Health benefits of omega-6 oils questioned in new research

Here’s something you haven’t read in approximately 24 hours. It’s a medical study debunking a previous study’s claims.

Published in last week’s British Medical Journal, an explosive evaluation of an old study suggests omega-6 oils may actually increase the risk of heart attack by a small margin.

Omega-6 vegetable oils including sunflower and corn oil have been lauded as a “healthier” option to saturated animal fats since the 1960s because of their ability to lower cholesterol, and ultimately, lower one's heart attack risk.

In fact, the University of Maryland Medical Centre lists omega-6s as “essential fatty acids” that humans can’t produce on their own, so they encourage its ingestion through food.

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However, the BMJ's new research takes a closer look at previous data from the Sydney Diet Heart Study. The new evaluation suggests the despite the ability of omega-6 fatty acids to lower cholesterol, they do not lower heart attack risk.

The old trials examined to come to this conclusion were conducted between 1966-1973 and followed 458 men between the ages of 30 to 59 with a history of cardiovascular disease.

Half the participants were given linoleic acid (a type of omega-6) in the form of safflower oil and safflower oil polyunsaturated margarine. The other half of the study participants did not receive anything.

"The group that was randomized to omega-6 from safflower oil, they had increased risk of death from all causes as well as death due to coronary heart disease and death due to cardiovascular disease and this was despite significant cholesterol lowering," study author Dr. Christopher Ramsden, a clinical investigator with the U.S. National Institutes of Health in Washington, tells CBC.

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The interesting thing about the timing of this new research is that Health Canada recently revised regulations regarding omega-6 vegetable oils.

The new rules now allow companies to slap nutritional labels on their food products that claim “replacing saturated fats with unsaturated fats including omega-6 vegetable oils” can can help reduce cholesterol levels.

Since the BMJ released its new research, some health experts have been putting pressure on Health Canada to revise its vegetable oil policy.

CBC spoke with Richard Bazinet, a nutrition professor at University of Toronto who specializes in fatty acids, and he urged Health Canada to “re-evaluate” its policy.

"There's absolutely no evidence to suggest that we should increase more omega-6s, when we have the American Heart Association and a potential health claim in Canada saying yes, this is something we should consume more of, it’s absolutely backwards with the evidence," he says.

While pressure mounts on the government agency to reconsider its stance, the Vegetable Oil Industry of Canada has released a stern press release blasting the CBC story for its “misleading” claims.

“This paper contains a new analysis of old data recovered from the Sydney Diet Heart Study (SDHS) conducted in 1969-73. That study's participants, men with a history of cardiovascular disease, were tested with very high doses of omega-6 at 15 per cent of daily energy, which is more than three times the intake level of Canadians,” reads the industry statement.