Ischemic Heart Attacks: Disease of Civilization

Or, more precisely, disease of industrial civilization.

The scientific literature contains examples of cultures that don't suffer from the chronic non-communicable diseases that are so common in modern societies. Much of what I've read indicates that heart attacks are practically unique to cultures that have adopted industrial foodways and a modern lifestyle, being infrequent or entirely absent in those that have not.

I recently came across an incredible paper from 1964 in the American Journal of Cardiology, titled "Geographic Pathology of Myocardial Infarction", by lead author Dr. Kyu Taik Lee (Am. J. Cardiol. 13:30. 1964). This was published during a period of intense research into the cardiovascular health of non-industrial cultures, including Dr. George V. Mann's famous study of the Masai.

The first thing Lee and his colleagues did was collect autopsy statistics from San Francisco and Los Angeles hospitals. They analyzed the data by race, including categories for Caucasian-Americans (white), Japanese-Americans, Chinese-Americans, and Filipino-Americans. All races had a similar incidence of autopsy-proven myocardial infarction (MI = heart attack), including both silent (healed) and fatal MI. For comparison, they included a table with autopsy data from hospitals in Tokyo, South Japan and North Japan. I'm including the data from Tokyo in the graph because it's also an urban environment, but the finding was the same in all three regions. Here's what they found, by age group: The Japanese had a very low rate of MI compared to both Caucasian-Americans and Japanese-Americans. The rate of MI in Caucasian-Americans and Japanese-Americans did not differ significantly. Thus, location but not race determined the susceptibility to MI.

Next, the investigators collected autopsy data from hospitals in New Orleans, again divided by race. This time they exained Caucasian-Americans and African-Americans. Both groups had a very high rate of MI, as expected, although the African-Americans had a lower rate than Caucasian-Americans. They also collected data from autopsies in Nigeria and Uganda for comparison. Here are the data for men: And for women: Again, location but not race largely determined the incidence of MI. MI was extremely rare in the African autopsies. Here's what they had to say:

There was only 1 case of healed myocardial infarction among over 4,000 adult autopsies in the Uganda series, and only 2 cases of healed myocardial infarction among over 500 adult autopsies in the Nigerian series. In the New Orleans Negro series the occurrence rate was far greater in every sex and age group than in either one of the Negro series in East and West Africa.

Over 4,500 autopsies and not a single fatal MI. If this isn't worth studying, what is? These data should be part of first-year training in medicine and health programs.

To satisfy the skeptics, Lee and colleagues imported hundreds of hearts from consecutive autopsies in Albany (USA), Africa, Korea and Japan. They had an American pathologist analyze them side-by side to eliminate any diagnostic bias. Here's what they found:

In the African Negro series no infarct was found in any age group [out of 244 hearts, 39 over 60 years old]. In the Korean series there were only 2 cases of myocardial infarction [out of 106 hearts] and they were both women... In the Japanese series there were 8 cases of myocardial infarction in 259 hearts. All were men...

In the American sample, nearly 40% of the hearts of men and women over 60 showed signs of MI. The findings of the American pathologist confirmed the international autopsy data, showing that diagnostic bias did not contribute to the results significantly. They also took measurements of the thickness of the coronary artery wall, an index of atherosclerosis. They found that the Americans had the most atherosclerosis, but all cultures had some degree of it and there was overlap in the amount of atherosclerosis between samples. This led the investigators to state:

Myocardial infarction and coronary thrombosis are almost nonexistent in Uganda and Nigeria, and the amount of coronary arteriosclerosis is significantly less in Africans than in whites. However, in the two groups there was some overlapping in the degree of arteriosclerosis. No Africans had infarcts, but some had the same or a greater degree of coronary arteriosclerosis as a few whites who had myocardial infarctions. One explanation for this may be that some difference in clotting or clot-lysis mechanisms is present in the two groups. In a previous study, we showed that the incidence of thromboembolic phenomena in the pulmonary circulation [blood clots in the lungs] was low in East Africans as compared with Americans.

Now, the authors' conclusions:

These data strongly suggest that among the Orientals the environmental factor is playing a major role in the etiology of myocardial infarction and coronary thrombosis. If the genetic factor is an important one, those Orientals who moved to this country many years ago or who were born in this country should still maintain their low occurrence rate of myocardial infarction at least to some extent, and one would not expect to see similar occurrence rates of myocardial infarction in Orientals and whites as old as 50 to 59 years... As with the Orientals, this suggests that for Negroes in the United States environmental factors are more important than genetic factors in the etiology of myocardial infarction.

Africans in Africa and Japanese in Japan = low incidence of MI. Africans, Japanese and Caucasians in the US = high and similar incidence of MI. Genes only influence a person's susceptibility to MI when they live in an environment that promotes MI. Otherwise, genes are basically irrelevant.

What do the traditional diets and lifestyles of Japan and Africa have in common? Not much. Even within Nigeria, the diet varies from heavily starch-based (root vegetables, soaked/fermented non-gluten grains, beans, plantains) to mostly reliant on high-fat dairy and meat. In fact, I believe it's the wrong question to ask. A better question is "what do we eat/do in the US that traditional Japanese, Koreans, Chinese, Polynesians, Melanesians and Africans don't"? For starters, none of them rely on industrial vegetable oils, sugar and wheat to nearly the same extent as modern America. Their food is generally prepared at home using wholesome ingredients and traditional methods.

They probably get more exercise than Americans, even if it's only walking in Tokyo or domestic tasks for women in parts of Africa. Traditional Africans surely get more sunlight and thus more vitamin D. I can't imagine life is less stressful in Tokyo than in San Francisco or Los Angeles.

I really like this study, and I think these graphs should be disseminated as much as possible. I've prepared high-resolution versions in JPEG, Powerpoint and PDF formats. E-mail me (click on my profile for the link) if you would like a copy. Let me know which format(s) you want.

Cleave and Yudkin on Fats

Drs. T. L. Cleave (1906-1983) and John Yudkin (1910-1995) were two diet-health researchers who believed that refined carbohydrate-- and particularly refined sugar-- are behind many modern health problems. They made their case in the scientific journals, as well as in books aimed at the general public. They were also witheringly dismissive of the idea that animal fats could be behind the coronary heart disease epidemic of the 20th century. I'm going to post a few quotes of theirs that I'm particularly fond of, relating to this. I'll start off with a few oldies but goodies from T. L. Cleave's The Saccharine Disease, page 100:

Those who incriminate animal fats in raising the blood lipids and causing coronary disease would have us stop eating the fats that we have been eating from immemorial time, such as the fat found in meat and in the butter and cream derived from milk, and eat instead a whole lot of new oils, mainly expressed from vegetable seeds, many of which oils are alien to us.

From pages 100-101:

The keeping of flocks of sheep, herds of cattle, and other domestic animals, in order to provide a continuity of meat and milk, started with neolithic man many thousands of years before the Christian era... To these fats we are therefore well adapted, quite apart from man, as a hunter, being well acquainted with the fat of animals in evolutionary times far more remote than the neolithic ones.

From page 101:

Contrast with these ancient fats the new oils, mainly expressed from vegetable seeds. Not only are many of these seeds not a natural food for man (e.g., cotton seed and sunflower seed-- and incidentally the sunflower does not even come from the Old World, as we do in the British isles, but from the New), but also the oils expressed from many of them never existed in any quantity before the invention of the modern hydraulic press or the new solvent procedures, and consequently were scarcely eaten in this country before the introduction of margarine, circa 1916, during the First World War. Evolutionarily these oils make us not so much men as the equivalent of a flock of greenfinches, and the evolutionary incongruity is heightened by the fact that the coronary explosion amongst us, as will be seen later, came in since the introduction of just these oils at the period stated, though in margarine they are often saturated by a stream of hydrogen.

Now for a little John Yudkin. From "Dietary Factors in Arteriosclerosis: Sucrose" (Lipids 13(5):370. 1978):

In principle, it is very doubtful that one can in any way profoundly modify the diet of any species, including Homo sapiens, without introducing some hazard. The consumption of large quantities of PUFA [polyunsaturated fat] has been made possible only by the very recent development of sophisticated techniques of cultivating oilseeds, and extracting and refining vegetable oils. Before such techniques were available, these oils made only a small contribution to our diets, as they still do in the poorer countries. We cannot ignore the evidence that the large amounts widely recommended nowadays as a preventive of CHD can produce undesirable effects, such as increasing the risk of gallstones and possibly of carcinomatous changes in the skin. On the other hand, the reduction of the high amounts of sugar that we now consume is not known to be accompanied by any hazard.

Drs. T. L. Cleave and John Yudkin: making sense since 1936.