I just took a swig of Russian Rye Bread Kvass that I made this week.
Kvass is a fermented probiotic drink. It can get a bit alcoholic and you end up with a champagne-like drink. Not super sweet, kinda like 7-Up and just as refreshing.
This is not the real recipe, just giving an idea of what is involved... a cup of dry toasted rye bread crumbs. The best brand available; bottled spring water; sugar; raisins. The bread is soaked in boiled water, allowed to cool, yeast and sugar added. Refrigerate with the raisins for two days. It has to burped because it ferments really fast.
It is fun to make, delicious and healthy for the gut. There are a lot of recipes for this on the Net along with fruit and beet Kvass.