Cholesterol is a fatty substance found in every cell of the human body. It is normally produced by our liver and intestines but it can also be ingested from animal-derived foods. Cholesterol is found in animal fat, which is consumed directly, or indirectly, as ingredients in food. Our body needs cholesterol, but not in a huge amount.
Cholesterol is an important building block for the nerves, brain cells, and certain hormones. This makes it indispensable for the human body. It is one of the factors involved in allowing the nerve cells (neurons) to communicate with each other and exchange electrical signals.
Cholesterol makes digestive bile acid in the intestine. Synthesis of bile acid is a major route of cholesterol metabolism in most species other than humans. The body produces about 800 mg of cholesterol per day and about half of that is used for bile acid synthesis, which results in 400–600 mg daily. Human adults secrete between 12-18 g of bile acid into the intestine each day, mostly after meals.
There is a close connection in the body between Vitamin D and cholesterol. Most often the human body gets vitamin D from sunlight. Cholesterol is involved in the process of synthesizing vitamin D from sunlight, and without cholesterol this would be impossible.
Cholesterol also enables the body to make certain hormones. For example, steroid hormones, which help control metabolism, inflammation, mineral levels, blood pressure, libido, and immune functions, are generally synthesized from cholesterol.
Cholesterol is divided into "good" HDL cholesterol and "bad" LDL cholesterol. HDL and LDL are actually the transporters of cholesterol in the blood, called lipoproteins.
HDL means “high-density lipoprotein” - this is the "good" cholesterol that helps keep cholesterol away from your arteries and remove any excess from arterial plaque, which may help to prevent heart disease.
LDL is for “low-density-lipoprotein” – this is the "bad" cholesterol that may build up in your arteries, forming plaque that narrows your arteries and makes it harder for the blood to get to your heart.