Health professionals have been misleading Americans about food for decades. We were told that cholesterol and fat were our enemies. Eggs, shrimp, nuts and olive oil were bad. That led the food industry to create carb-rich, highly processed foods containing sugar and fat substitutes. Margarine, canola oil and low-fat yogurt were supposed to be good for us. In the battle of health claims and culinary trends, cooking oil confusion has Americans grappling with mixed messages. Two recent articles have led to lots of reader questions. We will try to answer some of them in this new post.
Food Flip-Flops: Advice Keeps Shifting:
A lot has changed over the past few decades. Now eggs are OK. So are nuts. Margarine and low-fat yogurt sweetened with jelly are no longer magical health foods. But there is still tremendous cooking oil confusion. Readers want some clarity on what to choose.
In recent weeks we have written a lot about the dangers of a diet that is heavily weighted towards omega-6 fatty acids. If you missed these articles, here are two links:
What’s in Your Frying Pan? Omega-6 or Omega-3 Oils?
Seed oils from corn or soybeans have been linked to higher risk for cancer. Omega-3 oils from avocado, fish or olives seem safer
That article gives you a super-short overview of fatty acid biochemistry. You will learn about the difference between linoleic acid (LA) and ⍺-linolenic acid (ALA). The balance between these essential fatty acids is, in the opinion of many health experts, very important when it comes to inflammation within the body.
Here is another recent article on this general topic:
Are Some Vegetable Oils Worse than Saturated Fat? Colon Cancer?
For decades Americans have been told to eat lots of vegetable oils. They are also in our favorite crunch foods. Are there hidden dangers?
The War Over Oil Spreads Cooking Oil Confusion:
Pro-Omega-6 Fatty Acids:
I do not think it would be an exaggeration to describe the fatty acid furor as a war. Many of the most prestigious nutrition experts in the country have described polyunsaturated fatty acids (PUFAs) as our friends.
They maintain that seed oils rich in omega-6 fatty acids are absolutely not pro-inflammatory. They insist that they are anti-inflammatory. The recent articles above linking omega-6 fats to both colorectal and prostate cancer seem to challenge that view, however.
The pro-omega-6 factions are highly regarded academics. They insist that seed and vegetable oils such as sunflower, sesame, safflower, corn, soybean, and rapeseed (canola) are very good for you. They declare that using such oils will lower cholesterol and reduce the risk for heart disease.
Anti-Omega-6 Fatty Acids:
The renegades point out that seed oils must be heavily processed, with high heat and solvents as well as mechanical oil extraction, deodorization and several other steps. More importantly, though, they blame an imbalance in the ratio of omega-6 fatty acids to omega-3 fatty acids for many of our modern-day chronic diseases, including arthritis, hypertension, COPD and diabetes (BMC Endocrinology Disorders, Nov. 29, 2024).
They start by criticizing the research techniques of the father of the cholesterol-heart disease hypothesis, Dr. Ancel Keyes. For more than 70 years, a foundational pillar of health advice has been to avoid saturated fat and substitute vegetable oils instead. This was based on Ancel Keys’ theory of heart disease, which concluded that high intakes of saturated fat and cholesterol clogged coronary arteries.
The critics insist that Dr. Keys cherry-picked the countries he studied and the data he collected to reinforce his hypothesis. They point out that he excluded countries that might have challenged his theories. But his views took root.
Vegetable Oil and the Heart:
For decades, cardiologists and nutritionists have insisted that substituting vegetable oils instead of butter and cream would be helpful. Americans were urged to lower their total fat intake, which is why they were originally advised to avoid olive oil, with its saturated fat content, along with nuts and avocados.
Instead, they were told to use margarine, consume low-fat yogurt or skim milk and eat highly processed soy-based meat substitutes. How well did that program work to prevent heart disease? Did it have unexpected and unwelcome consequences?
The Sydney Diet Heart Study=Cooking Oil Confusion!
An inkling that vegetable oil program might have been flawed should have emerged in the 1970s. That’s when Australian scientists carried out a randomized controlled trial they called the Sydney Diet Heart Study. This experiment would have provided better evidence than the epidemiological data that Dr. Ancel Keys had collected.
Researchers divided 458 men who had recently suffered heart attacks into one of two groups. The first group continued its normal way of eating. The second group was provided with safflower oil and margarine made from safflower oil, which is rich in unsaturated omega-6 fatty acids.
When the study was published in 1978, the researchers did not analyze who was mostly likely to have had another coronary event or to die during the study. That seems to us, in retrospect, like a major oversight.
When the original data were rediscovered and analyzed decades later, they revealed that men in the experimental group getting safflower oil instead of butter were 60 percent more likely to die during the study (BMJ, Feb. 4, 2013).
Even worse, they were 75 percent more likely to die of coronary heart disease. That is, 16.3 percent of those in the experimental high-PUFA diet group succumbed compared to 10.1 percent of those consuming their usual butter-containing diet. If this had come out in 1978, experts might have reconsidered their enthusiasm for margarine during the 1980s and 1990s. If you look at the dates above, you will note that although the original data were made available in the 1970s, the key information was delayed for decades. Hmmmm.
The Corn Oil Study:
Even earlier, British scientists published a study in the British Medical Journal, June 12, 1965.
The Aims:
“Our purpose was to study the effects of prescribing a vegetable oil and a restricted fat diet to patients with ischaemic heart disease. The primary interest was in an unsaturated oil with a cholesterol-lowering effect.”
What They Found:
The trial was supposed to last three years, but the investigators stopped the study early because the preliminary results were dismal.
They wrote:
“The patients receiving the key treatment (corn oil) fared worse than those in the other two groups: two years from the start of treatment infarction or death had occurred in one-quarter more of the corn-oil than of the control group.
“It is concluded that under the circumstances of this trial corn oil cannot be recommended in the treatment of ischaemic heart disease.”
Somehow, these disappointing results disappeared without a trace.
Another Corn Oil Study with Disappointing Results:
The Minnesota Coronary Experiment almost didn’t see the light of day. Dr. Ancel Keys was one of the principal investigators. But the results did not support his cholesterol hypothesis of heart disease.
Perhaps as a result, the data languished without being published for decades. About 9,000 patients were randomized to eat a diet high in either omega-6 corn oil or saturated fat. As it turned out, those following the high-corn oil diet had lower cholesterol, but they did not live longer (BMJ, April 12, 2016).
Reducing the Cooking Oil Confusion:
We will not be able to resolve the battle over cooking oil in this post. What we can say, however, is that everyone seems to think olive oil is great. That includes Dr. Walter Willett, of the T.H.Chan School of Public Health at Harvard University. He is one of the country’s leading nutrition experts and epidemiologists. Although he defends omega-6 vegetable oils, Dr. Willett confided to us that his favorite cooking oil is olive oil. He also uses it on bread and in salads.
What fats are desirable? Monounsaturated fats such as those from olives and avocados appear to be healthful. Those are our first choices for cooking or salads. What’s our favorite? California Olive Ranch Extra Virgin Olive Oil.
Avocado oil is pricey! And most of it is refined. That said, ConsumerLab.com (our go-to website for such information) recommends Chosen Foods 100% Pure Avocado Oil. It’s the one we have in our cupboard. It works well for high-heat cooking like stir-fries. We also confess that we occasionally cook with butter.
Omega-3 fatty acids from fish and nuts also seem beneficial because they calm inflammation. It will take time for the nutrition establishment to incorporate this new evidence into its recommendations. In the meantime, people may want to cut back on processed foods, crunchy snacks and cooking with “light” oils such as corn, sunflower and safflower. Reading labels may be tedious, but it is the only way to make sure you are not getting more omega-6 than you want.
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