Does it make sense that the foods people have eaten for millennia — meat, milk, eggs butter — should suddenly become enemies of public health? Plenty of scientists 50 years ago thought so.

“The Big Fat Surprise” Part II. Yesterday: An interview with author Nina Teicholz, noting that the decades-long claim that foods with fat are unhealthy has little basis in science. Today: How sound science and common sense got stampeded in an effort to address an epidemic of heart disease back in the 1960s.

It was almost 300 years ago that the French philosopher Voltaire declared that, “Common sense is not so common.”

Commentary:  The Big Fat Surprise: Part IIOf course, he was speaking French, so it would have sounded quite different, but a more recent development proves his point: Without anything remotely resembling the kind of rigorous scientific verification we demand these days, a handful of researchers in the 1960s managed to alter the eating habits, the dietary recommendations and the health status of the entire nation — for the worse.

All by twisting what too many “experts” believed at the time was rock-solid common sense. Here’s how it all happened, as condensed from Nina Teicholz’s detailed research and compelling prose.

As the postwar years progressed through the late 1940s and 1950s, much was right with the country. Although so much of Europe and Asia lay in ruins following World War II, the American economy was humming, jobs were plentiful, suburbs were exploding and freeways were spreading across the countryside to service our prosperous, mobile economy.

It was all good, except for an alarming rise in heart attacks. For two decades, heart disease, which had been relatively unknown in the 19th century, was rapidly becoming epidemic. By 1955, when President Eisenhower famously suffered a heart attack in the White House, annual mortality from heart disease had peaked at more than 425 deaths per 100,000 people.

Something had to be done, and along came a charismatic, self-promoting researcher named Ancel Keys, who came to what seemed like a logical conclusion. Keys observed that while well-nourished Americans were dropping dead from killer heart attacks, war-ravaged countries in Europe, where meat, milk and eggs were scarce, were seeing rates of cardiovascular disease declining significantly. Keys reasoned that high-fat foods that had high levels of saturated fat and cholesterol, were responsible for clogging the arteries of American businessmen, and he proceeded to sample diets and disease rates across a number of European countries.

His landmark — and now infamous — Seven Countries study determined that southern Italy’s “Mediterranean diet,” with olive oil and pasta replacing butter and meat, was the ideal choice to combat heart disease. The notion that foods low in animal fat were protective, and that the saturated fat and cholesterol found primarily in animal foods were bad news soon became gospel.

Forget the traditional dietary wisdom that focused on choosing “nutrient-dense” foods, which provided protein, vitamins and minerals. Postwar America no longer had to worry about undernutrition; our problem was overconsumption of steak and burgers, the newly anointed experts declared, foods that were deemed too “rich,” too high in fat and loaded with too much cholesterol to continue as the central components of our diets.

The cholesterol conundrum

Unfortunately, Keys’ study was riddled with flaws. He cherry-picked data (and countries), and like all dietary studies, his failed to account for any number of potentially confounding variables. Yet his aggressive promotion of what seemed like sensible advice convinced Sen. George McGovern, whose Senate committee fashioned a report echoing Keys’ claims, a report that soon became the template for USDA’s first Dietary Guidelines for Americans.

You can guess what it said: Cut back on saturated fat and cholesterol, which meant eat less red meat, and switch instead to plant-based foods, which in reality meant eating lots more carbohydrates, and not the whole-grain foods nutritionists like to promote, but processed and fast-foods loaded with sugar and sweeteners to replace the “bad” calories from fat.

Soon afterwards, the American Heart Association, the most influential organization involved in fighting the growing problem of cardiovascular disease, became staunch advocates of the low-fat diet. At the prestigious National Institutes of Health a new group was formed called the National Cholesterol Education Program, which was tasked with convincing Americans to lower their cholesterol levels by eating food with less cholesterol in them.

The reality that the human body manufactures cholesterol — a vital component of nervous system tissues — whether or not we are ingesting it in our daily meals did not seem to make a difference. The initiatives launched to reverse the alarming levels of heart disease was nothing less than a full-on crusade, and it swept up many a skeptical scientist in the fervor of reversing America’s No. 1 Public Health Enemy.

By the 1980s, the medical establishment, public health officials and the national media were all united in spreading what was a powerful message, one particularly focused on housewives: If you don’t want your husband to drop dead from a heart attack, stop buying so much beef — even though he loves it — and switch to pasta, fish or poultry. It got so bad that a TIME magazine cover featured “The Bad News about Cholesterol,” with fried eggs and bacon arranged in the opposite of the iconic smiley face pose.

And it worked. The statistics that any meat industry veteran can recite practically from memory showed that beef consumption began a serious slide around the mid-1970s and didn’t stop for another 30 years. Even worse, the notion that the saturated fat in red meat, whole milk, butter and eggs was bad news in terms of cardiovascular health became so solidified that even today, you’d be hard-pressed to find anyone who truly believes that eating animal foods are perfectly healthy. Even devoted carnivores adopt an “I don’t really care” attitude, and convince themselves they’ll beat the odds they stubbornly believe will likely result in premature death for plenty of otherwise healthy meat-eaters.

Just not them.

Despite a lack of solid science, and despite eons of human nutritional history — indeed, the very physiology we have all inherited evolved on a diet of wild game — the majority of people who consume animal foods regularly do so with at least a twinge of guilt.

When, in fact, we should embrace meat, dairy and eggs, as humanity has always done. Because they’re nutritious, healthy, natural and perfectly suited to support growth, development and lifelong well-being.

The path toward reversing the negativity that clings to animal foods (and thus animal agriculture) begins by going back in time to understand how and why the “fat is bad” message first emerged.

The best way to do that is to read “The Big Fat Surprise.” Pick a chapter, any chapter, and it will provide enough material to fuel a week’s worth of enlightenment.

Tomorrow: Summarizing Teicholz’s analysis of what the science actually says about what foods we should eat, and what dietary choices are best-suited for lifelong strength and health.

The opinions expressed in this commentary are solely those of Dan Murphy, a veteran food-industry journalist and commentator.