Cholesterol esters are a dietary lipid, which derived from cholesterol. Cholesterol esters are formed when the body produces enzymes to produce a metabolic reaction with the cholesterol itself. The ester bond is formed between the carboxylate group of a fatty acid and the hydroxyl group of cholesterol. Cholesterol esters are largely spread in body fluids of animals (plasma lipoproteins) and may be also found in vessel walls as fatty streaks in atherosclerosis. Cholesterol esters have a lower solubility in water due to their increased hydrophobicity.