Some doctors assume that the cholesterol in bile is a waste product – mere excess cholesterol to be excreted, but that makes no sense in view of the fact that the vast majority is reabsorbed, especially with our low fiber diets.
No – cholesterol is a vital lipid component of the emulsion that forms when bile, containing water, lipids and emulsifiers, is mixed with water and optimally additional dietary lipids by peristalsis – the lipid component of bile being especially useful when the meal is too low in fat. With cholesterol and bile, fat soluble substances can form weak emulsions in water and at least be inefficiently absorbed. This beats the scenario of fat soluble nutrients floating on the surface of the water, being excluded from the lower surface and the side surfaces of the intestine, and virtually never contacting the upper surface of the intestine for absorption. What a waste of valuable fat soluble nutrients, of which there are so many besides vitamins A, D, E, and K.
A quality mayonnaise-like emulsion allows the fat soluble substances good access to receptors on the bottom and sides of the intestinal walls and with vigorous mixing, occasionally on the top surface as well.