I think the pills are a bit cheaper.

But I would normally get it from food sources if it's easily available.
I see no point in taking pills/tablets because there are other nutriets in yogurt making it worth consuming. I know there's only a few grams of protein and a lot of sugar, but I'm not drinking a gallon of it daily. So the heck with it. =P

Should you prefer yogurt, go for natural flavour yogurt (no sugar, no fruity stuff) or Yakult.

Yakult publishes the number of CFU of its probiotic strain on the packaging. 30 billion in a bottle. That's a lot of bac for your buck. Guaranteed to reach your colon.
It's one of the highest, even compared to Yakult from other countries which are normally 10 billion in a larger bottle (e.g. S'pore, China).
Oh, I just found out that there's a new low sugar version of Yakult. I should go try it. =)

And if you could get a group of 20 persons, you could contact Yakult for a factory visit. They always welcome people to visit them.
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All yogurt have probiotics. And probiotics pills are supplements, not drugs or medicine. GP takde.
Pharmacy will carry the tablets, and kedai-kedai runcit pun ada yogurt.