[ELI5] What makes a chemical-compound be declared/considered a Vitamin


There are so many substances that you can take for health reasons (as dietary supplements) such as minerals, salts, amino acids, etc. What makes a particular chemical be classified as a type of Vitamin?
For example, Ascorbic acid is Vitamin C.
At the same time, Citric acid (in orange and lemon), acetylsalicylic acid (aspirine) , butteric acid, acitic acid (vinegar), all of these are not vitamins! Why

What does a vitamin do, that a non vitamin doesnt.

Why are there vitamins b6, b12, b1. Is there a vitamin b5 or b9?

In: 8


Vitamins are molecules that our body needs in small quantities to survive but can’t make itself.

These are sometimes things that our ancestors got enough of in the food they ate that evolution simply didn’t prevent them from losing the ability to make it itself.

For example many animals can make vitamin c themselves but at some point our ancestors lost the ability to do so, but that wasn’t really an issue since you can get it by eating all sorts of fruits and stuff.

That worked out well until people started staying too long in places without fresh fruit, like on ships, and got scurvy as a result.

The naming scheme is a bit confusing because we started labeling things a vitamins before we understood exactly how our body and our cells do organic chemistry.

We labeled some stuff as vitamins that later turned out to not be vitamins.

Either it turned out we didn’t need the stuff to survive after all. Or our body can actually make it itself from other stuff or in the case of what used to be vitamin F it turned out we need and can’t make it ourselves, but also we don’t just need it in small quantities, we need lots of it.

Some vitamins turned out to belong into the group of Vitamin B things.

So there is no Vitamin B4 or B8 anymore because we can make that ourselves and to be Vitamin H was renamed Vitamin B7.

The naming system is complicated.

The main point is that vitamins are labels we give to things we need in small quantities in our diets.