Vegetable oils, also known as polyunsaturated fatty acids or PUFAs, may not be as healthy as nutrition experts believe. For decades people have been told to cook with corn, safflower or sunflower oil to lower their cholesterol levels and risk of heart disease.
Health professionals, including cardiologists, internists, family doctors, nurse practitioners, physician assistants registered dieticians and nutritionists warned patients that saturated fat and cholesterol were the enemies and would cause heart attacks, strokes and premature death.
For over 50 years American cooks imagined that frying eggs in butter for breakfast would be the equivalent of walking the gang plank to heart disease. Instead, sugar-sweetened breakfast cereal with skim milk and a couple of slices of banana were considered heart healthy. Cream in coffee was believed to be a decadent indulgence while artificial coffee creamer loaded with trans fats was thought to be a safer alternative. Were such recommendations wrong?
The BIG Experiment:
A new analysis of old data just published in the BMJ is throwing doubt on the old dietary dogmas. The original research, called the Minnesota Coronary Experiment, was conducted over five years, beginning in 1968. It was a randomized controlled trial. That design is rare for dietary studies, partly because it is so hard to implement.
The participants were 9,000 individuals in mental institutions and a nursing home. Those assigned to the intervention were fed a diet lower in saturated fat than the average American diet of the time. Their food was cooked in corn oil and the subjects were given corn oil margarine, considered heart healthy fat.
The control group was given a typical American diet with the usual amounts of butter and meat as sources of saturated fat. Investigators Ivan Frantz and Ancel Keys followed up on participants’ cholesterol levels and conducted autopsies on those who died. They were looking specifically for evidence of clogged heart arteries and heart attacks.
The BIG Fat Lie:
Ancel Keys and his colleagues could not have been happy with the results of their study, which ended in 1973. They waited until 1989 to publish their findings.
Even then, they obfuscated and spun the data to try and support their diet-heart hypothesis that cholesterol and saturated fat were harmful to the heart. They never published the results of the autopsy part of the study, perhaps because they were afraid of what it might do to the hypothesis.
Now the Truth is Out.
More than three decades later, on April 13, 2016, a new analysis of the original data was published in the BMJ. It shows that the corn oil-consuming subjects had lower cholesterol levels than the people eating high saturated fat diets, but their mortality statistics were no better. In fact, older participants were actually more likely to die during the study time frame if they were in the corn oil group.
Even more alarming, those eating lots of vegetable oil were more likely to show signs of a heart attack upon autopsy than those eating more saturated fat. There was no difference in clogged arteries between the groups.
These results are consistent with those from an Australian study conducted around the same time. The investigators were able to analyze the previously unpublished data from that one, termed the Sydney Diet Heart Study. Those data also showed no survival advantage for people consuming corn oil instead of the more common forms of saturated fat such as bacon or butter.
Doing a U-Turn on the Diet-Heart Hypothesis:
Perhaps it is time to reconsider the lipid hypothesis of heart disease. There are now a number of controlled trials that pretty much put the nail in the coffin of the vegetable oil recommendations of the last 50 to 60 years. We’ve already buried trans fats, so maybe we should rethink many, if not most, of the dietary dogma that has not been supported by decent data.
Learn more about the saturated fat mistake in these articles:
“Has the Flip-Flop on Saturated Fat Made Your Head Spin?”
“Are Saturated Fat, Cholesterol and Salt Really Dietary Demons””
“No Evidence Found Linking Saturated Fat Consumption to Heart Disease”
You can read more about other dietary approaches to keeping your heart healthy in our book, Best Choices From The People’s Pharmacy.
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