Not a lot. Eating a full serving of one of these a day is probably enough .
I usually get the kefir in every morning. Greek yogurt maybe a few times a week. And sauerkraut when I want to or when it's meal appropriate .
There are other fermented foods you can look into. Those are just the three I eat most often.
And make sure you're getting these with live and active bacteria cultures. The kefir and yogurt are easy enough to find. Sauerkraut that hasn't been Pasteurized is a little tricky. I get a brand called bubbies . Good stuff, but about 14$ per jar.
Got me some Bubbies. And this Kimchi, finally found it. Lol