According to WebMD, high cholesterol occurs when there is an excess amount of the lipid cholesterol in the bloodstream of a patient. Cholesterol is an essential lipid in the human body, but too much of it can be harmful.
According to WebMD, there are two different types of cholesterol. LDL cholesterol is the bad cholesterol that can increase a patient's risk of heart disease, heart attack and stroke. HDL cholesterol is the good cholesterol that can reduce a patient's risk of heart disease, heart attack or stroke. Patients with high cholesterol often have too much LDL cholesterol and not enough HDL in their bloodstreams.