Bile acid has a detergent action due to:

C i.e. Amphipathic nature of bile acids.Bile adds have detergent action on the lipids due to their amphipathic natureQ. They make the lipids soluble by forming micelles.Bile acids are synthesized from cholesterol and bile salts are sodium & potassium salts of bile acid.Bile salts have amphipathic natureQ. i.e. they have both hydrophilic and hydrophobic domains. Therefore they tend to form cylindrical disk called micelles, with the hydrophilic surface facing out and the hydrophobic surfaces facing in.Lipids collect within the micelles.The micelles play are impoant role in keeping lipids in solution & transpoing them to the brush border, where they absorb.