Work...issues

I have a friend on Facebook who often complains that one of her co-workers sings all the time.  She's not opposed to singing in general, she's opposed to BAD singing that goes on all day, all the time.  I think that would definitely grate on my nerves after a while but what about a co-worker with, shall we say, more offensive habits?

Okay, I work with someone who is well aware that they have digestive "issues" and yet doesn't seem to care that when they eat certain things, their body makes certain sounds that are EXTREMELY offensive to the rest of us.  Yes, I'm talking about burping and farting.  There, I've said it.  It's not a once in a while thing, it is daily.  They apologize, say 'excuse me' but basically, it makes me throw up a little with each sound they make because...and here's the kicker...when they sit down to eat the offensive food, they ADMIT that this is not good for them and they are eating it anyway.

THAT IS WRONG ON EVERY LEVEL!

If you want to eat stuff that makes you...make noise, do it at home!  Have it for dinner!  Why would you do that to the people around you?  We have ALL complained about it and they laugh!  You can't blame cluelessness because we have all said "STOP EATING THAT!" and told them why!  

I've been temped to go to the bosses but what do you say?  How do you, as an adult and without laughing, say that your co-workers digestive problems are becoming a problem for you?  Is there a way to say that without sounding stupid or petty?  I just don't know...