The answer is cholesterol.
Cholesterol is a fat-like substance found only in the animal products. It is produced by the animal. About 75% of the cholesterol in your body is produced by the liver and remaining comes from the food you eat. Human body needs some cholesterol to build cell walls and produce some hormones. Excess of cholesterol is bad for our health. There are two main types of cholesterol, high-density lipoprotein (HDL) and low-density lipoprotein (LDL). HDL is 'good' cholesterol. It helps to remove cholesterol from the arteries and send back to the liver for disposal.