The series by Peter Attia is one of the most accessible and informative lectures on Cholesterol that I have found. Here are some excerpts.
"...standard cholesterol testing (including VAP) is largely irrelevant and you should have a lipoprotein analysis using NMR spectroscopy ...This topic bears an upsettingly parallel reality to that of nutrition 'science' in that virtually all health care providers have no understanding of it and seem to only reiterate conventional wisdom (e.g., 'LDL is bad,' 'HDL is good')"
"Cholesterol is "just" another fancy organic molecule in our body, but with an interesting distinction: we eat it, we make it, we store it, and we excrete it – all in different amounts."
"Cholesterol, a steroid alcohol, can be 'free' or 'unesterified' ('UC' as we say, which stands for unesterified cholesterol) which is its active form, or it can exist in its 'esterified' or storage form which we call a cholesterol ester ('CE')"
"Cholesterol exists in 2 forms – UC and CE – and the form determines if we can absorb it or not, or store it or not (among other things)."
"About 25% of our daily "intake" of cholesterol – roughly 300 to 500 mg — comes from what we eat (called exogenous cholesterol), and the remaining 75% of our "intake" of cholesterol — roughly 800 to 1,200 mg – is made by our body (called endogenous production). To put these amounts in context, consider that total body stores of cholesterol are about 30 to 40 gm (i.e., 30,000 to 40,000 mg) and most of this resides within our cell membranes. Every cell in the body can produce cholesterol and thus very few cells actually require a delivery of cholesterol. Cholesterol is required by all cell membranes and to produce steroid hormones and bile acids."
"Of this 'made' or 'synthesized' cholesterol, our liver synthesizes about 20% of it and the remaining 80% is synthesized by other cells in our bodies."
"Plasma cholesterol levels (which is what clinicians measure with standard cholesterol tests) often have little to do with cellular cholesterol, especially artery cholesterol, which is what we really care about. For example, when cholesterol intake is decreased, the body will synthesize more cholesterol and/or absorb (i.e., recycle) more cholesterol from our gut."
"Only free or unesterified cholesterol (UC) can be absorbed through gut enterocytes."
"Much (> 50%) of the cholesterol we ingest from food is esterified (CE), hence we don't actually absorb much, if any, exogenous cholesterol (i.e., cholesterol in food)."
"Most of the cholesterol we eat is not absorbed and is excreted by our gut (i.e., leaves our body in stool). The reason is it not only has to be de-esterified, but it competes for absorption with the vastly larger amounts of UC supplied by the biliary route."
"Re-absorption of the cholesterol we synthesize in our body is the dominant source of the cholesterol in our body. That is, most of the cholesterol in our body was made by our body."
"One of the unfortunate results of the eternal need to simplify everything is that we (i.e., the medical establishment) have done the public a disservice by failing to communicate that there is no such thing as 'bad' cholesterol or 'good' cholesterol. "All cholesterol is good! The only 'bad' outcome is when cholesterol ends up inside of the wall of an artery, most famously the inside of a coronary artery or a carotid artery, AND leads to an inflammatory cascade which results in the obstruction of that artery (make sure you check out the pictures in the links, above). When one measures cholesterol in the blood – we really do not know the final destination of those cholesterol molecules!"
"Eating cholesterol has very little impact on the cholesterol levels in your body. This is a fact, not my opinion. Anyone who tells you different is, at best, ignorant of this topic. At worst, they are a deliberate charlatan. Years ago the Canadian Guidelines removed the limitation of dietary cholesterol. The rest of the world, especially the United States, needs to catch up."