Anecdata/placebo/whatever: I use BioGaia's Gastrus tablets and they increase my quality of life noticeably, and I can tell when I've been off them for a while. I got refrigerated deliveries of probiotic yoghurt drinks for a while previously and in addition to the faff, didn't notice as good results.

Additional Anecdata: I head about BioGaia's Gastrus tablets here on HN a couple of years ago and they have dramatically improved my wife's quality of life as well. She suffered from significant GI problems. We bought a pack of the BioGaia tablets based on an anecdote here. Within about 3 weeks her year-long GI problems were gone. She discontinued the tablets and the GI issues stayed away. About 18 months later, after a period of heavy stress and travel, her GI issues returned and then disappeared again after another round of BioGaia tablets.