Keifer is GENERALLY as effective as active, which for yoghurt is pretty high.
Be aware, though that a lot of outfits sell keifer that is sorta fake.
REAL keifer u can recognize cuz it contains live organisms and if left at room temperature for a couple hours their byproduct, co2 gas, will make a sealed top POOCH OUT.
If you leave it out for half a day and the top doesn’t pooch up and out then you know everything that was in there is dead and it would not have really helped your gut.
(generally keifer is better than 90% of yoghurts)
activA, not active. stupid spellcheck.