500 CFU's?? Holy that's a lot. I remember having diarrhea after just taking 10 billion CFU's. This stuff would kill me...
Yeah if you got diarrhoea maybe it was from inulin/FOS in your supplement.
Half the reason I went with Elixa (the other half was that it was high dosage) was that it contained NO inulin/fos/similar fibre. They always talk about inulin/FOS feeding the good bacteria and all this stuff (e.g. 'maximises the effect by 1000x!') but for me it just gives me massive bowel discomfort. And it's obvious why really: if it feeds bacteria and you have an excess of bad bacteria in your gut that are gives you problems... then supplying more food for them to ferment is just going to aggravate the condition. It's not like these oligosaccharides can selectively only feed good bacteria (although some places claim they do, i have had first hand pain/bloating that begs to differ!!).
Example: I took one which was a mix of psyllium, FOS/inulin and probiotics. I never have problems with psyllium or probiotics but that one gave me terrible pain and bloating. (bloating within a few hours and then deep abdominal pain after about 10 hours for another 12+ hours).
Not had problems with this Elixa brand and i've taken quite a few. (i'll also add that I would get diarrhoea pretty easily by, for example, drinking milk. They've actually HELPED in that regard i'd say.)
I'd be interested to see how it works for several people. I've only read 5-10 reviews of it so far and i guess it is quite new.