The demonization of dietary cholesterol can be traced back to the mid-20th century, largely due to evolving scientific understanding and public health policies. Here’s a brief overview of how and why this happened:

1. Early Research: In the early 1900s, scientists began to understand more about cholesterol and its role in the body. The link between cholesterol and heart disease started to emerge in the 1950s, particularly through the work of Ancel Keys and his landmark Seven Countries Study. This study suggested a strong correlation between saturated fat intake, cholesterol levels, and heart disease.
2. Simplification of Science: The relationship between dietary cholesterol, blood cholesterol, and heart disease was complex, but public health messages often simplified it to “cholesterol in food raises blood cholesterol and causes heart disease.” This led to the demonization of foods high in cholesterol.
3. Government Guidelines: In the 1960s and 1970s, based on the prevailing scientific understanding, governmental bodies in the United States and other countries started recommending that people reduce their intake of cholesterol and saturated fat to lower heart disease risk. This further entrenched the idea that dietary cholesterol was harmful.
4. Public Perception and Food Industry Response: The public health campaigns against cholesterol had a significant impact on public perception. The food industry responded by creating and marketing low-cholesterol and cholesterol-free products, reinforcing the idea that dietary cholesterol was bad.
5. Evolving Understanding: Over time, further research showed that the relationship between dietary cholesterol and blood cholesterol levels is not as straightforward as once thought. It became clear that saturated fat and trans fats have a more significant impact on blood cholesterol levels than dietary cholesterol itself. Also, individual responses to dietary cholesterol vary greatly.
6. Recent Dietary Guidelines: Recent guidelines, like the 2015-2020 Dietary Guidelines for Americans, have shifted away from strict limits on dietary cholesterol, focusing instead on overall dietary patterns. However, the long-standing message about cholesterol’s dangers has left a lasting impact on public consciousness.

In summary, the demonization of dietary cholesterol was the result of early scientific research linking cholesterol to heart disease, simplified public health messages, and reinforced by government guidelines and food industry marketing. However, as scientific understanding has evolved, the view of dietary cholesterol has become more nuanced, focusing on the importance of a balanced diet and the greater impact of other types of fats on heart health.