I suppose the wealthy aren't doing it, so why not tread on those dirty poors a bit harder - it can't be a health issue if we make it a criminal one, eh gents?
nitrous inhibits b12 production, so if you use a shitton in one sitting then take a few weeks break youll be fine just supplement b12
but if u use a little bit periodically over a couple days that could start to degrade your nerves permanently due to lack of b12.
but you cant produce less than zero and any nitrous puts you at zero so if youre gonna use it do big one night binges then take a month off and supplement b12 for a bit. in this case its theoretically pretty harmless.