According to a new analysis, some vegetable oils that claim to be healthy may actually increase the risk of heart disease and Health Canada should reconsider cholesterol-lowering claims on food labeling.
Replacing saturated animal fats with polyunsaturated vegetable oils has become common practice because they can reduce serum cholesterol levels and help prevent heart disease. In 2009, Health Canada's Food Directorate, after reviewing published evidence, approved a request from the food industry to apply a heart disease risk reduction claim on vegetable oils and foods containing these oils. The label suggests "a reduced risk of heart disease by lowering blood cholesterol levels."
Careful evaluation of recent evidence buy Canadian researchers, however, suggests that 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.
Corn and safflower oil, which are rich in omega-6 linoleic acid but contain almost no omega-3 α-linolenic acid, are not associated with beneficial effects on heart health according to recent evidence.
The researchers cite a study published earlier this year "in which the intervention group replaced saturated fat with sources of safflower oil or safflower oil margarine (rich in omega-6 linoleic acid but low in omega-3 α-linoleic acid). They found that the intervention group had serum cholesterol levels that were significantly decreased relative to the start of the study and to the control group, which is consistent with the health claim." However, rates of death from all causes of cardiovascular disease and coronary artery disease significantly increased in the safflower oil group.
In Canada, omega-6 linoleic acid is found in corn and safflower oils as well as foods such as mayonnaise, margarine, chips and nuts. Canola and soybean oils, which contain both linoleic and α-linolenic acids, are the most common forms of oil in the Canadian diet. The scientists suggest that the health claim be modified such that foods rich in omega-6 linoleic acid but poor in omega-3 α-linolenic acid be excluded.
Source: CMAJ (Canadian Medical Association Journal), November 2013.
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