Fat or Fiction?

Fat or Fiction?

The Misleading Statistics and Debate Behind the Lipid Hypothesis

What is the Lipid Hypothesis?

The lipid hypothesis is the theory that high cholesterol intake, especially that of LDL, leads to increased risk of atherosclerosis and cardiovascular disease. (1)

How did the Lipid Hypothesis Come to Be?

During the 20th century, there was a concern in an evolving cardiovascular disease(CVD) related death epidemic. In light of this Ancel Keys underwent a study in relation to the lipid hypothesis to investigate a possible correlation between dietary habits and CVD. (2)

The Seven Countries Study

Out of 23 countries observed, 16 were excluded. Only 7 were considered.

In 1955, Keys presented his findings at a conference in Geneva and was met with criticism. In response to this, he began an elaborate study across several different countries to observe the heart attack risk of men in relation to their culture and their diet, particularily the relative proportion of fat. (2)

Statistical Misuse

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Using data from only seven countries strengthened the hypothesis.

Using data from all 22 countries would have produced a weaker correlation.

Issues and Lasting Effects

Statistical misuse caused the mistrust for heavy discourse in the medical sphere for over 60 years (3).

Finally, in 2023, the World Heart Association confirmed that high LDL lead to a higher risk of CVD after much additional research. The stigma and misinformation around this could have been greatly avoided given the correct framing of data.(3)

Citations1.Association, N. L. (n.d.). The lipid hypothesis. National Lipid Association Online. https://www.lipid.org/lipid-spin/summer-2022/lipid-hypothesis 2. Wikimedia Foundation. (2024, November 17). Lipid hypothesis. Wikipedia. https://en.wikipedia.org/wiki/Lipid_hypothesis 3. Newport, M. T., & Dayrit, F. M. (2024, May 11). The lipid-heart hypothesis and the keys equation defined the dietary guidelines but ignored the impact of trans-fat and high linoleic acid consumption. Nutrients. https://pmc.ncbi.nlm.nih.gov/articles/PMC11123895/

What is LDL?

Low-density lipoprotein (LDL) is a combination of a lipid and a protein that is often called the "bad" cholesterol, in opposition to HDL which is often called "good" cholesterol. (3)

Publication Bias

The Lipid Hypothesis was guilty of Publication Bias.

Key's used only studies that supported his initial hypothesis and omitted ones that did not. This created an illusory bias and dimished other possibly important factors to heart healthy dietary needs (3).

A 2019 meta-analysis found that 40-60% of published studies may be affected by publication bias across various disciplines. Although it may be tempting for researchers to publish only positive results, it leads to skewed evidence, poor policy decisions, and misleading public health recommendations (2).