Here’s an easy way to add both probiotics and prebiotics to your life: Fermented raw potatoes. The mildly tangy flavor of these fermented raw potatoes go well tossed into a salad, though you can just eat them right out of the jar, too.
Because they are raw, there are zero net carbs but plenty of fiber. (When heated, however, fibers depolymerize or break down into sugars. When raw and unheated, fibers remain in polymer form.) Raw potatoes therefore provide you with prebiotic fibers to nourish bowel flora.
When you lactate-ferment these raw potatoes, you also cultivate beneficial bacterial species such as Lactobacillus, Bifidobacteria, Leuconostoc species and others that add to healthy bowel flora.
Fermented raw potatoes are therefore an easy and convenient way to add both more probiotic species and prebiotic fibers. I found potatoes to be easier to ferment than most other veggies, as the potatoes, chopped into half-inch (one centimeter) cubes, sunk to the bottom of the jar, thereby not requiring any device to weigh them down to keep them below the air-water interface. (Recall that lactic acid fermentation is an anaerobic process and is inhibited by the presence of oxygen. Veggies must therefore be kept below the air-water interface. The dense cubes of potatoes accomplished this all on their own.)
The recipe is very simple, but there are some reminders to make sure that fermentation can proceed. First, use filtered or distilled water, as tap water that contains chlorine or fluoride will block fermentation. Likewise, when making the brine solution, do not use iodized salt, as iodine will block fermentation, also. (I have used sea salt many times with success.)
To make fermented raw potatoes, place approximately 4 cups of filtered water into a jar, followed by enough salt to generate the level of saltiness you desire (e.g., 1 tablespoon).
Chop potatoes (unpeeled; if any green tinge is present on the skin, remove) into half-inch cubes, then add to water. Cover with paper towel, cheesecloth, or other non-air-tight device.
You will see the water turn cloudy over the next 48 hours, along with tiny bubbles, all reflecting the process of fermentation. If any white film appears on top, remove with a spoon and discard. When the water is moderately cloudy and potatoes have that lactic acid “zing,” transfer jar to refrigerator. Consume within the next week.