The researchers, all South Korean, report that kimchi and other spicy and fermented foods could be linked to the most common cancer among Koreans. Rates of gastric cancer among Koreans and Japanese are 10 times higher than in the United States.
"We found that if you were a very, very heavy eater of kimchi, you had a 50% higher risk of getting stomach cancer," said Kim Heon of the department of preventive medicine at Chungbuk National University and one of the authors. "It is not that kimchi is not a healthy food — it is a healthy food, but in excessive quantities there are risk factors."
It could be that the danger of kimchi might be from the large amount of salt in it, "which could combine with red pepper to form a carcinogen."
In any case, I'm not going to stop making sauerkraut. I don't use much salt when I make it anyway. Link