A Sign of Bad Science - Mistaking Correlation for Causation

The premise of the book, Good Calories, Bad Calories, is that most 20th century nutritional advice is based on "bad science." Science and food writer Gary Taubes, posits that "low fat" diets - en vogue in the latter half of the 20th century - is based on deeply flawed assumptions of data. In the first chapter of the book, he recounts how researchers of the day confused correlation with causation exacerbated by data cherry-picking. Although the concept of correlation is a simple concept, confusing correlation with causation trips up even the brightest minds with the best of intentions.

Here is a useful primer on the Fallacy of Correlation versus Causation

Bad Science

“In 1913, the Russian pathologist Nikolaj Anitschkow reported that he could induce atherosclerotic-type lesions in rabbits by feeding them olive oil and cholesterol. Rabbits, though, are herbivores and would never consume such high-cholesterol diets naturally.”

Rabbits developed the buildup of cholesterol in their tendons and connective tissues, suggesting it was a storage disease - meaning they had no way to metabolize. Despite this obvious flaw in methodology, the authors of the study concluded that high-fat diets caused a 'cholesterol disease of rabbits.'

Life Expectancy - 1900 versus 1950

Source: Our World in Data

In 1900, the average lifespan in the United States ranged from forty to fifty years. By 1950, lifespans had extended on average between sixty and seventy years. While infectious diseases were still (and still are) a major concern, extending lifespans revealed an entirely new set of healthcare challenges.

The first chapter reveals many more egregious errors. Heart disease was declared a major health issue in mid 20th century. Eisenhower's heart disease helped to catapult the disease to the forefront of America's concern. Yes, more Americans were in fact dying from heart attacks. However, there was something else at play. More Americans were dying from chronic diseases, as compared to contagious diseases like cholera and the flu, because they were living longer. Antibiotics and advances in public health extended the average lifespan by decades. However, when culling through mortality data, scientists did not connect the second order effects of living longer.

As I read through this chapter, I was reminded of the incipient nature of science and medicine. In the grand scheme of human existence, medicine & biology are still relatively novel fields. My other blog post on the state of medicine in the early 20th century touches on the infantile nature of American medicine in the early 19th and 20th centuries.

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