The 6 and 7 Country Study vs. the PURE Study

Hey y'all! Ancel Keys came up with the Diet Heart Hypothesis which led to the Dietary Guidelines. He did a 6 and 7 Country study that showed an increase in heart disease risk with increased fat intake. However, his 6 country study had 16 other countries that he left out. Why? It didn't match his hypothesis. Also, all of these studies are Pillar 1 evidence. That don't prove anything, but they can show a connection between things. (See a previous video to learn more about Pillars of Evidence)