Does Superman need mouthwash?

[MrCheimison]

Superman's immune system and the latent energies of his internal organs would destroy bacteria.  Also, his 'force-field' pushes anything dirty off of him, which is why he never stays dirty.

Heshould need to eat for healing reasons, but his superior metabolism, toughness and the ability to survive off the sun would make eating superflous more than once every few months.  He also wouldn't need to breathe, and I can't believe such a big deal is made of this.  If he can internally metabolise sunlight he doesn't need oxygen (which humans use for making energy with food, something Superman doesn't really have a use for).  True, plants do use carbon dioxide to make sugars and carbohydrates, but Superman CLEARLY does not use carbohydrate energy, there is no way his level of energy could be obtained by that simple chemical process.  What he probably does is metabolise energy into a more reactive chemical (as solar cells do with batteries), although it's concievable that he might actually be able to charge or activate some sort of fission, fusion or Zero-Point energy field with solar radiation.  Being an extremely efficient rechargeble battery would explain his power source, such as a lead/sulphuric acide compound which released electricity and is converted in the process, then when electricity is run through it it once again turns back into lead and sulphuric acid.  Superman could also use the immediate free electrons created from the striking of photons upon his body (the photoelectric effect) for en energy, thus keeping him powered indefinitly as long as he was being bombared with sunlight.

[Tiberious]

Wait but wouldn't Superman still get dirty, I mean if you take a big block of solid steel and just leave it out. Maybe it wouldn't be destroyed for a long time, but it would sure get dirty. Also hair gets greasy doesn't it? So his hair would get dirty after a while.

[RedSunOfKrypton]

His personal force field keeps dirt away from him, and with efficient enough chemical processes in his body, his hair shouldn't get greasy, at least not for a very long time.

[Brainiac44]

That's postcrisis...

[comicfan]

I know that Superman doesn't need to eat, but does he eat anyway?  I imagine he does, either out of habit or to keep up appearances as Clark Kent.  

I'd bet that whatever germs and bacteria left by normal food to cause bad breath would be killed off in his mouth in short order.

[Gor-el]

Post crisis Supes has a decontamination organ that break offensive materials down into pure energy.

[RedSunOfKrypton]

And were he able to break even just offensive materials down into pure energy, he'd have all the energy he needed to do his super feats. Considering there's enough energy in a cup of coffee to boil away all the oceans on earth, if Superman can convert matter into pure energy then he's set as far as eating goes.

[Captain Kal]

The Critical Condition storyline established that Superman's digestive system converts food/matter into pure energy which implies that his body tissues reconvert that energy to matter in whatever form needed.

I believe RedSunofKrypton is referring to the zero-point energy in the volume of a cup of coffee which has the minimum estimated value he quotes.  The mass/energy conversion of a cup of coffee is actually much less and is probably around 3.2 megatons or what's needed to vapourize 3.2 million tonnes of conventional matter.  That translates into a cube of water just over 9 miles on a side which is clearly much less than even a small lake.  The minimum zero-point energy value is based on a cut-off distance value of around a proton radius (~10e-13 cm) which was more pulled out of the air than really substantiated; theoretically, no bottom cut-off length may be involved or it may be closer to the Planck length (1.616e-33 cm) which would yield a value 20 orders of magnitude much higher.