Eli5 How does cholesterol get from your intestine into your arteries and how does ingested fiber help lower the cholesterol in your arteries?
Digestive enzymes make cholesteral soluble in blood plasma. This new solution diffuses through the intestinal wall into the bloodstream which carries it throughout the body along with the rest of our nutrients. These diffuse into whichever cells have a lower nutrient concentrations, or which are equipped to actively bind with and absorb them.
Fibre increases food’s volume to nutrient ratio and softens the digestive slurry. Mixing fibre into your food shortens the time it spends in your digestive tract, and prevents some nutrients from saturating the bloodstream during digestion. In other words, it makes rates of absorbtion more uniform.
The majority of the cholesterol in your blood is produced by your own liver. This is why dietary cholesterol is known to have little effect on overall cholesterol.
This cholesterol is then stored in the gall bladder, which feeds it into the digestive system to help with digestion. It is then reabsorbed by your intestines.
Fiber can impact this in two ways:
1. Insoluble fiber tends to move the contents of your digestive system through the intestines more quickly, so there is less chance for the cholesterol to be reabsorbed.
2. Soluble fiber can absorb cholesterol and then carry it out of your body.
As a result, proper use of fiber is one of the best ways to bring down high cholesterol and is more effective than limiting dietary cholesterol.
Most of your cholesterol is produced by your liver. The amount you get from your diet is not significant in most cases.
It goes from your liver to your stomach and then the intestine through the bile (a liquid secreted by the liver to the stomach).
It gets from your intestine to your liver by Chylomicrons also known as Ultra low-density lipoprotein (ULDL).
It gets from your liver to your cells through very low-density lipoprotein (VLDL), which becomes intermediate-density lipoprotein afterward (IDL), and then low-density lipoprotein (LDL).
It gets to your arteries from Chylomicrons remnants and low-density lipoprotein (LDL).
It’s cleaned up from your arteries using high-density lipoprotein (HDL) which brings it to your liver.
If you have high HDL, they will clean your arteries and your arteries will get healthier with time.
Cholesterol is reduced by fiber because fiber reduces the absorption of cholesterol by the intestine, so more of the cholesterol produced by the bile is excreted when you poo. Also, some fibers are fermented in short-chain fatty acid by bacteria, and short-chain fatty acids increase the of HDL production by your liver.
First off, some cholesterol you eat and absorb, some you produce naturally. Cholesterol is a required ingredient in a healthy human body but the problem is clearly that too much is bad, and sometimes we get too much from food, or we make too much ourselves.
Long story short, cholesterol gets from our intestine to our arteries the same way all of our nutrients do – our intestine is covered in blood vessels and nutrients move from our intestines, through the walls, and into the blood vessels directly. Our arteries are part of our blood vessel system and there you have it.
Ingesting fiber helps because it shortens the time digested food sits in your intestine before it’s expelled. The more fiber you eat, the less time the cholesterol in your food has to make it’s way into your blood vessels.