Kvass (Probiotic Beverage)


Kvass is a delightful traditional Slavic fermented drink. Originally it was made with bread, but fruit varieties are now most popular because they are especially appealing for children. In my book, Fuck Portion Control I talk about how most probiotic products are not helpful and sometimes even harmful because they are usually made of strains which are chosen for their hardiness through the distribution and packaging process and not because they are especially healthful. Contrary to popular belief, commercial yogurt can actually be quite harmful, because the sheer amount of lactic acid combined with aggressive lactic acid producers like Lactobacillus delbrueckii can effectively suppress populations of other bacteria which produce our important short chain fatty acids and permanently shift the microbiological composition of the gut, and large amounts of lactic acid can and do lower the metabolic rate. Kvass is a gentler probiotic that can be compared more to living bread, using common active yeast to gently ferment fruit and sugar and makes large amounts of B vitamins and fizzy carbonation. Active yeast is typically the strain Saccharomyces cerevisiae which is shown in studies to directly attack and inactivate harmful pathogens such as Candida. In fact, this beverage can be used to help support the gut microbiome. Plus, it’s downright delicious. This photo is of Berry Kvass, but my favorite is Nectarine. Any fruit can be used, as the point of using this is merely to deliver active, viable yeast and B vitamins. In the summertime you may want to brew a giant cooler of this, it’s so good and will go very fast, but make sure to never seal the container and to stir it daily as any yeast which consumes all the oxygen in the batch will begin to produce alcohol, and for that reason it’s best to use up within a few days. Don’t store longer than a week. DO NOT MIX IN A SEALED CONTAINER. IT WILL EXPLODE AND CAN INJURE YOU OR OTHERS.


1 pint non-chlorinated water
1 cup organic unrefined sugar
1-2 cups fruit of your choosing (berries, peaches, nectarines, etc.)
1 tsp active yeast or starter

In a large container (do not seal as this can explode) add water, yeast, and sugar. Stir until dissolved. Cut or smash fruit and add to container. Cover but do not tightly seal. Allow to ferment in a warm spot for 8 hours. Typically Kvass is enjoyed after several days of fermenting, but to get more yeast probiotic benefit it’s better to drink it after 8-10 hours and before two or three days. You should see robust carbonation rising in the drink and that indicates it’s ready. If you ferment it for very long the yeast may consume all the sugar and you might want to add more if it doesn’t taste sweet. Serve with or without fruit as you desire. Do not store indefinitely as it will eventually become dominated by bacteria.