Cholesterol is a lipid molecule that helps maintain the structure of cell membranes, and is a precursor to steroid hormones, bile acids, and vitamin D.
Although, every day, some new cholesterol comes in through the diet, most of the cholesterol we need is obtained through recycling existing cholesterol.
Most of that recycling happens in the intestines and is facilitated by bile acids which help us reabsorb cholesterol and bring it back into the bloodstream.
There are two main types of cholesterol: HDL or High Density Lipoprotein which is sometimes called “good cholesterol”, and LDL or Low Density Lipoprotein which is sometimes called “bad cholesterol”. But good and bad is overly simplistic, and like all things - the subtleties matter.
LDL is produced by the liver and it carries cholesterol out to the rest of the body.
If all of the cholesterol from LDL is not completely distributed to the peripheral cells, then HDL brings some of that cholesterol back from the peripheral tissues and sends it to the liver.
Now, what makes LDL bad and HDL good is that, whenever there’s a high blood concentration of LDL, the LDL can be ingested by macrophages that sit along vessel walls, forming atherosclerotic plaques.
Over decades, large atherosclerotic plaques can lead to myocardial infarctions, strokes, and peripheral vascular disease. That’s why we want to keep LDL blood levels under control.
On the other hand, HDL can remove cholesterol from cells and that can help reverse the process of atherosclerosis.