High-density lipoprotein (HDL), commonly known as “good” cholesterol, actually plays an important role in transporting bad cholesterol away from the arteries and back to the liver. However, low-density lipoprotein (LDL) is the “bad” cholesterol, as it can build up in the blood vessels, leading to hardening of the arteries, known as atherosclerosis, and increased risk of heart attack and stroke. Therefore, it is important to keep LDL levels low and HDL levels high. Unhealthy lifestyle choices, such as lack of exercise, smoking, and unhealthy diet, can cause LDL levels to rise and HDL levels to drop.