Diet-Heart Hypothesis

4. Discussion. 

Since hypertension in man has been stated to be typically associated with increased incidence and severity of atherosclerosis (Katz and Stamler, 1953), it would be of interest to compare the incidence of hypertension in Eskimos with that of Whites although the interrelationship between hypertension and atherosclerosis is by no means clear. In a survey of 104 Alaskan Eskimos the author found that both the systolic and diastolic blood pressures were lower in Eskimos than in Whites of corresponding age. Eighty per cent of the recorded systolic blood pressures were below 116 mm Hg. and no systolic blood pressure higher than 162 mm was ever recorded in our "normal" Eskimo subjects. In a series of 117 Eskimo patients, only one of the patients had systolic blood pressure above 145 mm (a 60-year old woman having a blood pressure of 200/80 mm) (Rodahl, 1954). It may be noted in this connection that Alexander (1949) found hypertension to be practically non-existent among Aleuts, and his electrocardiographic and clinical examination of 296 Aleuts, including 23 above the age of 60, revealed almost no cardiovascular disease. 

Gotman et al. (1950) have found that some hypertensives show elevated plasma concentrations of Sf 10-20 lipoproteins even if the blood cholesterol concentration is normal, although these changes in the "giant molecule" levels are not correlated with the degree of hypertension. 

Very little is known regarding the plasma lipids in Eskimos, and the plasma lipid studies in Eskimos so far reported have yielded inconsistent data. This may not be surprising when considering the wide range of conditions, dietary and otherwise, encountered in the different groups of Eskimos. Corcoran and Rabinowitch (1937) who studied two groups of Canadian Eskimos, one group subsisting on a meat diet and one group subsisting on a mixed diet, found in both groups lower concentrations of plasma lipids and of cholesterol than the normal values for Whites, and the meat group had slightly higher plasma lipid levels than the group on a mixed diet. In this connection it may be noted that serum cholesterol in Whites is decreased in severe caloric undernutrition (Keys, 1953-b). Periods of semi-starvation may occur among the Eskimos, which thus may affect the blood lipid levels. Sinclair et al. ( 1949) have reported plasma lipid findings in the Canadian Eskimos that are similar to the figures considered normal in Americans. Wilber and Levine (1950) found moderately elevated plasma lipid levels of Alaskan Eskimos. It may also be noted that Alexander (1949) found mean plasma cholesterol levels of 176-197 mg/l 00 ml in two groups of Aleuts. 

In view of the small number of Eskimos examined in the present study no definite conclusion can be drawn from this limited material. These preliminary investigations indicate, however, that while some Eskimos, such as the Nunamiuts, may have very high cholesterol intakes, the average figures for dietary cholesterol and fat for the four Eskimo groups examined are comparable to those of the average American man; their blood cholesterol levels are the same, while the Sf 12-20 lipoproteins (Gofman fraction) were lower in concentration than Whites of corresponding age. If it were convincingly demonstrated that the Eskimos in reality have a lower incidence of cardiovascular disease than Whites, it would appear that these findings support Gofman's postulates that the high concentration of the cholesterol-bearing protein molecules are associated with atheroclerosis. 

It should be noted, however, that very little exact information is available regarding the occurrence of arteriosclerosis in Eskimos. None of the 16 Eskimos analyzed here showed any evidence of arteriosclerosis by clinical or roentgenological examination, and cardiovascular disease was extremely rare among the large number of Eskimo patients examined by the author during a two-year period in Alaska. Similarly, Dr. Paul Haggland, who has operated on a large number of Eskimos in Alaska during the last 15 years, has never seen arteriosclerosis or atherosclerosis in Eskimos (personal communications). He had the occasion to perform autopsy on one female and two male Eskimos, aged 60-65 years, and found no arteriosclerosis. Dr. Earl Albrecht, Territory Commissioner of Health, states that arteriosclerosis is rare in Eskimos, based on clinical evidence (personal communications). 

Bertelsen (1940) is, on the other hand, of the opinion that arteriosclerosis is fairly common in Greenland, particularly if one considers the average span of life for the Greenland Eskimos. Hoygaard (1941) writes with regard to the Angmagssalik Eskimos, Southeast Greenland, that "arteriosclerosis was frequently found even in persons below 40". 

Brown (1951) states with regard to the Southampton Island Eskimos and the Igloolik Eskimos: "We have found well-marked general arteriosclerosis and also coronary heart disease proved by electrocardiogram and, in one case, by post mortem. Some of the cases of coronary heart disease were in congestive failure." 

During our study of the patho-physiology of the Alaskan Eskimos from 1950 to 1952, x-rays were taken of the chest and extremities of 84 Eskimos, using a portable x-ray apparatus. All chest x-rays were taken at a distance of 180 cm; all x-rays of the limbs (left arm and left leg) were taken at a distance of 90 cm. Professor Johan Torgersen, Institute of Anatomy, Oslo University, has very kindly examined all these roentgenograms, with a particular reference to possible roentgenological evidence of arteriosclerosis and other cardiovascular abnormalities. He finds, as a typical feature of all roentgenograms examined, that the bone structure in the Eskimo is unusually massive with sharply defined, well-calcified bone lamellae. The muscle attachments are as a rule very large. The occurrence of arthritis deformans is no less frequent in these Eskimos than in Whites of similar age (:5 cases in 84 Eskimos, 51 males and 33 females, with an average age of 28 years). Four Eskimo subjects at Barter Island had cartilaginous exostoses on the tibia (fig. 2). 

From this material (see Table 5) it appears that the occurrence of roentgenological evidence of arteriosclerosis in these Eskimos is neither more nor less than what one would expect to find in Whites of similar age groups. Out of 9 Eskimos over 47 years of age, roentgenological evidence of atherosclerosis of the arch of the aorta was detected in 3 cases, 2 males and 1 female. Of the entire material one Eskimo showed calcium deposits in the arteries (see fig. 1). In one 60-year old Eskimo woman with a blood pressurc of 200/80, thcre was slight enlargemcnt of the left ventricle of the heart. It is thus evident that further studies are necessary in order to settle the question of arteriosclerosis in the Eskimo and the relation between dietary cholesterol, serum cholesterol levels and cardiovascular disease ill these people.

5. Summary and Conclusions. 

The cholesterol content of some common Eskimo foods has been determined and the serum cholesterol level as well as the serum concentration of Sf 12-20 lipoproteins in 16 healthy Alaskan Eskimos are reported. On the basis of these preliminary data it appears that some Eskimos have high cholesterol intakes compared with healthy American men, but that their blood cholesterol levels are the same. On the other hand, the Sf 12-20 lipoproteins in Eskimos are lower in concentration than in Whites of corresponding age. From the available evidence it appears that the incidence of cardiovascular disease among the Alaskan Eskimos may be lower than in whites. A more complete analysis of this problem is in progress.

A notable early example of this enduring controversy was “Keys versus Pickering”. The venue was the World Health Organization, and the year was 1955. There and then, Ancel Keys put forward his ideas expecting to be accepted on the spot, but he was challenged by Sir George Pickering, who according to witnesses said, “Yes, and Professor Keys would you be kind enough to cite for us the principle piece of evidence that you think supports this diet-heart theory of yours?” Keys’s evidence, at that time, was not convincing and his hypothesis was not accepted, which drove him to build the evidence that would allow him to prove his point.

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Health revolutionary: the life and work of Ancel Keys, (Documenting Public Health Leadership project of the Associations of Schools of Public Health and the Health Resources and Services Administration), DVD. Minneapolis, MN: University of Minnesota Schoool of Public Health, 2002

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"The pivotal moment in Keys life -- Keys got up from being knocked around and said 'I'll show those guys'...and he designed the Seven Countries study." - Nina Teicholz - TBFS - Page 36

The next year an article by Yerushalmy and Hilleboe appeared in what was a direct, and for Keys, painful sequel to the Geneva meeting. We learn from their footnote that: “The authors became interested in this question (diet vs. national mortality data) during a meeting of a WHO study group on atherosclerosis and ischemic heart disease in Geneva, Switzerland, November 1955. At that meeting statements were made about the association between heart disease and mortality and fat in the diet. As it later developed, these were based on a few selected countries and were of questionable validity. On their return to the United States, the authors reviewed the available data carefully, and the results indicated that the subject required further study.”

I recall well the reaction in Minnesota and in epidemiological circles to this article and the challenge it represented for proponents of the diet-heart idea. The article seemed to magnetize the pre-existing polar elements of the scientific community: the lines of force were drawn. Meanwhile, proponents were already reviewing data from several North American cohort studies showing the short-term predictive relationship of serum cholesterol level in health to risk of subsequent coronary events. Moreover, several investigators were involved in feeding experiments of the effects of fatty acid composition of diet on serum cholesterol level. Keys, meanwhile, had made new comparisons of diet and blood lipids among casual samples of men in South Africa and Japan, to test the relation in contrasting populations.

The tone of the Yerushalmy-Hilleboe “methodologic note” was authoritative, pedantic, and patronizing, beginning with: “The evidence which has been presented for the existence of a relationship between diet and heart disease, however, is, for the most part, derived from indirect methods of study. In these indirect methods the primary unit of observation is the group; in the direct method the primary unit of observation is the individual. . . .It is well known that the indirect method merely suggests that there is an association between the characteristics studied and mortality rates and, further, that no matter how plausible such an association may appear, it is not in itself proof of a cause-effect relationship.”

The authors go on to editorialize and scold the naïve: “The quotation and repetition of the suggestive association soon creates the impression that the relationship is truly valid, and ultimately it acquires status as a supporting link in a chain of presumed proof.” After admitting, however, that such an indirect method of study may be valuable, they again wax pedantic: “unfortunately, however, if you superficially accept and do not properly augment it, the indirect method has many weaknesses. The most serious is the fact that the apparent association often proves to be the result of non-pertinent extraneous factors. Therefore, it is always necessary to probe further, to go beyond the simple, apparent association and to investigate related variables.”

Dietary Fat Recommendations

1957:

• 25-30% of calories from total fat.

• “The possibility remains that the kind, rather than the amount of fat in the diet is responsible for atherosclerosis.”

Ancel Keys was alert to the idea that sugar might be an alternative dietary explanation to his own as a cause of heart disease. From the late 1950s to the early 1970s, he held an ongoing debate in the scientific literature with John Yudkin, a professor of physiology at Queen Elizabeth College, London University, who at the time was the man behind the sugar hypothesis. "Keys was very opposed to the sugar idea," Daan Kromhout recalled in an interview, though he could not say why. Philosophers of science would say that the job of a scientist is to be as skeptical as possible about his or her own ideas, but Keys was evidently just the opposite. "He was so convinced that fatty acids were the thing in relation ot atheroschlerosis, he saw everything from that perspective," says Kromhout. "He was a very driven person and had his own point of view." About the views of others, Keys could be aggressively disaparing: Yudkin's idea that sugar causes heart disease is a "mountain of nonsense," he concluded at the end of a nine-page criticque in Artherosclerosis. "Yudkin and his commercial backers were not deterred by the facts; they continue to sing the same discredited tune," he wrote later.

Keys specifically defended his Seven Countries study from the idea that sugar might explain some of the mortality differences he observed. 

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Nina Teicholz - TBFS - page 42