Kefir is a probiotic. It is like yogurt and contains lots of friendly bacteria which are helpful to your gut. If you have a happy gut you have a happy body. Apparently its good for dogs too. Its very easy to make, the biggest problem on keto is that you can’t be sure exactly how much sugar is in it. but as the bacteria eat the sugar,I don’t worry about it too much as I feel the benefits out weigh the carb load. and its not like you will drinking a whole pint a day, its quite a sour taste.
This is how I make kefir, using organic whole milk, some people swear by using unpasteurized raw milk for extra benefit and if you are dairy free it can be made with water or coconut milk, but as the grains need to feed off of sugar to survive you will have to add something to the non dairy options or it will die off.
If you are going away you can slow the process down by putting the grains in the fridge and the cold temperature will stop them feeding and growing.