the difference between sugar the food and blood sugar?


I dont know why but this is one of those things I just cant make sense of even with Google. So is sugar found in blood and the body there from eating sugar or a natural accurance regardless of diet? Is sugar as a food and blood sugar completly seperate things? This has bothered me for 2 decades. Explain it like I am 3 please.

In: Biology

They’re 2 different compounds. Table sugar is sucrose, blood sugar is glucose. Blood sugar is the way by which energy is transported to your cells, which is why your blood sugar goes up after eating regardless of whether you were eating something with sugar in it.

There are different types of sugar
The main three are Glucose, sucrose and fructose

Glucose is the one that our blood uses to move energy around our body,

Glucose is sometimes found in foods, but when you think of “sugar” and imagine a bag of sugar, that is sucrose.

Your body is able to change sucrose into glucose when you’re digesting it, which lets the sugar you eat get into your blood to energize you

The confusion probably arose from the fact that “sugar” is a very very broad term that is often used to describe the whole class or a particular example. Saccharides are all sugars, there are monosaccharides like glucose, fructose, galactose, etc, there are also disaccharides like sucrose (table sugar, which is glucose and fructose linked together), lactose, maltose, etc which are two monosaccharides linked together chemically, then there are oligosaccharides which have usually 3 to 10 (some also count disaccharides as oligo and some go past 10) like raffinose, stachyose, etc, and finally polysaccharides which are quite long chains of sugars (can be quite branched too like a very complex network) like glycogen, starch, cellulose, chitin, etc. These are all sugars.. Some of them we can use in our body and some not (like cellulose). When we eat them (like vegetables, fruits, meat, etc), we break them down into monosaccharides to absorb them into the blood, and then they enter cells and get used up. As our energy carbohydrate storage caches are glycogen, which uses glucose, and as most our cells prefer it, and as the entire metabolic network relies on it (we can make things with glucose and break things down towards glucose, or things can enter glucose metabolic pathways, whether building or breaking, in the middle via special enzymes for them), glucose is by far the most detectable monosaccharide in our plasma (fluid part of blood), the rest do spike a bit after a meal, but are quickly used up or stored, and this is done by liver and some other cells. So when we say blood sugar, we mean level of glucose. We also have a LOT of other uses for sugars, like adding them on proteins and coating cells with them (usually oligo or polysaccharides), we even use sugar derivatives as a kind of signaling system sometimes (adding them transiently to proteins to change their function, like in *O*-GlcNAcylation).

Food sugar is sucrose and blood sugar is glucose.

Glucose is the sugar that the body can use; all sugars are broken down by the body to turn into glucose before they can be used.

Glucose is kept in the blood to give all the cells energy when they need it.

Food sugar is broken down by digestion, the breaking down of food by the stomach, and sucrose has to go through a chemical transformation to turn into its usable form- Glucose!

Ok. Let’s begin with the beginning. Sugars aren’t a single substance. They’re a group of chemicals. There are a lot of sugars. For example, starch is a sugar. Cellulose is also a sugar. When we say “add some sugar to my coffee”, we refer to the common name of a compound called sucrose.

Sugars are basically a chain. Their properties vary based on the type of links, and the length of the chain. There are a lot of types of links, but we’ll concern ourselves with the most common one: glucose. Now, most of the stuff we consume contains sugars made from these links. And we make the links consumable by breaking the chain. So, if you eat a longer chain and a shorter chain, but with the same links, the end result will be the same. Only the quantity will vary.

For example, let’s have a slice of bread with some chocolate. The slice of bread has starch, which is a very long chain of glucose, and the chocolate has a short chain of glucose, aka sucrose (it has only two links). Now, if we break down the chains, what do we get? Glucose on both sides.

But in order to use the glucose we’ve just made, we have to carry it to the cells. How do we do that? We put it in the blood. Hence blood sugar.

This is why cows, for example, also have sugar in their blood, despite never eating any, well, sugar. They can break down cellulose chains into links, which makes them usable.