Keep eating that dukkah. That’s the message from a study published this week that found people with diets rich in omega-6 fats, found in nuts and seeds, are up to 43 per cent less likely to develop type 2 diabetes.
Lead author Dr Jason Wu, of The George Institute for Global Health in Sydney, said “our findings suggest that a simple change in diet might protect people from developing type 2 diabetes”.
Working out how diet is linked to lifestyle diseases is notoriously difficult, often because it relies on people keeping diet records. And people don’t keep good diet records. To get round this, the researchers only looked at studies which measured levels of omega-6 molecules in the blood.
Wu and colleagues from around the world combined data from 20 studies involving 39,740 healthy adults from 10 countries. There were 4,347 new cases of diabetes over time, but fewer of those cases occurred in people with high blood levels of linoleic acid – the major omega-6 fat.
Writing in The Lancet Diabetes & Endocrinology, where the study was published, Italian scientist Dr Gabriele Riccardi from Federico II University said that the amount of extra linoleic acid which was protective was equivalent to eating one portion of nuts, or one spoonful of sunflower oil a day.
Professor Peter Clifton from the University of South Australia told the Australian Science Media Centre that “we are faced with an increasing incidence of type 2 diabetes which has mostly been attributed to increasing obesity. But one contributing factor, especially in Australia, is a declining use of margarines and oils which are rich in linoleic acid.”
It is well known that eating plenty of nuts and seeds is good for the heart, and dietary guidelines for heart health recommend foods rich in linoleic acid. But much less is known about how omega-6 affects diabetes.
According to Professor Clifton “this new data shows that it is likely that consuming margarines and oils rich in linoleic acid will not only reduce the incidence of heart attack, it will reduce the incidence of type 2 diabetes.”
Some previous studies had suggested that omega-6 fats might, in fact, have negative health effects. The theory was that linoleic acid might be converted to the inflammation-causing arachidonic acid, which could potentially raise the risk of diabetes. This has been taken seriously enough for French national guidelines to recommend that linoleic acid should make up no more than four per cent of energy intake.
However, such fears were not borne out in the study, where people with higher levels of arachidonic acid in their blood were no more likely to develop type 2 diabetes.
According to Dr Riccardi, the time is now ripe for a randomised medical trial to test whether foods high in linoleic acid can be used as a targeted intervention to prevent the development of type 2 diabetes.
This article also appears in Science Deadline, a weekly email newsletter from the Australian Science Media Centre.