How do bile acids help the intestine absorb dietary fats?

Bile acids, which are steroid compounds derived from cholesterol, facilitate the absorption of dietary fats through two primary mechanisms: emulsification and the formation of micelles.123

• Emulsification: Bile acids act as detergents that break down large globules of dietary fat into smaller droplets. This process significantly increases the surface area of the fat, allowing digestive enzymes—specifically lipases—to break down triglycerides into monoglycerides and fatty acids more efficiently.14
• Micelle Formation: Because bile acids possess both hydrophobic (water-repelling) and hydrophilic (water-attracting) regions, they organize into structures called micelles. These micelles encapsulate fat components, including fatty acids, monoglycerides, cholesterol, and fat-soluble vitamins (A, D, E, and K), making them soluble in the watery environment of the small intestine.41

Once these micelles transport the lipids across the "unstirred" fluid layer to the intestinal cell membranes, the lipids are absorbed into the cells, and the bile acids are released to continue their role in the enterohepatic circulation.14