"Good" Cholesterol? "Bad" Cholesterol?

GOOD and BAD Cholesterol?

These terms have long been troubling because only one kind of cholesterol is listed in the biochemistry books. So, how could there be good and bad kinds?

There is indeed only one kind of cholesterol. But there seems to be two different cholesterol transfer or transporter proteins. One type transfers cholesterol TO membranes such as the arterial walls, and the other type transfers cholesterol AWAY FROM membranes.

Eating high density lipids (whatever HDL's are!) triggers hormones that favor the activities of the "take-away" transporters. As the activity of the "deposit" transporters is rather constant, it seems that what is important is the overall ratio of high to low density lipids (LDL's) you consume raises or lowers the activity of the "take-away" transporters, and thus the ratio of "take-away" to "deposition".

But there are also other factors that deal with the transport activities. A major one is physical activity and starvation. No matter what proportion of heavies to lights you consume, it you are a miner and burn 18,000 calories per day, you don't deposit cholesterol to anything above what membranes absolutely need to be called membranes.

Now the question in mind is what are "heavy" and "light" density lipids. Is it physical density or is it just another figure of speech? (Don't look in this website for the answer!)

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