The Seven Countries Study: Finland

Northern Europe: Why Finland?

Forty years ago Martti Karvonen and Ancel Keys were convinced that Finland held a key to understanding mass atherosclerosis. They were quite right.

Here was a peaceful, rural land of hard working farmers and loggers, having traditions of close family ties and rugged independence, and with singular freedom from the stresses of Western industrial society. Yet, fatty artery disease was rampant.

Heart attacks, strokes, and claudication were well-known phenomena prior to World War II, but not epidemic until the long privations of wartime Finland were relieved.

In the countryside, it was essential that men eat calorie-dense foods. One could hardly cut trees, strip bark, pile logs, or till stony fields and bogs during a short growing season, all under inclement conditions, by “chewing one’s cud” or eating sprout sandwiches.

Loggers’ lunches, even today, are things of wonder, unsurpassed in caloric density: Large hunks of meat are suspended in congealed fat, enveloped in a dark bread loaf fully permeated by fat. The whole – at 250 grams of fat and well over 2,000 calories – is packaged in aluminum foil and tied with a ribbon. This hefty fare is preceded by a breakfast of fish soup, containing fifty percent butter fat calories and several grams of salt. The evening meal provides the rest of the 6,000 calories the logger needs to work outdoors all day.

Finland provides the clues, the tests, and the strongest arguments that the major socio-cultural influence on heart attacks and mass atherosclerosis is a diet of highly-saturated fatty acids from milk and meat fats.

Finland provides the primal ecologic evidence for the dietary cause and prevention of mass fatty artery diseases. East Finland departs from the regression line on the high side, that is, it has an even higher rate of coronary heart disease than expected from the overall Seven Countries population correlation between diet, blood cholesterol level and coronary heart disease.

In contrast, the West Finns have less coronary heart disease than expected from their average cholesterol level. There may be differences, as claimed by Finnish pathologists, in the internal caliber of the middle muscular layer of coronary vessels in the East Finns. Whether this, if true, is due to exposure to atherogenic lipids or represents the difference between the Ugrian origins of East Finns versus the Scandinavian origins of West Finns, remains at issue.

On the other hand, if oxidized low density lipoprotein is a major factor in its pathogenicity, then the East Finns’ coronary heart disease level is compatible also with the paucity of anti-oxidants and trace minerals in their foods and diet. Vitamins A, C, and E are consumed in relatively small quantities. Moreover, the soil of East Finland lacks selenium, so that even the few fruits and vegetables the Finns grow and eat are deficient in anti-oxidants.

Moreover, the Finns have high levels of iron, an oxidizing agent, in both their diet and blood serum.

Therefore, the individual correlations within Finland, and the regional differences for ecologic analysis, still provide a rich opportunity for testing major hypotheses about atherogenesis and thrombogenesis.

The relative and absolute intakes of omega-3 and omega-6 fatty acids also fit hypotheses about the roles of hypercoagulability and platelet function in atherosclerosis and hypertension. Moreover, physical activity shows a U-shaped distribution, with higher rates of cardiovascular disease in those Finns who are little active as well as at the other end among those engaged in heavily active occupations.

Finland provides the classic example of the importance of the mass determinants of population rates, over and above the individual’s risk of disease. For example, the high general level of occupational and leisure time physical activity, and high levels of measured physical fitness in Finland, fail to prevent the ravages of high population levels of blood cholesterol. The latter becomes the necessary cause of mass atherosclerosis.

Though the picture in Finland confirms the major causal hypothesis about the role of dietary saturated fatty acids, a basic issue remains, as exposed in a practical dietary experiment completed some years ago. Can the picture be changed? East Finns were placed on an Italian diet and Italian farmers on a Finnish diet. As in the black and white prisoners that Keys and John Brock of Capetown studied in Southern Africa forty years before; the groups rapidly approached the blood lipid characteristics of those in the adopted eating pattern.

These findings recall the admonition of Jeremy Swan, distinguished clinical scientist from Los Angeles, who once said to me: “It’s ridiculous, Henry, to think that a process as complex as atherosclerosis can be attributed to or changed by such a simplistic matter as habitual diet!”

I have great respect for such people who explore “the baroque beauty of biology” in its infinite perplexities. But I must admit to greater admiration for the distinguished clinician or scientist who sees the whole picture, not just its complex parts, and who realizes the importance of simple ideas and even of “simple research” on those ideas. For example, the terrible biologic complexity of metaplasia and carcinoma in the bronchi would, of course, largely disappear with one simple (?) public health measure – cessation of cigarette smoking.

The evidence is also strong that fatty artery diseases disappear, or fail to appear, in populations having habitual diets that produce population cholesterol averages less than 190 mg/dl.

At any rate, the “natural experiment” of Finland was, and is, a fertile field for research by Keys and company in the Seven Countries Study.

East Finland, Second Round, September, 1964

The five-year follow-up in Finland in 1964, started with the East Finnish cohort in Ilomantsi, a country village serving a large farming and logging area along the Russian frontier.

The Finnish survey team worked effectively amidst the calm beauty of that land. The participants were hard-working and seemingly happy people, close to the earth, laboring in the forest and fields, and on the endless glacial lakes. They came to our border guard survey station from many kilometers around.

For this survey, the local investigators, led by Karvonen, planned an international conference on methods for assessing physical activity and fitness in populations.

Henry Taylor from our laboratory played a major role in organizing the Minnesota contributions, and in the course of the conference paid his first visit to the Seven Countries Study international surveys.

Once the conference and social activities surrounding it were over, the field team turned to its survey task with enthusiasm. The border patrol station, which housed the guards and their activities at the Russian frontier, was released to the examination team for the several weeks required to complete the survey of some 800 East Finnish men.

There was an especially elaborate protocol for the examinations in 1964, with add-ons of psychosocial questionnaires and psychomotor testing by Alan Barry and his group from Lankenau Hospital, and of bicycle ergometry with computerized exercise and standard rest electrocardiography. Rautaharju, Hermann Wolf, and the Dalhousie team also made recordings of heart sounds, chest wall excursions, and pulse wave velocity, the beginnings of what we anticipated would be routine high-tech evaluations for epidemiological field studies.

For some years at that time, I headed a U.S. Public Health Service Heart Disease Control Program Sub-committee on exercise electrocardiography and physiologic methods. We were full of grand ideas about how to get objective, continuous measurements in whole populations having different risk of cardiovascular disease. From experience in the U.S. Railway Study and similar undertakings, we should have been less sanguine that the high-tech approach would soon produce data in a usable format. Thirty years later, however, the methods sewn then are finally bearing fruit in the activities of Rautaharju’s Epicore group.

The Finnish international survey team took to its task with vigor. The local field workers had prepared well for the survey. Led by Karvonen and Orma, they were resourceful in dealing with the unending series of unexpected happenings: power failures, equipment failures, and people failures. The Finns, a serious lot generally, have a streak of sardonic humor, which makes collaboration in field activities most pleasant. Moreover, they always have an eye toward the “R and R” time that must come in every field operation. Five or six twelve-hour days of a steady load of fifty to seventy examinees a day was about the limit before a break. Three weeks of this grind, and a significant hiatus is needed so that staff can return, at least briefly, to their homes and offices.

A Country Sauna

Pirkko (now Siltonen), our chief survey technician in 1964, was the Finnish “den mother,” vigorous, competent, cheerful, and gregarious. Though dead serious about the survey work, she always had mischief in her eye. It was Pirkko who saw to it that the initial interviewers established rapport with the wonderful Karelian men, some of whom had ridden bicycles many kilometers to the station for their examination.

These interviewers were able to seek out, diplomatically, the information that Pirkko wanted for the “social good” of our team. She sought farmers and loggers living in the countryside who, in our brief contact with them, had shown a good feeling toward the study and the team, and who would reveal what kind of country sauna existed on their property.

Eventually, we decided that this question was also appropriate to the formal part of the activity questionnaire, because the sauna is such an essential part of Finnish lifestyle. At any rate, in time, Pirkko had the desired information in hand.

The first weeks’ examinations having gone on for seven days running, one of the interviewers came into our electrocardiographic station one morning dangling before our weary eyes an old-fashioned key – the key to an isolated wood sauna far off in the autumn landscape of Karelia. Plans were laid for a sauna party that very night.

When the medical part of the team arrived at the moonlit farm, led by Pirkko, we found a dramatic nighttime scene. Lanterns hung on boughs about the sauna, a cheery fire blazing inside, with everywhere the lovely fragrance of wood smoke – birch and pine. Wrapped in moss in a pail was a packet of leafy birch branches of uniform length and maturity, picked, we were told, in mid-June and carefully stored. Pirkko grasped them in her happy arms and plunged them into a bucket of cold lake water.

Soon we heard squeals and giggles from inside the sauna. According to custom, the women had arrived earlier, prepared the fire and were taking their sauna before the extreme temperatures had been reached. As the men disrobed in the nearby woods, the women poured out of the hot house, ran down the dock and plunged into the lake, splashing about with shrieks and laughter. Quickly climbing from the water, girded in towels, they rushed into the dark to change into warm clothes and start preparing our picnic meal.

Now it was time for the men to take the “real” sauna. The Finns wet themselves down while the visitors stayed dry, and we entered to face a searing blast of hot air beyond any previous experience. Visitors were encouraged to take the lower benches, but we chose the higher ones so as not to appear weak. There, eyes shut, breathing shallowly, we adapted gradually to the beauty and fragrance of the searing envelope.

All were silent at first, emitting only occasional grunts and sighs. Opening our eyes to peek through the subdued light, cardiologists and physiologists were reduced to the same parboiled, common denominator. Karvonen, our sauna-master, ordered us out after only ten minutes exposure, to sit quietly on a bench outside where we watched the distant silhouettes of the women around the camp fire.

Then the men returned to the torture for a second round, the temperature having soared another notch in our absence. In preparation for the ultimate initiation, the novitiates were again strongly encouraged to sit on the lower benches, then instructed on what would happen and how to behave. It turned out that the instruction was wholly inadequate to deal with the actual experience.

When a bucketful of water hit the bed of blistering rocks, it vaporized explosively, rising to the top of the sauna where our colleagues on the benches above held their breaths, immobile. Suddenly, the steam layer reached our level with an incomprehensibly scalding heat. One dared not breathe, sparing the lungs. After a first gasp we held our breaths as long as possible and expired as slowly as possible, until, after a few seconds, the worst was over. Then we broke into a profuse sweat.

Our leader extracted the leafy birch twigs from the water bucket, laid them momentarily on the sizzling rocks, and then proceeded to flagellate himself, and us, on the neck, back, shoulders, arms, buttocks, thighs, legs, and feet, bidding us do the same. Under the fragrant, stinging shock, every sensory ending is illuminated, firing at its maximal amplitude, creating an exquisite pain.

Then someone opened a beer and sprayed its contents on the sauna rocks, the hot, yeasty steam enveloping us until we could no longer stand it. We all burst simultaneously from the heat, ran down the dock, and plunged into the lake. There, the whole mass of tingling nerve endings was reactivated by the shock of the frigid water. Neurosensory endings stimulated so maximally cannot distinguish cold from hot, but can only respond with a fury of sensation.

I left the water quickly, feeling nauseated and faint from what must have been massive arteriolar constriction in the skin, plus a bradycardic dive reflex and major redistribution of blood volume.

After a few minutes of quiet sitting, an elevating calm invaded. Vitality crept back into our bodies. We toweled off gently, cooling down slowly. Beers were passed around, and, feeling ever more mellow, we dressed and gathered around the campfire for food and conversation.

We visitors were impressed, for life, with the trial by fire of this near-sacred Finnish ordeal!