Sauerkraut contains large nitrite, which is easily converted into nitrosamines and other nitroso compounds in the stomach (or outside the body), thus having a clear carcinogenic effect on gastric cancer, esophageal cancer, and liver cancer. etc. have made outstanding contributions. When talking about the causes of cancer, textbooks on cancer, large and small, generally mention the role of sauerkraut. Large-scale international research conducted in Lin County, Henan in the 1980s and 1990s has fully confirmed this point. During the pickling process, sauerkraut is easily contaminated by microorganisms, which reduces it to nitrite. Eating sauerkraut containing too much nitrite will turn the hemoglobin in the blood into methemoglobin, which loses its oxygen-carrying function. Everyone knows that people cannot live without oxygen for a moment. Once oxygen is deprived, symptoms of hypoxia will appear throughout the body. People's skin and lips will turn purple, accompanied by poisoning symptoms such as headache, dizziness, nausea, vomiting, and palpitation. Severe cases can lead to death. In addition, during the pickling process, sauerkraut will also produce carcinogenic nitrite compounds, which can easily induce cancer. Especially moldy sauerkraut has a more obvious carcinogenic effect.

According to the relevant national regulations on the declaration of pickled vegetables as green food, the nitrite content in sauerkraut should be 4 mg per kilogram, which is the weight of half a millet grain. If you eat twenty or thirty millet grains, so much nitrite can cause poisoning.

Eating a lot of sauerkraut can easily lead to the formation of stones. Pickled sauerkraut contains a lot of oxalic acid and calcium. Due to the high acidity, calcium oxalate is not easily formed in the intestines and excreted after consumption, but is absorbed in large quantities. When excreted by the kidneys, calcium oxalate is produced that is difficult to dissolve and absorb, thus forming stones. In addition, during the process of pickling sauerkraut, vitamin C is greatly destroyed. If the human body lacks vitamin C, it will reduce the ability to inhibit the deposition of calcium oxalate crystals in the kidney and reduce the formation of stones, which is also a factor in the formation of stones.

When eating sauerkraut, it is best to eat foods rich in vitamin C, such as peppers, cauliflower, coriander, garlic sprouts, mustard greens, bitter gourd, mustard greens, etc. among vegetables; fresh oranges, grapefruits, and fresh dates among fruits , hawthorn, cherry, kiwi, strawberry, etc. This is because vitamin C can react with nitrite to prevent the formation of carcinogens; vitamin C can also be taken orally before or after meals. Sauerkraut will inevitably produce nitrite during the pickling process. If the nitrite content in 1 kilogram of sauerkraut exceeds 150 mg, it will cause poisoning.