Cholesterol is a type of lipid or fat-like substance produced by liver naturally. Cholesterol is necessary for the formation of cell membranes, certain hormones and vitamin D.
Cholesterol doesn’t dissolve in water, so it can’t travel through your blood on its own. To help transport cholesterol, your liver produces lipoproteins.
Lipoproteins are particles made from fat and protein. They carry cholesterol and triglycerides (another type of lipid) through your bloodstream. The two major forms of lipoprotein are low-density lipoprotein (LDL) and high-density lipoprotein (HDL).
If your blood contains too much LDL cholesterol (cholesterol carried by low-density lipoprotein), it’s known as high cholesterol. When left untreated, high cholesterol can lead to many health problems, including heart attack or stroke.