Sauerkraut is a fermented food. Fermentation is the metabolic process of converting carbohydrates, like sugars, into either alcohols and carbon dioxide, or organic acids. It requires the presence of a carbohydrate source (like milk or vegetables, which contain sugar molecules) plus yeast, bacteria or both. The yeast and bacteria microorganisms are responsible for converting glucose (sugar) into healthy bacteria strains that populate your gut environment and help regulate many bodily functions.
Sauerkraut’s live and active probiotics have beneficial effects on the health of your digestive tract — and therefore the rest of your body too. That’s because a very large portion of your immune system actually lives within your gut and is run by bacterial organisms, what you can think of as “your gut’s bugs” that live within your intestinal flora.
After eating foods like sauerkraut that provide probiotics, these gut bugs take up residence on the lining and folds of your intestinal walls, where they communicate with your brain via the vagus nerve. They also act like your first line of defense against various harmful bacteria or toxins that enter your body. Some beneficial probiotic bacteria found in sauerkraut and other cultured veggies are more or less permanent residents because they form long-lasting colonies.