Ont. study casts doubt on some veg oils’ heart-healthiness

Health Canada will want to rethink the “heart-healthy” claims it allows for food-grade oils made from corn and safflower, new research from Ontario suggests.

Dr. Richard Bazinet of the University of Toronto’s nutritional sciences department and Michael Chu of London-based Western University’s Lawson Health Research Institute warn the heart-healthiness claim for vegetable oils actually depends on their ratio of two kinds of polyunsaturates fatty acids.

The Toronto research rips the now-common wisdom that replacing saturated animal fats with polyunsaturated vegetable oils generally helps reduce serum cholesterol levels and prevent heart disease.

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Health Canada’s Food Directorate since last year has allowed food processors to label all such oils, and foods made with those oils, as providing “a reduced risk of heart disease by lowering blood cholesterol levels.”

However, the Ontario study’s evaluation finds “allowing a health claim for vegetable oils rich in omega-6 linoleic acid but relatively poor in omega-3 α-linolenic acid may not be warranted,” Bazinet and Chu wrote in a study posted online in the Canadian Medical Association Journal.

Continuing to allow such a claim, they wrote, may be “misguided” and they instead suggest the claim be tweaked “such that foods rich in omega-6 linoleic acid but poor in omega-3 α-linolenic acid be excluded.”

That suggestion would strike such claims for corn and safflower oil — both rich in omega-6 linoleic acid but containing almost no omega-3 α-linolenic acid and thus “not associated with beneficial effects on heart health,” Bazinet said Monday in a University of Toronto release.

Canola and soybean oils, which contain both linoleic and α-linolenic acids, are the most common forms of vegetable oil in the Canadian diet, they note.

Omega-6 linoleic acid alone, they note, is found in corn and safflower oils as well as foods such as mayonnaise, creamy dressings, margarine, chips and nuts.

In their CMA Journal piece, Bazinet and Chu cite a study published in February, in which an “intervention group” replaced saturated fat with sources of safflower oil or safflower oil margarine.

The intervention group in the February study had serum cholesterol levels “significantly decreased” — down about eight to 13 per cent — compared to baseline and the control group, which is “consistent with the health claim,” they wrote.

However, Bazinet noted in the university release, “rates of death from all causes of cardiovascular disease and coronary artery disease significantly increased in the treatment group.”

“When the new results were added to a meta-analysis, the net result was a borderline 33 per cent increase in heart disease risk for oils rich in omega-6 and poor in omega-3, with absolutely no evidence of a benefit as is implied by the health claim,” Bazinet said. — AGCanada.com Network

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