Have you ever seen studies claiming that dietary cholesterol and saturated fat have no correlation to heart disease?  Dr. Michael Greger explains how we’ve known since 1979 that cross-sectional population studies will unavoidably show a zero correlation between diet and heart disease because of the large differences between individual cholesterol levels.  Cross-sectional studies lack the statistical power to show a correlation, which is why the vast bulk of evidence linking heart disease to diet comes from metabolic ward and free living dietary change experiments.