Butter Gets a Bad Rap

In the mid-20th century, Ancel Keys put forward the "lipid hypothesis"—the idea that eating saturated fat (found in abundance in butter, eggs, and meat) raises cholesterol and causes heart disease. His work became the foundation for decades of low-fat dietary advice, which pushed people away from traditional fats and straight into the arms of margarine and processed seed oils.

Here is the story of how a flawed theory reshaped the global diet.

The Great Heart Scare and the 1953 Curve

In the 1940s and 1950s, American men were suddenly dropping dead from heart attacks at an alarming rate. Even President Dwight Eisenhower had a heart attack in 1955, making the issue a national panic. Everyone wanted to know: *What is causing this?*

Ancel Keys, a charismatic and highly influential physiologist at the University of Minnesota, believed he had the definitive answer: dietary fat.

In 1953, Keys published a paper featuring a graph that showed a near-perfect link between the amount of fat people ate in six specific countries and their rates of heart disease. Countries like Japan ate very little fat and had low heart disease rates; countries like the United States ate a lot of fat and had high heart disease rates..

Keys' cherry-picked his data. He actually had access to statistics for 22 countries. When all 22 countries were plotted on the graph, the neat relationship completely vanished. For instance, countries like France and West Germany ate plenty of fat but had low rates of heart disease. By hiding the data that didn't fit his theory, Keys made a weak guess look like scientific absolute truth.

The Seven Countries Study

To prove his point on a grander scale, Keys launched the famous Seven Countries Study in 1958, tracking the diets and health of roughly 12,000 men.

Once again, critics point out that he chose his locations carefully—including places like Italy and Greece, where people ate a Mediterranean diet, while intentionally leaving out countries like Switzerland and France where people ate high-fat diets but remained perfectly healthy.

Because Keys was brilliant at politics and networking, he managed to get himself onto the nutrition committee of the American Heart Association (AHA). In 1961, the AHA issued its first-ever guidelines telling people to cut back on saturated fat.

The Rise of "Fake" Butter and Seed Oils

Once butter was labeled public enemy number one, food manufacturers rushed to fill the gap with cheap alternatives.

Margarine:

Made by chemically pumping hydrogen gas into liquid vegetable oils (a process called hydrogenation) to make them solid at room temperature. This unintentionally created **trans fats**, which we now know are far worse for human arteries than regular saturated fat ever was.

Industrial Seed Oils:

Oils made from corn, soybeans, safflower, and cottonseed were promoted as healthy, cholesterol-lowering alternatives. Because these oils are highly unstable, they require intense chemical refining, bleaching, and deodorizing just to look and smell edible

By the late 1970s, the US government issued its official Dietary Goals for the United States, cementing the low-fat, high-carbohydrate paradigm into school lunches, medical training, and grocery store aisles.

The Aftermath

As the public stopped eating butter and switched to highly processed seed oils and low-fat foods (which were usually packed with extra sugar to make up for the lost flavour), rates of obesity, type 2 diabetes, and metabolic chronic illness skyrocketed.

Decades later, independent researchers went back and re-examined Keys' original data, alongside massive buried clinical trials like the Minnesota Coronary Experiment (which Keys helped run but never fully published because the results didn't fit his narrative). 

The conclusion? 

While switching to seed oils did lower blood cholesterol, it did not reduce heart attacks or extend life.

Today, modern nutritional science has largely cleared natural, high-quality butter of its "villain" status, recognizing it as a nutrient-dense whole food, while heavily scrutinizing the highly processed industrial oils that replaced it.