Do you worry about your cholesterol levels? Have you followed the nutrition advice of the American Heart Association to ban butter, embrace margarine, avoid eggs and use vegetable oil as your cooking fat?
The diet-heart hypothesis, which holds that saturated fat consumption increases cholesterol levels and heart disease, has been entrenched since the 1950s. What if it was all a big fat lie?
The Diet-Heart Hypothesis Now in Question:
Much of the evidence behind these dietary recommendations was carefully selected to support it. The champion was a charismatic physiologist named Ancel Keys.
Dr. Keys noted that during World War II when Europeans had little access to butter and eggs (or much of anything else), rates of heart disease fell. On the other hand, Midwestern American businessmen, who were very well nourished, were increasingly likely to suffer heart attacks. Based on the observation of long-lived people in southern Italy, he suggested that their Mediterranean diet was responsible.
That observation was on target, but the Mediterranean diet concept lost a lot in its translation into American menus. Olive oil, fish and many of the vegetables popular in Italy just seemed too foreign for many folks here. Instead, Ancel Keys zealously promoted corn oil instead of olive oil and margarine to replace butter.
The Selective Seven Countries Study:
In his Seven Countries study, he put forth the concept that people who ate the least saturated fat were protected from heart disease. He didn’t mention that he was selective in choosing which countries to include and which to ignore. For example, he left out France and Switzerland, where heart disease rates were low despite high fat diets.
Saturated Fat vs. Corn Oil:
Such epidemiological studies are considered less convincing scientifically than randomized controlled trials. But Keys also conducted a controlled trial in which corn oil replaced butter and other fats in the diet.
The Minnesota Coronary Experiment began in 1968 and ran for five years. Dr. Keys and his colleagues included more than 9,000 individuals in mental institutions and a nursing home. The subjects were served either standard institutional fare, which was high in saturated fat, or a diet high in polyunsaturated fatty acids (PUFAs derived from vegetable oil). Their cholesterol intake was also restricted.
This was to be the definitive study of its day, designed to prove that by controlling the diet carefully by reducing saturated fat and dietary cholesterol, adding vegetable oil and lowering blood cholesterol, it would be possible to drastically diminish heart disease. Dr. Keys and his colleague Dr. Ivan Frantz, Jr., imagined that the institutionalized control subjects eating a typical American diet high in saturated fat (from cheese, milk, butter and beef) would have higher cholesterol and substantially more heart disease.
To be perfectly clear, this was one of the biggest and best diet studies ever designed. Such an experiment would be so expensive today that it is unlikely it would be funded.
The Unexpected News About Saturated Fat and Cholesterol:
The patients who were given the “heart healthy” diet with corn oil did have significantly lower cholesterol levels in their blood (14% reduction), but they were no less likely to die from heart disease.
Although the study ended in 1973, it was not published until 1989 (Atherosclerosis, Vol 9, No 1 January/February). That is highly unusual for such an important clinical trial. We can only wonder why the results were delayed 16 years. The researchers could not have been very happy with the results. They were winning the hearts and minds of cardiologists and the American public and this data might have thrown a monkey wrench into the growing anti-cholesterol machinery.
Even then, they tried to put a positive spin on the data. The researchers suggested that if the study had only lasted longer, the results would have been more favorable. In their own words:
“Although this study did not show a statistically significant reduction in cardiovascular events or total deaths from the treatment diet, the authors suspect that it might have shown such a reduction if the period of treatment had been longer in persons in the age range likely to benefit.”
They reported “some favorable trends” in heart attacks for people between the ages of 35 to 39 and 45 to 55 but admitted that “the numbers are far too small to achieve statistical significance.” It is unlikely that the editors of a modern medical journal would let investigators get away with that sort of speculation.
Old Data, New Analysis:
The original 1989 publication in the journal Atherosclerosis left out a lot of fascinating information. It likely would have remained a secret had it not been for Christopher Ramsden, MD, at the National Institute of Health. He and his colleagues were able to recruit Dr. Robert Frantz, a cardiologist at the Cleveland Clinic, to visit the family home where his father had stored the original data before his death in 2009. There, in the basement, was a box containing the raw information from the “Minnesota Coronary Survey.”
A new analysis of the original data has at long last been published in the BMJ (April 13, 2016). It shows unequivocally that corn oil lowered cholesterol but did not lower death rates. In fact, the people on the “heart healthy” diet were more likely to die during the study than those on the standard American diet who were eating butter. If anything, the lower the cholesterol, the higher the death rate.
Despite this compelling new evidence and other recent data suggesting that the old diet-heart hypothesis should be discarded, health professionals are having a hard time giving up their advice that people should shun saturated fat and use vegetable oil instead. The wagons are being circled and the hope is that once the headlines fade people will forget this research.
The Bottom Line from The People’s Pharmacy:
One might imagine that when new information challenges old beliefs, scientists might re-evaluate their long-held recommendations. We live in a world where evidence-based medicine is considered the hallmark of good practice. But nutrition experts seemingly have a hard time reversing old recommendations.
The Minnesota Coronary Experiment was not the only randomized trial to compare vegetable oil to saturated fat. Dr. Ramsden managed to uncover long-lost data from an old Australian study from the 1960s. Like the Minnesota Coronary Experiment, key data were never analyzed.
In the Sydney Diet Heart Study, 458 men who had experienced a heart attack were recruited. Half continued on their usual high saturated fat diet. The other half got safflower oil instead. Just as in the Minnesota study, cholesterol levels dropped, but men getting the “heart healthy” diet were more likely to die from heart attacks (BMJ, online, Feb. 5, 2013). This study has seemingly disappeared without a trace from the memory banks of the diet dictocrats.
The one thing that Ancel Keys got right was that a Mediterranean-type diet is healthful. That does not mean cutting back on fat, though. Instead, this dietary pattern includes lots of vegetables, fruits, fish, nuts and beans, often prepared with generous amounts of olive oil.
We imagine that in 10 or 20 years dietary recommendations will change and people will be encouraged to eat full-fat yogurt, cook with coconut oil and consume lots of nuts that are high in fat. People will forget that for decades the so-called experts warned them to avoid eggs, butter and nuts.
To learn more about the risk factors we think are really responsible for heart disease and what can you can do to protect your heart, you may want to consider Best Choices from The People’s Pharmacy. See for yourself whether our long-standing recommendations make sense and why we think a “mood ring” from the 1970s might be just the ticket to avoid heart-damaging people.
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