Thomas: I wouldn’t worry about that, kefir contains probiotics which is a good thing. However if you feed the candida with sugar, bad foods, etc, the flora in your gut won’t thrive as good as possible.
wishnhope: You don’t have to put the store made stuff through a strainer. I don’t know if you can buy grains at your store, most stores don’t have them. There is kefir starting kits which are more common at stores. The milk ferments so it doesnt go bad unless you leave it out too long (for more than 3 days). Making homemade kefir is a little tricky because your household temperature has to be above 70 degrees F. I tried to make kefir and it didn’t come out good at all.
The store bought pre-made stuff should look like a mixture between milk and yogurt. You can drink it straight, add it to yogurt, whatever you want.