High-density lipoprotein, or HDL, cholesterol levels below 60 milligrams of cholesterol per deciliter are less than ideal, states Mayo Clinic. In rare instances, low levels of low-density lipoprotein, or LDL, cholesterol and total cholesterol can increase risk of cancer, anxiety and depression.
LDL cholesterol is known as the "bad" cholesterol because excess amounts collect in blood vessel walls, forming "plaques." These plaques narrow blood vessels and can block blood flow, resulting in coronary artery disease. HDL cholesterol, known as the "good" cholesterol, collects excess cholesterol in the body and carries it to the liver, reducing risk for coronary artery disease, states Mayo Clinic.