Omega-6 linked to obesity
Food manufacturers' careless use of omega-6 could be partly to blame for rising obesity levels, according to Reading University's professor of animal science Ian Givens.
Speaking at the British Nutrition Foundation's September conference on the Health Effects of Dietary Unsaturated Fatty Acid, Givens referred to a review compiled by Ailhaud et al (2006), which claimed food processors were in part responsible for the increase in obesity.
"What not many people tend to realise is that there has been a substantial increase in linoleic acid [omega-6]," says Givens. He criticises food processors for not taking into consideration the different types of fatty acids: "Polyunsaturates are being pushed as being better that saturates, which is fair enough, but without any thought as to what the best forms would be. There's been a big increase in sunflower oils and soya oils, which are very omega-6 rich."
Givens claims that if omega-6 is partly responsible for the increase in obesity, then enriching meat and milk with short chain omega-3 fatty acids (alpha linolenic acids or ALNA) derived from plants and nuts could have a more important role than it does now. This is because ALNA displaces omega-6.
ALNA might not be as nutritionally beneficial as longer chain fatty acids such as EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid), said Givens, but it is more sustainable because it comes from plants rather than marine sources. Reading University is currently working on the Real Economy and Land Use project, which is experimenting to see how ALNA levels in plants fluctuate depending on the time of year.
However, professor Tom Sanders of King's College London, believes that the omega-3/omega-6 ratio is not a key consideration when enriching ruminant products. "Whatever you do, ruminant products are always going to be high in saturated fats, unless you protect them biologically."
Sanders also points out how the flavour of these products is affected when fatty acid composition is altered. "It's quite well known that you change the taste of meat if you change the omega-3/omega-6 ratio," he says. "Spanish lamb tastes totally different to English lamb because one eats grass; the other eats grain."
