When I was growing up on the farm, May was sauerkraut month. Farm women would gather heads of cabbage from their gardens, shred them, add salt and water, and ferment them in huge vats wafting odors that literally could be smelled for a mile. My mother used to tell me some of our neighbors stomped vats of shredded cabbage with their feet to provide the right bacteria for fermentation, but I never personally witnessed this.
Although sauerkraut, literally “sour cabbage,” is thought of as a German Kraut cannot be made sour with soaking the cabbage in brine, so the finished product is always high in salt. Souring cabbage concentrates potentially carcinogenic nitrites in the early stages of picking, but these disappear within thirty days (and they can be washed out of the kraut that is eaten before it is pickled). It does not reduce vitamin content; in some cases, depending on the exact strain of bacteria fermenting the cabbage, krauting increases the vitamin content of the cabbage.
Like other foods made from vegetables in the cabbage family, kraut contains the sulfur-bearing compounds known as isothiocyanates, but the sulfur in kraut fights infection rather than cancer. Specifically, really sour sauerkraut is especially potent against the foodborne infectious microorganism Listeria.