What is the main effect of statins on cholesterol levels?

Statins are primarily known for their ability to lower low-density lipoprotein (LDL) cholesterol levels in the bloodstream. The main mechanism through which statins exert this effect is by inhibiting the enzyme HMG-CoA reductase, which plays a crucial role in the hepatic synthesis of cholesterol. When statins inhibit this enzyme, there is a decrease in cholesterol production within the liver, leading to an upregulation of LDL receptors on hepatocytes. This increase in receptor density allows for more efficient clearance of LDL from the bloodstream, resulting in a notable reduction in serum LDL cholesterol levels.

While statins may have some effects on other lipid parameters, such as potentially increasing high-density lipoprotein (HDL) levels or modestly affecting triglycerides, their predominant and most clinically significant effect is the reduction of LDL cholesterol. Therefore, choice B accurately captures the primary action of statins in lipid management.