The answer takes more than 5 minutes, so, by tradition, I answer in the form of a publication.
Question: Doctor, and yet let me ask you, glucose, dextrose and several other names with the same chemical formula are the same thing? And if the formula is the same, but the shape of the molecule is different, how is it?
Answer: Dextrose, glucose and fructose have one chemical formula: C6H12O6. These are isomers.
Fructose
Fructose and glucose are structural isomers. They have the same formula, but the atoms are arranged in a different order. By some coincidence, both of these isomers are sweet, and we can use them as a source of energy.
I have a suspicion that we can digest fructose and glucose only because both are constantly found around us in nature.
Dextrose
Dextrose is common glucose. It is called dextrose because it is one of two optical isomers of glucose. It is also called D-glucose. This is dextrose. It is called the optical isomer because it has a sibling, L-glucose.
L-glucose
It has the same chemical formula, but is stacked in space like a mirror image of glucose.
It turns out that the difference between L-glucose and D-glucose is even less than that of D-glucose with fructose. But their properties are very different.
L-glucose is rare in nature. It is produced chemically. It also tastes sweet like glucose, but our body does not absorb it.
There was even an idea to use L-glucose as a sweetener. Have you presented? It would taste the same glucose, but it is not absorbed. This could be done if it were not for the synthesis of L-glucose in a complex chemical way. Because it does not lie underfoot. Well, that is, it turned out to be too expensive to make a sugar substitute from L-glucose.
But it is used in medicine as a laxative or for some kind of research.
Briefly speaking
These are all isomers with the same formula, but different properties. This is often found in nature.
