Lipid-lowering medications: Statins

Statins lower overall lipid levels in the body, and work by inhibiting the enzyme HMG-CoA reductase, which is the rate-limiting step of cholesterol metabolism.

They are an incredibly important class of medications because they’ve been shown to decrease complications associated with cardiovascular disease like strokes, heart attacks, and peripheral vascular disease.

Although it’s got a bad reputation, cholesterol is actually a critical component of our cells and is used to build the cell membrane.

It also has other uses like the synthesis of steroid hormones, vitamin D, and bile. Normally, we get our cholesterol from the food we eat, but it can also be synthesized by the liver.

So when we eat a box of chili fries, the fats and cholesterol are absorbed in the small intestine. However, they’re not water soluble, so they can’t travel freely in the blood.

To fix this, our body makes shipping boxes called lipoproteins.

These containers consist of a shell made of phospholipids and protein tags that act as instructions for their destination.

So after absorption, the small intestinal cells package the fats and cholesterol into the largest but least dense lipoproteins, called chylomicrons.

These are released into the lymphatic system and then enter the bloodstream via the subclavian vein. Then they travel through the blood to reach adipose tissue and the liver.

Now, the liver can also synthesize intrinsic cholesterol through the mevalonate pathway, which happens in the smooth endoplasmic reticulum of liver cells.

It begins with 2 acetyl-CoA molecules getting joined together by the enzyme acetyl-CoA acyl-transferase.

The result is a 4-carbon molecule called acetoacetyl-CoA.

Next, the enzyme HMG-CoA synthase combines acetoacetyl-CoA and acetyl-CoA to form a 6-carbon molecule called 3-hydroxy-3-methylglutaryl CoA, or HMG-CoA.