eli5: Is cholesterol actually bad for you?

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So, I’ve always assumed it was. Everyone says that it is and I’ve had no reason to doubt it. Now I’ve heard about ‘studies showing that it has no link to heart problems’ etc. etc. and google of course justifies anything you search so is cholesterol still a bad thing or has that actually changed?

In: 2

It all depends on where it is. High cholesterol in your bloodstream is a bad thing, leading to deposits in your arteries.

High cholesterol in your food just means easy to digest fatty acids for your digestive system. So you probably don’t want a LOT of high cholesterol in your food, but it’s the sugars that will make you fat if that’s what you’re worrying about.

Not having cholesterol in your food is generally better, as those fatty acids are also linked to cancer in the GI tract, but having a bit of butter on your toast won’t automatically give you a heart attack, and avoiding it in your food altogether won’t protect you from weight gain or hard arteries.

Cholesterol is mainly of two types:High Density Lipoprotein (HDL) or good cholesterol. It serves a protective function against coronary heart disease as it carries cholesterol to the liver where it is excreted out via bile Avocados,olive oil, fatty fish etc. are good sources of HDL.
Another kind is Low Density Lipoprotein(LDL) or bad cholesterol,found in junk foods. It deposits on the walls of blood vessels and make them more stiff increasing risk of coronary heart disease.

There’s some interesting history here. It didn’t take long for pathologists dissecting human bodies to figure out that the plaques that lead to strokes and heart attacks are made out of cholesterol. Solution? Don’t eat too much cholesterol!

Or so they thought.

So it turns out, unsurprisingly, that if you have more cholesterol in your blood, it builds up in the walls of your blood vessels. This is called “atherosclerosis.” The higher the cholesterol, the faster the atherosclerosis gets worse. Which is like a crusty buildup on the inside of your blood pipes, which eventually gets bad enough that your brain and heart don’t have enough oxygen.

But the weird thing is, and this took scientists a while to figure out, that how much cholesterol you eat doesn’t have a whole lot to do with how much cholesterol is in your blood. Except for a few people with certain genetic conditions. More most people, if you eat more cholesterol, your liver makes less cholesterol. If you eat less cholesterol, your liver makes more cholesterol.

So here’s the real bamboozler. How much cholesterol your liver makes depends on how much energy the liver thinks is available. If you eat a lot of sugar or other simple carbs, the liver will think that there is loads of spare energy available, so it will make more cholesterol. If you have diabetes, the liver thinks there is loads of spare energy. The liver funnels that spare energy into making more cholesterol. So the weird thing is, how much sugar you eat has a bigger effect on your cholesterol than how much cholesterol you eat.

So cholesterol in the blood is actually bad for you, which is why statin medications can reduce the chances of heart attacks and strokes. But eating cholesterol is not bad for you, unless you have certain genetic conditions. Eating sugar is bad for you.