How does exercise lower cholesterol levels?

• A. Stimulates enzymes to move LDLs from the blood to the liver
• B. Inhibits hepatic cholesterol synthesis
• C. Increases intestinal absorption of cholesterol
• D. Increases breakdown of HDL

Answer: (A)

Regular exercise lowers LDL cholesterol mainly by increasing the liver’s uptake of LDL particles. When you exercise, the liver upregulates LDL receptors, which enhances receptor-mediated endocytosis of LDL from the bloodstream into hepatocytes for processing and clearance. This boosted clearance lowers the amount of LDL circulating in the blood. The other ideas don’t fit as well: increasing intestinal cholesterol absorption would raise blood cholesterol, increasing breakdown of HDL would reduce the “good” cholesterol (and exercise actually raises HDL), and inhibiting hepatic cholesterol synthesis is more the realm of certain medications than a primary effect of exercise. So, the concept that exercise promotes removal of LDL from blood to the liver best explains how it lowers cholesterol levels.