I know that a diet high in trans fats can lower the levels of “good” cholesterol and raise the level of “bad” cholesterol in your blood. My question is how? Is this known? I’m trying to Google for it, but while I can find lots about how trans fats are capital-E EEEEEVIL but not exactly what they do in the body.
AFAIK, which ain’t a lot, and isn’t terribly up-to-date, trans fats, like saturated fats, lead to “down regulation of the LDL receptor”. In other words, they cause your body to be less able to clear (the bad) LDL cholesterol from your blood.
Normally, LDL cholesterol, like so many other substances, compounds, and molecules, is taken up by cells via a specific receptor on their surfaces (in this case, for LDL cholesterol). This leads to it being removed from the bloodstream. The fewer, or less active receptors you have, the more LDL cholesterol will accumulate. So, trans fats, lead to a decreased ability of your LDL cholesterol to be cleared from the bloodstream.
Since they’re not being cleared, rapidly at least, from the blood stream, the LDL cholesterol has time and opportunity to be “attacked” or “modified” by all sorts of chemicals while it circulates. Some of these changes (e.g. oxidation) are felt to contribute to LDL cholesterol’s ability to promote atherosclerosis. In other words, oxidized-LDL cholesterol is quite toxic to the lining of the blood vessels (and also causes all types of other nasty and/or undesirable effects there).
They don’t “DO” anything. That’s the beauty of them!
Thanks, KarlGauss! Very informative!
Is the amount of LDL receptors one of the genetic factors that makes it so hard for some people to decrease their cholesterol levels though lifestyle changes?
Absolutely!
And, another possibility is that a person’s LDL receptors may be normal in number but abormal in function.
Generally, for everyone, the fewer LDL receptors you have (or, equivalently, the more abnormal their function), the more cholesterol your body makes. That is why dietary changes tend to have limited effect. In fact, most of your cholesterol is from what your body makes, not what you ingest.
The more LDL receptors a person has, the easier it is for their cells to pull in cholesterol from the circulation (via those LDL receptors). There is less need for their cells to manufacture cholesterol. Conversely, the fewer LDL receptors a person has, the harder it is for their cells to pull in cholesterol from the circulation. There is a greater need for their cells to manunfacture cholesterol.
Fascinating! Thanks again!
I can’t resist adding that the so-called “statin” drugs work by preventing your cells from making cholesterol. As a consequence, the cells must get their supply of cholesterol by pulling more in from the blood stream (via increasing their LDL cholesterol receptors). Hence, LDL cholesterol levels in the blood stream drop.
If a person has no LDL receptors (a genetic disease), then statin drugs don’t work, and can’t work, to lower their LDL cholesterol levels in the blood. They have no LDL cholesterol receptors to increase).
After reading the rest of your interesting information, I was just about to ask what statin drugs do.
So if you have no LDL receptors at all, is there a treatment? Or do you just succumb to heart disease early in life?
In the past, youre’ right - people died from it, and died early. Often in their teens, or earlier.
Now, there are two treatments that can be used (AFAIK).
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LDL-apheresis: Basically this involves exposing a patient’s entire blood contents to an “LDL-magnet” (i.e. a column impregnated with an antibody that binds LDL cholesterol). In this way, the LDL cholesterol is removed from the body.
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Liver transplant: this restores liver cells (at least) to the body which are capable of synthesizing and expressing functional LDL cholesterol receptors. Hence, the LDL cholesterol is then removed from the blood in the usual manner.
They turn you into a fan of Knight Rider.