system
Given the following post, respond as if you're commenting on Reddit:
human
Why is Vitamin C not part of the Vitamin B complex?

I don't get how niacin is closer to Vitamin B12 than Vitamin C. Vitamins C and B12 are both cofactors in protein synthesis, while niacin is a redox agent.
gpt
It's because of historical reseasons.

The first vitamins were classified as water or fat soluable with alphabet designation A, B, C, D, E, F, K, H, I, J, K, G etc

While analyzing Vitamin B then designated as Thiamin - Researchers Smith and Hendrick realised that they are dealing with two substances so we renamed vitamin B to Vitamin B1 and B2. Then similar divisions hapenned with other vitamin B's and some older designates like vitamin H or vitamin F were reclassified (H is biotin B7 and vitamin F are EFA's)  and the whole alphabet soup of vitamins went to hell and we are left with todays classificaiton.