I know that this is going to stray somewhat off topic, but oh well...
As for the apple juice given to children to treat constipation, it's done primarily because they like the taste without having to add stuff to it to mask the flavor, and the relatively higher naturally occurring levels of malic acid, not so much the sugars/fermentables at all, that are responsible for the results.
As for the yeast, hefeweizens are my #1 preferred beer, and I actually pour the yeast into the glass. Everyone's always called me various things for doing so, but then I accidentally found this -
http://beeradvocate.com/articles/270 - read the 4th paragraph down. Wow, I was actually doing it "right" after all...??? No one that drinks our hefeweizen ever has a problem with gas or the runs, especially not me and I sometimes even take their bottles and dump (neheheheh, I said dump) the yeast into my glass. OTHER beers, though - nope. IDK why, I just don't do it.
As for hops.......................... well, SOME people actually have a problem with hops and it can cause the exact same thing as what many people (possibly erroneously) attribute to the yeast. And, as the above linked article points out, we here in America LOVE to load the hops into every beer, kind of like how most people can't eat chicken wings unless they use enough hot sauce to blast their prostate into the next county. Me? I don't like hot sauce (Tobasco = great, the rest = no thanks, lol!), and I like a sane amount of hops, that's why my affinity for German/Bavarian hefe's. And, maybe, why I drink the yeast and don't have any issues? But as for me and hops, as an herbalist I already know that I do fine with hops when used within the context of herbal matters, while a few others do not, so --- again, can't say for certain.
ANYWAYS, all I'm saying is that it's not necessarily the yeast that ought to always be getting the blame.
And btw, hops wasn't always a part of the ingredient list for beer. Hops are a great anti-microbial and helped to make the grain crop (after all, beer was once-upon-a-time just a way to preserve the grain harvest in liquid form and keep it from pests and spoilage) last almost 3-times longer than it would have otherwise; why do you think IPA's came to be? They used several times as much hops to help preserve it on its longer than normal trip, helping to ensure that it would still be preserved and drinkable when it got there (the sea trip from England to India). But today, beer is ALL about the hops to most people. Like hot sauce on chicken wings.
"**** the wings, HOW HOT ARE THEY?!?!?!"
One real-life example of this --- a few months ago, there was an informal gathering, mostly of family, and it sort of turned into a beer-tasting event, meaning that several of us brought homebrew and also there was a lot of BMC etc. Well, everyone was pretty much locker-room about "oh yeah" the darker and more hoppy the beers were the better they had to be and the more "oh yeahs" they got. But my favorite hefe? Didn't get much more than a lot of "yeah, that's okay" kind of reviews, but all of mine was consumed long before any of the others; in fact a lot of the darker high-hops beer was taken home with them that brought 'em.
My wife spent some time in (West) Germany back in the mid-70's, and she loves the hefe's that I brew because it reminds her of the beer they served regularly in that region where she stayed. I know, it's purely preference, I'm just saying - don't always blame just the yeast.
This isn't a slam against dark or hopaholic beer - I love them too, NOTHING delivers so much as they can and do give in a beer, they're just not my first choice for a steady diet. For my everyday brew, FOR ME, it's a hefe. With the yeast.
After all, "hefe" is German for "yeast."