Proving preventability

SPH and the birth of cardiovascular epidemiology.

Henry Blackburn tells the story of giving a talk in Finland in 1976 when the legendary British cardiologist Sir John McMichael was in the audience. At the end of Blackburn’s presentation, McMichael stood up and said, “Ladies and gentlemen, what you just heard this morning is entertainment. It has nothing to do with science.”

Blackburn, now SPH professor emeritus, had given a straightforward, data-filled report on the Seven Countries Study among cultures differing in traditional diets, one of the early forays into cardiovascular epidemiology conceived at the University of Minnesota.

“Basically, some people, such as McMicheal, were prejudiced against epidemiologic research and statistical methods,” says Blackburn. “The influence of diet and cholesterol in heart disease was also considered an ‘American’ idea and largely dismissed.”

What the body wants

Ancel Keys, left, and Henry Blackburn in Italy, circa the 1960s, for the Seven Countries Study.

Blackburn is among the few remaining principal investigators of the Seven Countries Study team that focused on the relation of heart attacks to the eating and activity patterns in contrasting populations of men in strenuous occupations like farming, fishing, and logging in the United States, Finland, the Netherlands, and Japan, Greece, Italy, and Yugoslavia.

The study, which began in 1958 and is now working on 50-year follow-up data, was the first to compare cardiovascular disease (CVD) rates across cultures and to follow subjects indefinitely. Its findings helped set today’s standards for healthy foods and lifestyles. The populations with the lowest rates of heart disease ate traditional diets with low saturated fat content, yet with varied amounts of total fat intake. They used meat as a condiment only, and focused on fish, legumes, vegetable oils, whole grains, fruits and vegetables, and wine with meals.

“There are whole cultures that eat very well, yet don’t have heart attacks,” says Blackburn. “The basic contribution of the Seven Countries Study is that CVD doesn’t need to exist. Most human beings are susceptible to it, but it’s largely preventable. High rates of heart attack in the population are about lifestyle and behaviors, not DNA.”

Getting it all down

Since retiring in 1995, Blackburn has devoted much of his time to writing and compiling a comprehensive archive and history of CVD epidemiology and preventive cardiology. His own and others’ documents, abstracts of early studies, oral histories of pioneering researchers, photos, videos, and audio clips are available on a wideranging website.

As a key player in establishing CVD epidemiology, Blackburn brings eyewitness accounts of the colorful and seminal Seven Countries Study, when researchers wandered the back roads of Croatia and rode ferries to island villages in Japan to explore the cultural origins of heart disease.

Field foundations

Blackburn had just finished his internal medicine residency in 1957 when University of Minnesota physiologist Ancel Keys offered him a job in his lab. Still considered a bit of an outlier in the medical community at the time, Keys had developed K-rations for WWII troops and conducted vital studies to discern how to safely begin re-feeding starved people after the war. He would go on to popularize the Mediterranean diet, make “cholesterol” part of our everyday vocabulary, and appear on the cover of Time magazine. Blackburn jumped at the chance to work with him.

From the late 1940s, Keys was beginning to recognize that heart disease was becoming epidemic in America. At the same time, he was hearing rumors that heart attacks were rare in certain countries, like Italy. So, with his chemist wife, Margaret, Keys began visiting those places and returned from each trip increasingly convinced of a tie between how populations lived and their rate of heart disease. Wanting to test his hypothesis in a systematic way, he conceived of the Seven Countries Study and enlisted Blackburn to create measures to use in the field.

Along with developing standardized patient history forms, Blackburn’s early assignment was to design the Minnesota Code, an objective classification system for electrocardiograms. That code and an advanced system designed by a colleague, the Novacode, remain the standards for all population-based CVD studies and prevention trials.

Path to a new discipline

As critical as the Seven Countries Study was to the founding of cardiovascular epidemiology, Blackburn’s current history project gives ample coverage to other endeavors and advances, such as the U.S. Public Health Service’s iconic Framingham Heart Study, begun in 1948 and still running. He honors the observant physicians of the past who started down the epidemiology road. Among them is Cornelis de Langen who, while stationed in the Dutch East Indies in 1914, noticed and reported on the absence of blood vessel disease among the Javanese and related it to their plant-based diet.

Blackburn began this project because his students had “a few deficiencies in the history of their field,” and because so many former household names, like the once well-known cardiologist Paul Dudley White, are being forgotten. “And no one under 60 has even heard of Ancel Keys,” he says.

Blackburn finds great satisfaction in the contributions of the University of Minnesota and the School of Public Health and Medical School. “The University was the earliest center of CVD epidemiology and prevention research and the first to recognize powerful social and cultural influences on the heart disease epidemic,” he says. “Minnesota work has had tremendous impact not only on science and medicine and the ultimate preventability of heart attacks, but also on the wider marketplace and how we as a people live and eat.”