies. The current method of focussing on esterified fatty acids may be too insensitive to detect clinically important changes.