My DH has always made bread and after a recent cottage holiday in Wales where we had a home made sourdough loaf he decided to try one himself. We got a starter from the local farm shop and away he went. It really is nice bread with no fat or sugar in. You use the same starter , keeping it in the fridge and feeding it with flour when you want to make a loaf- we call our starter 'Sid. There are lots of u tube videos about how to do it and Paul Hollywood has recipes. I can see that absence of sugar or added preservative might help with ibs, it's a lovely light loaf with a crunchy crust,toasts well too. It's not a speedy loaf to make ,it has to be proved overnight but it smells lovely when it's cooking.
Thorntrees