Saturated Fat: What is the True Story? Part 1: Research and Questions

 

For decades the American public has been warned that eating saturated fat, the type found in meat and processed foods, can lead to heart disease.  Now there is a booming cottage industry peddling the argument that saturated fat is good for us. Unfortunately, for those who wish to believe this, the argument is invalid.

The relevant literature has already been summarized for us in some rather famous, if not infamous, systematic reviews. The very purpose of systematic reviews, and their quantitative counterpart, meta-analysis, is to help establish conclusions based not just on any one study, but the overall weight of evidence. Systematic reviews and meta-analyses about saturated fat and health outcomes are readily available.

There are only two reviews that suggest we consume more saturated fat. The first dates from 2010; the second from 2014. They differ in many details, but they effectively address the same basic issue. What did they find? Rates of heart disease were high, and almost exactly the same, at the high and low ends of the saturated fat intake range. The currently popular argument is that rates of heart disease did not go down when saturated fat intake went down; and therefore, saturated fat must be good for us.

These studies represent poor science. We could use exactly the same data, and just the same “logic,” to argue that rates of heart disease did not go down when saturated fat intake went up; and therefore, saturated fat must be bad for us (still).

The simple fact is that neither of these assertions is valid. If heart disease rates don’t change across the range of saturated fat being examined, all it does is raise additional questions. How much variation is there in saturated fat intake in the first place? If there isn’t much, it’s no surprise that outcomes affected by saturated fat don’t vary much either.  When saturated fat intake goes down, what is replacing it – and what is happening to the overall diet quality?