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January 1, 1958

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Insignificant results and poor methodology don't seem to matter for Finnish Mental Hospital study which was "the best possible proof" that saturated fat is unhealthy.





Finnish Mental Hospital study

Nina Teicholz


Important Text:

A third famous clinical trial that is cited again and again is the Finnish Mental Hospital study. I first heard about this study from a top nutrition expert who assured me that it was really “the best possible proof” that saturated fat is unhealthy.

In 1958, researchers seeking to compare a traditional diet high in animal fats to a new one high in polyunsaturated fats selected two mental hospitals near Helsinki. One they called Hospital K and the other, Hospital N. For the first six years of the trial, inmates at Hospital N were fed a diet very high in vegetable fat. Ordinary milk was replaced with an emulsion of soybean oil in skim milk, and butter was replaced by a special margarine high in polyunsaturated fats. The vegetable oil content of the special diet was six times higher than in a normal diet. Meanwhile, inmates of Hospital K ate their regular fare. Then the hospitals swapped, and for the next six years, Hospital K inmates got the special diet while Hospital N returned to their normal one.

In the special-diet group, serum cholesterol went down by 12 percent to 18 percent, and “heart disease was halved.” This is how the study is remembered and is the conclusion that the study directors, Matti Miettinen and Osmo Turpeinen, themselves drew. In a population of middle-aged men, they said, a diet low in saturated fats “exerted a substantial preventive effect upon coronary heart disease.”

But a closer look reveals a different picture. Heart disease incidence (which the investigators defined as deaths plus heart attacks) did go down dramatically for the men at Hospital N: there were sixteen such cases among men on the normal diet compared to only four on the special diet. But the difference found in Hospital K was not significant. Nor was any difference observed among the women. The biggest problem with the study, however, was that, like the subjects in the LA Veterans Trial, its population was a moving target. With admissions and discharges over the years, the composition of the groups changed by half. A shifting population means that an inmate in the group who died of a heart attack might have been admitted three days earlier and the death would have had nothing to do with his diet; and, vice versa, a patient who was released might have died soon thereafter but would not have been recorded in the study.

This and other design problems were so great that two high-level NIH officials together with a professor at George Washington University felt moved to criticize the study in a letter to The Lancet asserting that the authors’ conclusions were too statistically weak to be used as any kind of evidence for the diet-heart hypothesis. Miettinen and Turpeinen acknowledged that their study design was “not ideal,” including the fact that the study population was far from stable, but asserted in their defense that a perfect trial would be “so elaborate and costly . . . [that it] may perhaps never be performed.” Their imperfect trial, meanwhile, would have to stand: “we do not see any reason to change or modify our conclusions,” they wrote. The research community accepted this “good-enough” reasoning, and the Finnish Mental Hospital study earned a spot as one of the linchpins of evidence for the diet-heart hypothesis.

Nina Teicholz - Page 77

Topics: (click image to open)

Low Fat / Low Cholesterol Study
Diet-Heart Hypothesis
The diet-heart hypothesis, also known as the lipid hypothesis, proposes that there is a direct relationship between dietary fat intake, particularly saturated fat and cholesterol, and the development of heart disease. It suggests that consuming high amounts of these fats leads to an increase in blood cholesterol levels, specifically low-density lipoprotein (LDL) cholesterol, which in turn contributes to the formation of atherosclerotic plaques in the arteries. Some consider this hypothesis nothing more than wishful thinking.
Cholesterol is an animal based molecule that forms cell membranes. It's a lipid known as a sterol. Cholesterol is found in all animal foods and is healthy to eat, despite the opinions set forth by the diet-heart hypothesis. Lipoproteins carry cholesterol as well as other lipids.
Fat is a term used to describe a group of compounds known as lipids, which are organic molecules made up of carbon, hydrogen, and oxygen atoms. Fats are an essential part of our diet and play important roles in our bodies. Animal fats with low linoleic and arachidonic acids are preferred.
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