Basic Question -- Gas :)

It can also happen because a child is swallowing a lot of air when they eat or drink..... that air has to go somewhere!

Most of the healthy foods (fruits and veggies) cause gas. I would be careful if you start taking away foods. Try giving him a probiotic every day and see if that helps. Also make sure he is going poop regularly, he may not want to do it at school and that will cause a lot of gas as well. If it is really smelly then maybe he could be lactose intolerant. That would be the only reason I would think of the teacher saying something.

My first thought was a possible lactose issue as well. I wondered if his gas was really smelly thus people noticing it more! Very smelly gas is a sign of that, along with various other things like looser stools and a rash.

Has his diet changed in any ways recently? Has he started eating more of a particular fruit or vegetable? If so that could cause it. If not, then I like the ideas Jackie mentioned that it could be he isn't wanting to poop at school and is causing tummy issues. I would talk to him about it and observe his diet more closely before taking anything away.

It could be a lot of things.
Food allergy, constipation, intestinal bacteria are off, etc.
Try more fiber, have him eat some yogurt and drink plenty of plain water.
Keeping a food diary and noting his reactions will help you narrow down foods that are setting him off.
All of my family periodically goes through periods when we're gassy and stinky for no reason we can figure out and when that happens we'll take some activated charcoal capsules for a few days and that seems to clear it right up.

it could maybe be dairy. Has he had any broccoli? Hope he feels better

It is summer time, lots of good veggies and fruits being eaten raw.

I agree to make sure he is going to the potty enough, and give him a probiotic.

Any food high in fiber can cause gas. That includes a fair few fruits and vegetables.

The better question is is it causing any distress. If it isn't, who cares. If you wipe out every food that can cause gas you won't be eating very healthy, ya know?

What I mean is like my whole family loves artichokes! You could power a whole city with the after product. That doesn't mean we should stop eating artichokes, just perhaps avoid going out in public as a family.... :)