We have talked about this vitamin before but I need to refamiliarize with it.
Red, kombucha as well is not too popular in Italy, at least I've never tried it, whereas I know better the milk culutures like yogurt and kefir. I've been making my kefir for a while now and it's exceptionally good. I recently tried soymilk kefir but it turns out pretty revolting, maybe I need to use the specific starter for water kefir.
Kefir fermentation appears to yield the vitamin K2, which yogurt does not contain