From one scientist to another, this is not "mumbo-jumbo". If it is working for you, don't stop.
The Kefir culture removes the lactose in milk and in doing so produces the "gut friendly" bacteria found in Yakult and the like.
The health of your gut bacteria is critical to good health, as is becoming increasingly recognised by medics.
There are a number of other pro-biotic foods, including kimchee and sauerkraut.
And talking of gut health...(not for the sensitive...)
https://en.wikipedia.org/wiki/Fecal_microbiota_transplant 
