Neon Pointed

Why does urine turn neon yellow after taking a Vitamin B Complex pill?

I’m taking it because I have low iron and endometriosis and was told it would help that. But now my urine is neon yellow. I know it’s from the vitamin, but can someone explain how/why this happens and if there is anything that can be done to stop it (besides just stopping the vitamin)? It’s not like it’s a huge problem, I can live with it, I’m just curious!
10 points for best answer!

It basically means that the vitamins in the pill that your body does not absorb is getting flushed out into your urine.

http://www.eclecticphysician.com/archive.php?action=Nbr&Nbr=86

JUST ANOTHER NEON NIGHT (BROOKS&DUNN)