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.
Recent History
January 1, 1973
Keys dismisses Reiser's critique of his saturated-fat hypothesis.
Like Stamler, Keys allowed virtually no oxygen for debate. It’s astonishing, actually, to read his reaction to those who dared disagree with him. When Texas A&M professor Raymond Reiser wrote an extremely thorough and rigorous critique of the saturated-fat hypothesis for the American Journal of Clinical Nutrition in 1973, Keys began a twenty-four-page reply by saying that Reiser’s analysis “reminds one of the distorting mirrors in the hall of jokes at the county fair.” Keys’s tone throughout is relentlessly sneering: “This is a typical distortion,” he wrote, and “It would be difficult to pack more imprecision in a 16-word sentence”; “Resier pompously states . . . ,” “He completely ignores . . . ,” “Obviously, Reiser has no comprehension.”
Reiser was one of quite a few critics who had reexamined the important studies at the foundation of the diet-heart hypothesis. And he made a number of crucial observations that have recently resurfaced: he listed the many methodological problems undermining those early studies and noted that certain types of saturated fatty acids, such as stearic acid, which is the main one found in meat, demonstrated no cholesterol-raising effect at all. Keys’s response included rebuttals about specific problems, and although he agreed that stearic acid is “neutral,” he defended the cholesterol-raising properties of other types of saturated fats. Replying to Keys, Reiser wrote a short letter to the journal—reluctantly, he said, because “I feel I must give some rebuttal to the accusation that I have tried to smear the scientists whose papers I reviewed and that I have deliberately lied.”
-Nina Teicholz - The Big Fat Surprise - page 60
January 1, 1975
NiHonSan -- Epidemiologic studies of coronary heart disease and stroke in Japanese men living in Japan, Hawaii and California: prevalence of coronary and hypertensive heart disease and associated risk factors. (1975)
It turned out that the men who moved to California developed heart disease (as judged by abnormal electrocardiograph tests) twice as often as those in Hawaii or Japan.
Event Rich Text
January 1, 1978
Toward Healthful Diets
National Academy of Sciences says diet-heart hypothesis is still unproven.
Aside from Ahrens’s panel, there was one other group of nutrition experts who did not buy Hegsted’s argument about the science being good enough to justify these guidelines. This was the National Academy of Sciences, a private society created by Congress in 1863 to be a resource for advice on scientific matters. Its Food and Nutrition Board has been the most respected expert group in Washington, DC, on matters of nutrition since it was established in 1940, and it sets the Recommended Dietary Allowances (RDAs) of nutrients every few years. The board had actually been solicited by the USDA to write up a review of the Dietary Goals, but the contract was never signed. Someone canceled it, quite likely, as the magazine Science reported, because USDA officials had caught wind of the board’s lack of sympathy for the Senate’s new low-fat diet.
Unwilling to be silenced, the academy used its own funds to prepare a review. An academy panel went through the now-familiar process of reviewing those same studies that everyone else had been looking at. Its conclusion on the available diet-heart evidence, published in a report called Toward Healthful Diets, was that the studies had “generally unimpressive results.”
One of the more forceful points made by the academy was that Americans had been doing fairly well on their diet to date. The traditional diet was abundant in essential vitamins and high-quality proteins and was, as Gil Leveille, head of the Food and Nutrition Board, described it in 1978, “better than ever before and is one of the best, if not the best in the world.” The average height of the American male—a fairly reliable indicator of lifelong nutrition—had been fast rising throughout the first half of the twentieth century. Compared to countries with comparable statistics, Americans were among the tallest people on earth.XV
"Despite these generally unimpressive results, some organizations (American Heart Association, 1961. 1978; Select Committee on Nutrition and Human Needs, 1977) have recommended that dietary lipids be reduced from 40 percent to about 30 percent of calories and that the ratio of polyunsaturated to saturated fat (P:S ratio) be changed from the present value in the American diet of 0.4 to 0.5 to a ratio of about 1.0, in order to achieve lower serum cholesterol levels in the population generally Unfortunately, the benefit of altering the diet to this extent has not been established. As noted, other studies employing diets containing 35-40 percent of calories from fat and higher P:S ratios have shown equivocal effects on coronary disease and have been accompanied by a somewhat greater incidence of gastrointestinal disease (Ahrens, 1976)."
