We’re often told to substitute saturated animal fats for healthier vegetable oils, and while that is generally good advice, a new study suggests certain vegetable oils haven’t been shown to live up to the claim that they lower cholesterol or prevent heart disease.
In 2009, the governing body in charge of Canada’s food label regulation, the Food Directorate, approved a food industry request that the industry be able to label vegetable oils and foods containing these oils as being able to lower a person’s risk of heart disease by reducing so-called bad cholesterol. For brevity, we’ll call that the “healthy heart” claim. At the time this was uncontroversial as there was, and still is, a strong body of evidence to support the wider claim that when compared to saturated animal fats, these oils are better for our heart health.
However, research published this month in the Canadian Medical Association Journal (CMAJ) points out that this broad health claim may in fact be inappropriate because while on the whole vegetable fats tend to be better for our hearts, there isn’t evidence enough to suggest that all of those vegetable oils actually lower cholesterol. In fact, there is some evidence to suggest that certain vegetable oils may increase heart disease risk.
The research, conducted by Professor Richard Bazinet of the University of Toronto and Dr. Michael Chu, a heart surgeon at the London Cardiac Institute in Ontario, found that two oils in particular may not warrant the “healthy heart” label: corn and safflower oil. These oils are regularly used in Canadian food products like mayonnaise, creamy salad dressings, some margarines, and chips. The oils also regularly appear in many European and U.S. products.
The researchers carefully reviewed recent research into the effects of these oils. They found that the polyunsaturated vegetable oils are indeed rich in what is known as omega-6 linoleic acid. However, the oils are relatively poor in omega-3 alpha-linolenic acid. It turns out, it takes an abundance of both of these substances in order for the oil to have the proven cholesterol reducing health benefits.
What’s more, the researchers pointed out, a study released in February of this year in the British Medical Journal has suggested that though a diet rich in omega-6 can lower serum cholesterol levels, without omega-3 it might also increase the risk of coronary artery diseases. Now, the exact reason for this isn’t known, but researchers do think it may have something to do with certain other lifestyle factors, specifically those that increased what is known as “oxidative stress.” Those activities include smoking and consuming medium to large quantities of alcohol and as such may be compounding heart disease risk factors rather than creating them.
Nevertheless, the authors write, ”Careful evaluation of recent evidence, 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.”
The Vegetable Oil Industry of Canada (VOIC) has responded to this research by saying the study relies on old data and that its use of the 2013 study carries specific problems:
“[The 2013 study into omega-6 used] men with a history of cardiovascular disease, [who] 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,” the VOIC said in a statement to CTV News. “There is a substantial body of evidence supporting a recently approved health claim in Canada advising consumers to replace dietary sources of saturated fat with polyunsaturated and monounsaturated fats from vegetable oil to lower cholesterol.”
The VOIC unfortunately fails to answer the specific question of whether the broad “healthy heart” label for all vegetable oil-rich products is really appropriate given that it could be misleading, particularly for the demographic that might most want to reduce their heart disease risk: those with a history of heart disease problems.
What to Make of This Research?
To put this in perspective, it’s unlikely that corn and safflower oil products are going to dramatically increase health risks if those products are eaten in moderation by otherwise healthy adults. That’s not really the point, though. Accurate food labeling, especially around important topics like heart health, is essential. As such, the researchers say there isn’t yet evidence to support the claim that these two oils, corn and safflower oil, actually lower cholesterol and until there is, the products they contain should not be labeled as though this is a fact. As such, the researchers are calling on the Canadian food governing body to rethink the criteria for how it is labeling foods.
The study did find some positive news, too, and that should also be taken into consideration.
The two oils that are most common in the Canadian diet, canola and soybean oils, were found to contain both linoleic and α-linolenic acids and as such do provide the cholesterol reducing benefits that had been expected. Olive oil is also among the recommended oils that, when tested against other sources of fats, are shown to have significant health benefits.
This serves to reinforce that those seeking to reduce their so-called bad cholesterol levels need to look for products rich in both omega-3 and omega-6 in order to ensure they are getting the health benefits they are expecting. It also warns us against buying into what might be misleading health claims on product labels.
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