Kimchi is not recommended for breast cancer
Kimchi is a Korean condiment made primarily from Chinese cabbage (bok choy) fermented by lactic acid bacteria (while there are other types of kimchi, the findings presented here refer to cabbage kimchi). Cabbage has been shown to have chemopreventive actions against a wide variety of cancers, including breast cancer. However, the method of preparation of kimchi and its other ingredients appears to result in a food that lacks some of the anticarcinogenic attributes of Chinese cabbage and may, in fact, support cancer proliferation.
Cancer-related effects of eating kimchi
Kimchi has been found to prevent atherosclerosis in experimental rabbits with high cholesterol and has been found to be associated with lower colorectal cancer in Koreans. However consumption of kimchi has also been associated with increased risk of gastric cancer and breast cancer in Koreans. While kimchi shares many of the chemopreventive components of cabbage, it typically contains other ingredients, such as ethyl carbamate and high levels of salt and hot red pepper, that have been shown to be carcinogenic. The effects of these substances are likely to be cumulative in conjunction with the consumption of other Korean foods with high levels of these ingredients. Therefore, it may be that regularly eating small amounts of kimchi in a diet that contains few other traditional fermented or pickled Korean foods might have little carcinogenic effect compared to eating kimchi as part of a traditional Korean diet. However, based on the limited information available, it makes sense for breast cancer patients, breast cancer survivors and those at high risk for breast cancer to limit their consumption of kimchi.
Additional comments
Note that while we are continually searching for new evidence specifically concerning this food, there is not much interest in it among breast cancer researchers, so few studies are available.