By Uffe Ravnskov MD
Ask any scientist in this area to list the names of those who have created the diet-heart idea and nine out of ten probably put the name Ancel Keys on the top. Keys had no clinical experience; he was an American professor in physiology. Maybe this explains the many curious conclusions he has drawn from his studies about heart disease.
One of his first contributions in this area of science was a paper from 1953 where he stated that heart disease was caused by too much fat in the diet. As an argument he used a diagram showing the association between fat consumption and heart mortality in six countries. It looked very convincing, because all observations were in accord.
On top were the figures from the US; at the bottom those from Japan. In the US people ate five times more fat than in Japan, and heart mortality was fifteen times higher. The data from the other countries lay all between forming a beautiful curve starting in the lower left corner and ending in the upper right. (7)
But Keys' paper was a fake. At that time information was available from twenty-two countries. This is what two American scientists revealed four years later.(8) Their conclusion was clear: "The apparent association is greatly reduced when tested on all countries for which data are available instead of the six countries used by another investigator."
The death rate from coronary heart disease in Finland, for instance, was seven times that of Mexico, although fat consumption in the two nations was almost the same. But nobody reacted, and his paper is still used by to-day's experts as an argument for their dietary guidelines.
Also used is another of Keys´ papers, called Seven Countries.(9) In that study he followed sixteen population groups in seven different countries and from his observations he concluded that one of the most important factors behind heart disease was too much saturated fat in the diet.
The reason? If you eat too much saturated fat, he claimed, your cholesterol goes up. This was what he and other researchers had seen in dietary experiments where they had given healthy people various amounts of fats.
When they gave them much saturated fat and little polyunsaturated fat, the fat that dominates in most vegetable oils, their cholesterol went up. And when they did the opposite, cholesterol went down. Their message was swallowed by the rest of the world. Anyone who questions this sacred dogma today is considered a quack.
His idea was questioned by Raymond Reiser, an American professor in biochemistry, who pointed to several errors in Keys' argumentation.(10) Instead of giving the test individuals natural saturated fat from animal food in the experiments, many authors had used vegetable oils saturated by hydrogenation, a process that also produces trans fat, and today we know that trans fat indeed causes cholesterol to go up. In addition, when cholesterol went up, researchers attributed the effect to high intakes of saturated fat when in fact it could have been due to low intakes of polyunsaturated fat, and vice versa.
Saturated fat doesn't raise cholesterol
What definitely argues against an adverse cholesterol response from saturated fat is the outcome of modern dietary trials where scientists have used a diet low in carbohydrates with a high content of saturated fat to combat diabetes and/or obesity.
By avoiding bread, potatoes, cakes, cookies, candies and soft drinks these scientists have achieved amazing results. In a few days many diabetic patients were able to skip their insulin and the effect on body weight was much better than those who followed the dietary guidelines.(11)
And here comes the surprising finding. Even if the diet covered 20-50 percent of calories with saturated fat, nothing happened with the patients' cholesterol, a finding that has been confirmed in many trials.(12)
And there is more. Already in the eighties American researcher Ronald Krauss found that the most useful risk marker, the best predictor of heart disease among the blood lipids, wasn't the total amount of cholesterol in the blood, neither the bad guy LDL cholesterol, but a special type of LDL particle, the small, dense ones. The most surprising finding was that if somebody ate a high saturated fat diet, the number of these small, dense LDL particles decreased.(13)
For six years Indian researcher Malhotra registered how many died from a heart attack among the more than one million employees of the Indian railways.
According to Malhotra's report employees who lived in Madras had the highest mortality. It was six to seven times higher than in Punjab, the district with the lowest mortality, and they died at a much younger age. But people in Punjab ate almost seventeen times more fat than people from Madras and most of it was animal fat. In addition they smoked much more.(14)
Many experts must have been skeptical of Malhotra's result: "How is that possible? How many of you believe in such nonsense? Raise your hands!"
Maybe they hadn't read Malhotra's paper? But they did know the Japanese migrant study, because it is used again and again in the official papers as one of their strongest arguments.
At the time of that study Japanese ate little animal fat, their cholesterol was low, and coronary heart disease was rare, as it is still today. It is of course tempting to link them together and use it as an argument for avoiding animal fat, in particular with the results from the migrant study in hand.
What the investigators found was that when Japanese people emigrated to the US, their cholesterol went up and they died more often from heart disease, and at that time saturated fat was a major ingredient of their new diet. Therefore, isn't this a wonderful demonstration of the importance of avoiding saturated fat?
One of the members of the research team was Dr. Michael Marmot, a British researcher who has taught us much about the influence of stress and social factors on heart disease. Marmot found that it was not the food that raised the Japanese emigrants' cholesterol, nor the higher cholesterol that increased their risk of heart disease.
He could state that with certainty because Japanese emigrants who maintained their cultural traditions kept their low risk of heart attacks, although their cholesterol increased as much as in those who adopted a Western lifestyle.
The most striking of Marmot´s findings was that emigrants who stuck with the Japanese traditions but preferred the high fat American diet ran a smaller risk of heart disease than those who adopted the American way of life but adhered to the typical lean, Japanese diet. Isn't this a wonderful demonstration of the unimportance of avoiding saturated fat? (15)
But let me return to Seven Countries. Apparently very few have read the full 260 pages report, because if you do that meticulously, as I have done, you will soon discover findings that are at odds with Keys´ idea that saturated fat causes heart disease.
For instance, although the intake was almost equal in the Finnish population groups from Turku and North Karelia, heart mortality was five times higher in North Karelia than in Turku. And although the intake was equal on the two Greek islands Crete and Corfu, heart mortality was almost seven times higher on Corfu than on Crete.
Dr. Uffe Ravnskov MD
Author of "The Cholesterol Myths" and "Fat and Cholesterol are Good for You"
Creator and spokesman of THINCS, "The International Network of Cholesterol Skeptics"
Saturated Fat is Good for You - by Uffe Ravnskov MD - Part 3 of 3
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Updated August 2011