Goomba replied:

>> I'd guess that some kind of buttermilk smoothie would also be good
>> at repopulating bacteria.
>
> Only if the buttermilk has live cultures, which I've never heard of? I
> could of course have missed it?
> Yogurt with live cultures and lactobacillus acidophilus milk help restore
> the normal flora that illness or antibiotic use kill off.
> Goomba

It's called "active buttermilk." It's fairly common.

Bob