You can find out all the health benefits Kefirhere.
We were fortunate enough to be given some granuales to grow. You can buy granules off the Internet and grow your own. Getting a good source of water is essential. It does take time and effort, but is very educational for children, a science experiment to drink!
We find, that if we do fall ill with a tummy bug, pre-made shop kefir is a lovely way to calm the stomach down.
I do hope you have the opportunity to carry out this natural experiment.