The thread title has "Activia" spelled wrong, BTW.   (Not that it probably matters all that much to people using the forum search engine.)

Activia and several of its imitators, for what it's worth, do not contain lactobacillus cultures. Not sure how important this is, but a friend's doctors recently gave him dietary admonitions following a bout of severe diarrhea, dizziness, and sweats, and they said "avoid dairy products except yogurt containing lactobacillus." I asked why, and they said the lactobacillus cultures counteract the tendency of dairy products to be hard to digest.   

When I first heard about Activia and similar yogurts "aiding digestion," I thought that sounded good.   Later I found - mostly via Saturday Night Live - that what they were mainly talking about was preventing constipation. It's an important distinction, because if you are more prone to loose stools than to constipation, I wonder if Activia and the like would be recommended for you.