A medium-sized egg (about 60 grams) can contain up to 200 milligrams of cholesterol, against an estimated daily requirement of 300 milligrams. This substance is present with a rather low content (it represents 5% of the lipid fraction) in the yolk, which is rich in unsaturated fatty acids and lecithin, a compound able to decrease the absorption of cholesterol. It is also good to remember that it is the human organism itself that produces most of the cholesterol found in the blood, as a precursor to fundamental substances such as bile acids and steroid hormones, which otherwise could not be synthesised correctly.