There is ongoing debate about whether dietary saturated fat increases cholesterol levels. In reality, both sides of the argument contain some truth: some individuals can increase saturated fat intake without significant changes in cholesterol levels, while others experience substantial increases.
A review article by Bruce Griffin et al. published in Atherosclerosis describes the complexity of cholesterol and saturated fat metabolism. The authors emphasize that absorption of these nutrients can vary significantly among individuals and may change over time.
Bile plays a central role in dietary fat absorption. However, bile acids can be modified by gut bacteria, which can reduce their effectiveness in facilitating fat absorption. Dietary fat itself can also influence the composition and function of gut microbiota.
As the authors note:
The gut microbiota shares a bi-directional relationship with dietary fat, influencing fat absorption through bile salts while also being modified by dietary fat.
This relationship illustrates how diet can influence cholesterol levels not only directly through macronutrient intake but also indirectly through effects on digestion and absorption.
Individuals who adopt major dietary changes — such as ketogenic or paleo diets — should consider periodically measuring lipid levels to monitor changes in cholesterol, triglycerides, and insulin sensitivity.