The Great Cholesterol Myth summary

Human beings need cholesterol. In the body, this waxy substance aids the formation of cell membranes, is used to produce hormones like testosterone and estrogen, and even supports digestion.

So why does cholesterol get such bad press? Why do dietary pundits constantly tell us that it’s bad for our health?

To answer that question we need to revisit a nutritional controversy from the mid-twentieth century. 

The key player was a young biologist named Ancel Keys, who had just formulated a revolutionary new theory; he argued that too much fat in the diet raised cholesterol levels, ultimately leading to heart disease.

Before long, the theory caught on – and health bodies across the US were soon warning citizens to cut down on fat. There was just one problem, though: the theory relied on data that simply didn’t add up.

The key message here is: The demonization of cholesterol rests on outdated and bad science.

There were a number of problems with Keys’s research. First, let’s consider his famous Seven Countries Study, which showed that the nations that ate the most fat also experienced the most heart disease.

Sounds pretty clear-cut, right? Well, let’s look a little closer. Keys actually had access to data on 22 countries, not seven – and those he excluded from the study painted an entirely different picture.

For example, the inhabitants of two Greek islands, Crete and Corfu, consumed fat at almost exactly the same rate. According to Keys’s hypothesis, you might expect them to have similar levels of heart disease.

The thing is, they don’t. In Corfu, death from heart disease was a staggering 17 times higher than it was in Crete.

Clearly, something other than fat consumption was at play. But what?

Enter John Yudkin, a British doctor and nutritionist working at the University of London. Yudkin was skeptical of Keys’s findings, so he decided to carry out a similar study himself – but he made sure to include far more data than Keys had.

When Yudkin analyzed the numbers, he found that there was indeed a single dietary factor strongly associated with heart disease. But it wasn’t fat. It was sugar.

Unfortunately, the work of scientists like Yudkin was disregarded, and Keys’s attack on fat went mainstream. To the public, the defenders of fat seemed all too similar to the crooked scientists who’d spent years defending tobacco.