I recently did a food intolerance test and my immune system reacts to all the products made out of cow... Kefir included. 

So would test that out. 

Really, there's no solution that suits everybody. Need to do your own research. 

Btw, was eating carnivore for a bit of time & fucked up my digestive system & liver too... Just couldn't handle as much protein & now have to eat lots of veggies (and beef too 2x per week) to fix it up. 

In other words - do your own research.  

 I don’t think kefir is for everyone, just like not everyone has the enzyme to process milk proteins in their genes. I would question what your food ate? Were you eating grain fed ruminant meat? Did you cut out everything but meat and clean water to start? It does take some time to recolonize your colon, your liver has to switch to metabolizing fat, and your bile production takes a bit too.

What liver tests did you have done? 

 I've done blood tests & immune response tests. 

And as for meat - I was eating grass-fed one. I was eating more things than meat for sure, though that was 70-80% of my diet. 

95% paleo diet I'd say.