Doctor's Note

Please feel free to post any ask-the-doctor type questions here in the comments section and I’d be happy to try to answer them. And check out the other videos on kimchi. Also, there are 1,686 other subjects covered in the rest of my videos--please feel free to explore them as well!

For some context, please check out my associated blog posts: Soymilk: shake it up! and Breast Cancer and Diet.

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  • aeason

    Is there more information about this? Is this traditionally made kimchee rather than kimchee made in a manner similar to that of making sauerkraut? For that matter what about sauerkraut and other pickles?

    • Michael Greger M.D.

      This was for traditional kimchi. I can’t find anything in the literature about sauerkraut either way, but I’ll definitely keep an eye out. It is high in sodium, so if you do eat it I would suggest moderating your intake.

      • TobiasBrown

        Would really like to learn more about sauerkraut, as it’s a very tasty way to enjoy cabbage. The delicious Spreewald brand (“mild” version) shows 480 mg sodium for a 125 gram serving. Is this really bad?

        I imagine there are lower salt options out there for this food…

      • TobiasBrown

        Dr. Weil’s website Q & A Library area has a positive review of this food yet warns about the salt levels. Guess I’ll need to look into making my own. :)

      • Rosemary Guy

        Most kimchi has a fish sauce added to it…..This may be a contiributing factor to this research. As a vegetarian who thinks garlic is smelly and aweful, I make my own and hope that the jury is still out over vegetarian kimchi

  • Eric Needs

    This is a shame.

    • Michael Greger M.D.

      My thoughts exactly–used to eat the stuff all the time!

  • Lachicavegana Comefrutas

    Hm……made with Organic Cabbages?? I wonder why?? Please find evidence and reverse this decision :)

    • Michael Greger M.D.

      This is on my pubmed alert list.

  • Deer

    Hi Dr. Greger, Can you please site where you found this information precisely? Are they talking about kimchi/fermented foods made with white vinegar? Or are they made with salt and other spices? I looked up PubMed and I am having trouble finding and understanding it as I am not learned in medical/scientific facts. thanks!

    • Michael Greger M.D.

      I’m so glad you asked! If you look on this page, right under the video you’ll see a section called Sources Cited. If you click, it will open up and list the hyperlinked citations to all the sources I use for any of the videos on the site.That is something I feel very strongly about. Nutrition information (and everything else in medicine!) should be based on the best available science. Thank you for giving me a chance to point out this feature of for those that might have missed it.

  • VegeMarian

    Looking at the abstract for the first study on breast cancer, they only controlled for non-dietary risk factors and vegetable intake. What if those who eat more kimchi also eat more preserved meats? It seems they wouldn’t have caught preserved meats as an independent risk factor in that study. I think the second study found a correlation between prostate cancer risk and all fermented foods. I don’t like to see fermented soy products included here, too! I’m going to hope salt is a culprit, and I’ll keeping eating my tempeh….

  • Mary Jurmain

    Doesn’t traditional kimchi also contain fermented fish? Could this have affected the results? I am confused: I thought fermented vegetables were really good for the immune system and for fighting cancer. I have cancer, so I really need to know whether to eat them or not.

  • Mary Jurmain

    Hi “Toxins” (hmm!? Interesting nickname!)

    Thanks for the references, which I will definitely watch again, but I already own and have watched all of Dr. Gregor’s videos, so chances are I have seen all of those clips. I know a fair amount about what I need to eat; I just want to have a very good reason if I’m going to eliminate something else from an already rather restrictive diet (and also before I throw away 30 quarts of fermented green tomatoes). I seem to recall reading something about a study that showed sauerkraut prevented H1N1 from spreading in chickens, or something similarly bizarre. I’ve read Sandor Katz’s book “Wild Fermentation”, in which he talks about how his diet, heavy on fermented foods, has kept him healthy for years in spite of AIDS. And fermented vegetables have a long tradition in many cultures. It’s not that I can’t be convinced that they’re unhealthy, but if I’m going to accept data that goes against the grain of thousands of years of human history and a fair amount of anecdotal data, I’d like more than one study to convince me; I’d like multiple studies and an explanation of the mechanism by which these foods do harm. I hope Dr. Gregor will weigh in on this debate.

  • pk

    First of all, a big thanks to you ,Dr. Greger, for providing us with this fascinating website. I love it and check it frequently.
    I was very sad to hear your report of the research regarding Kimchi. Kimchi is made with cabbage, garlic and hot peppers. It sounds like it couldn’t be healthier! What aspect of it might contribute to cancer risk?
    Is occasional eating of canned saurkraut (a few Tbs once or twice weekly), made with cabbage , salt and maybe vinegar probably unwise?

    Also: I typically prepare a salad once a week, such as cucumber salad (made with onions, dill, cucumbers, salt, lemon juice,two packets of stevia, and a little olive oil). Then I eat a little bit each day with fresh lettuce, peppers etc. Do you think this unhealthy because the cucumber salad is not made fresh daily? (It is the only stevia I have all week.)


  • debcasey

    I make fermented veggies with Body Ecology Culture Starter. I add no salt or vinegar to my fermented veggies. Do you know any scientific information on eating this type of fermented veggies? I do make sauerkraut with salt, but keep it raw with no vinegar.


  • tc247

    I understand for most koreans it’s not a meal unless there’s kimchee on the table.Is there a high rate of prostate cancer in Korea?

  • xxjane42oxx

    well Dr i am ashamed that u call yourself a doctor and dont do all your research like most doctors.. Traditionally prepared kimchi is made from raw cabbage and when fermented properly contains PROBIOTICS.. u can do some google searching and find out how beneficial probiotics are for us.. as a matter of fact, human life as we know it would not exist if it was not for PROBIOTICS…The probiotics found in kimchi and other naturally fermented vegetables ( sauerkraut, pickles, etc.) create by-products like organic acids (helps to preserve veggies and has alkalizing effects on the body) and more enzyme content (easier to digest and better absorption of nutrients).

    • Toxins

      Most doctors don’t do any research nor do most doctors care for the subject of diet! Nobody here is doubting the benefits of intestinal flora. Dr. Greger has two cited sources showing that pickling food has a negative impact on our health, could you please cite some sources that show otherwise?

    • gallifreygirl2007

      THANK YOU JANE! my exact thoughts as well!

    • Joel Santos

      Hi dr greger what do you think about gochujang?

  • xxjane42oxx

    PLUS! Fermented foods, have been used thru the ages to prevent and sometimes even cure illness. For example, sauerkraut was used by the Germans and Europeans to prevent scurvy… Due to its high concentrations of Vitamin C it helps warn off illnesses like scurvy.

    • Toxins

      Vitamin c is abundant in the plant world and eating a fermented food is not necessary to acquire this easily available nutrient.

    • Lew Payne

      xxjane42xx – please cite your sources, rather than just spout conjecture.  If you’ll notice, the information presented in the video is attributed to specific scientific studies.  What is your information based on?

  • dm47

    My wife is Korean and her family, ancestors, and everyone I know have been eating Kimchi for ages……not one of them has ever had breast cancer. I think you should search and find out more information. I couldn’t find any sources to support the video which he stated.

    • Michael Greger M.D.

       If you click on the Sources Cited link up above you’ll find the sources linked there.

  • Emmanuel Jayson Varsovia

    *ahem* “The mechanism of deleterious effects of preserved foods remains unclear”. i need to see why and how kimchi can cause an increased chance of cancer.. then ill believe the video. and doesnt one of youre sources claim that cancer is reported to be lower in asian countries than it is in western countries?

    • mike

      There are a number of studies that have found potential mechanisms (e.g. mutagenic substances produced via fermentation, there just haven’t been the studies, animal studies/clinical trials etc, to determine this for sure).

      Nitrite and secondary amines are formed with fermentation:

      1. Nan HM, Park JW, Song YJ, Yun HY, Park JS, et al.: Kimchi and soybean pastes are risk factors of gastric cancer. World J Gastroenterol 11, 3175–3181, 2005

      2. Seel DJ, Kawabata T, Nakamura M, Ishibashi T, Hamano M, et al.: N-nitroso compounds in two nitrosated food products in southwest Korea. Food Chem Toxicol 32, 1117–1123, 1994

      3. Mitacek EJ, Brunnemann KD, Suttajit M, Martin N, Limsila T, et al.:
      Exposure to N-nitroso compounds in a population of high liver cancer
      regions in Thailand: volatile nitrosamine (VNA) levels in Thai food. Food Chem Toxicol 37, 297–305, 1999.

      4. Yuan Z and Ding Y: Mutagenesis and anti-mutagenicity in several traditional Zhejiang preserved foods. Carcinogen TeratogenMutagen 15, 91–93, 2003.

      … there are also many studies about the risks of salt and the nutritional deterioration of acid-preserved foods. Many of these studies also control for confounding variables which explain the lower overall cancer rates in Asian countries.

      Dr Greger’s recommendations are based on risk-aversion

  • John Duda

    I think it might be premature to suggest eliminating all pickled vegetables from your diet based on these two studies, and a cursory review of the literature which indeed provides further evidence for an increased risk of esophageal, gastric and other cancers. Most studies having been done in Asia on relatively small numbers of subjects where the average consumption of pickled vegetables is high may have produced results that would not be seen elsewhere. Indeed, the prostate study demonstrates higher likelihood of getting prostate cancer in those eating the highest quartile of pickled vegetables, which is well above what I believe would be the norm for most Americans, with no suggestion of a dose response curve. Therefore, it might be more appropriate to suggest avoiding high intake levels of pickled vegetables and admit that we don’t have enough data to determine the effect of lower levels of intake. However, I agree that until health benefits of pickled vegetables are proven, they should not contribute a large percentage of vegetable consumption.

  • Michael Greger M.D.

    Also be sure to check out my associated blog post Breast Cancer and Diet!

  • Dana Razzano

    I was wondering if you had any information on capers? The kind you find pickled in jars. I’ve heard the berry is high in antioxidants but then I only see them sold pickled, and it seems that this might not be a good thing. Thanks for all of your hard work!!

  • Easter Cat

    I couldn’t read the Yu study, so I didn’t know if they differentiated between vegan and non-vegan (e.g., shrimp paste, anchovy, fish paste); traditional kimchi in Korea isn’t vegan.

    As a vegan who has finally found a source of vegan kimchi, this information–if true–makes me sad.

  • D504
  • D504

    kinda conflicts with mainstream theories of whether it healthy? 

  • Bee

    I thought that eating fermented foods helps with dysbiosis?  Are the raw/salt-free sauerkrauts ok to eat (like Rejuvenative Foods brand)?

  • Marty

    I checked out this site and it says that Korea had low prostate cancer rates but
    as they become more westernized their rates are increasing.

    This comparison of prostate cancer death rate by country

    lists the U.S.
    is 103 whereas South Korea, the birthplace of kimchi, is low at 165.
    I look forward to learning more on this because I make my own kimchi and I love it.

  • Ted

    Seems like some studies are schlock-Fermented and organic foods are still healthy to consume. I sometimes really question the surdies you accept as fact…

  • Chan J Jong

    Jesus Christ. Is is so bad? I think this biased video forgot to mention that Kimchi is rich in vitamin A, thiamine (B1), riboflavin (B2), calcium, and iron,[15][16] and contains a number of lactic acid bacteria, among those the typical species Lactobacillus kimchii.[17][18][19] Health magazine named kimchi in its list of top five “World’s Healthiest Foods” for being rich in vitamins, aiding digestion, and even possibly reducing cancer growth.[20]
    If anything, Just look at the difference between the obesity levels between USA and Korea ._.

  • ….

    I don’t know where you found the information or the idea that kimchi increases the probability of breast cancer. Neither do I know how familiar you are with the food itself. But i do want to point out to you that first of all, Koreans have been eating kimchi for centuries; however, studies have shown that only recently (since the early 1990s) have breast cancer incidents been steadily increasing. If Koreans have been eating kimchi for centuries, why should this problem start arising now? Maybe instead of targeting kimchi specifically, look at the broader picture and trends. For example, did you know that the increase in cancer incidents coincides with the timing that Western diets were introduced to Korea? Moreover, not only breast cancer but cancer rates in general has increased in Korea after the introduction of Western Diet. And something else i think you should know. According to breast cancer statistics in Korea, despite the increase of breast cancer incidents, Korea still has lower breast cancer incidents (26.2 per 10000) compared to the world average of 37.4 per 100000.

  • Dan A

    I think Dr Greger does us a great service by informing us of the latest dietary research. However quickly leaping to conclusions and giving broad recommendations based on insufficient research, or a very narrow interpretation of that research is a big problem in what he does, it discredits everything he says, and this video is a perfect case in point.

    Based on two small Korean studies, he’s telling people to never eat Kimchi because he thinks it will cause cancer. I looked at the studies and they do not seem tightly controlled or conclusive at all, and have no mechanism proposed (as others have pointed out).

    I am increasingly taking all of Dr Greger’s recommendations with a grain of salt (and in this case, a lot of salt, along with some fermented vinegar..)

  • gallifreygirl2007


    • gallifreygirl2007

      World’s Healthiest Foods: Kimchi (Korea)

  • rachel

    I tend to believe there are additional factors involved besides people
    consuming more pickled vegetables. Perhaps the people consuming them made them in a certain way that created scum or mold? or with certain ingredients like fish, contaminated seaweed, dairy? I do not know these specifics.
    I DO know that I am a vegetarian/vegan for 25 years who has fallen in love with healthy fermented vegetables including sauerkraut and Kimchi (which i make myself). Why do I mention “healthy”? because what most people do, and is “tradition”, is to use a german or polish type ceramic pickling crock. These may be traditional but they usually allow air in them which creates scum or mold and people think it is healthy and beneficial to simply “skim off” the scum or mold and the rest is healthy to eat (yuk). What they are making is “rotten” vegetables. Healthy “Fermented” vegetables should have no foul odor that smells rotten.
    I use a fermenting vessel that is fool proof if you follow directions
    carefully. The is made of glass and it keeps the
    air out. namaste;, rachel

  • bernard

    Don’t believe everything you hear on the internet, there are so many disinformation out there.

    Kimchi and other fermented vegetables contains essential probiotics which everybody nowadays (in chemical loaded environment) are lacking of.

    However on the opposite side, fermented vegetables contains Acetaldehyde compound which can be detrimental to our health if consumed in large quantity. Therefore Fermented food is a double edge-sword, it is good to our health if consumed in moderation, but bad if we overconsumed.

    The notion of Kimchi is bad overall and must be avoided is ludicrous, our ancestors had been fermenting vegetables for thousands of years before the invention of refrigerator. How else can they eat their vege during winter months?

    If Kimchi is bad overall, one must question, “how to these Koreans, survived 2000 years of Kimchi without dropping dead all over from Breast Cancer!????”

  • Tomek

    And what would you say about this article: ?

  • Tomek

    However, I think it’s a great source of information, but it may be that some fermented veggies (especially Kimchi) would have a very different risk associations with the cancers and other health issues, depending on the context of the study as there are a lot of cancer types. I mean that according to some research they can slow or even inhibit some types of cancer, on the contrary, other research may prove that it’s completely different with other cancers.

  • michelleden

    This seems to directly oppose your conclusions and is very indepth study. Better than some of the studies you cited, in fact… It’s google-able.

    Dietary factors and gastric cancer in Korea: A case-control study

    Hyun Ja Kim1, Woong Ki Chang2, Mi Kyung Kim1, Sang Sun Lee3, Bo Youl Choi1,†,*

    Article first published online: 2 NOV 2001

    DOI: 10.1002/ijc.10111

  • Christie
  • Planteater

    Not all fermented foods are pickled and not all pickles are fermented. If you buy kimche in a jar, it may not have been fermented (no probiotics), may have been pasteurized (no probiotics), and will probably have preservatives. I wish this study had made fermented kimche to compare to the store bought.

    • planteater

      Go to the grocer and try to find a jar of pickles, kimche or sauerkraut that is also fermented and doesn’t have preservatives. It’s nearly impossible. These studies did NOT look at traditional kimche because it was not fermented. If you want to look at benefits of true fermented veggies, it would be best to disregard this study because it only looks at preserved foods. Who wants to eat that?!

      • DanielFaster

        I’m reposting a comment from another thread since I agree with you and think the topic is treated too superficially on this site – I’d really like to see it explored a bit more:
        I’m keen on fermented plant-based foods like miso, natto, amazake, kombucha, homebrew beer and lacto-fermented veggies – I think it may be a bit oversimplistic to lump all these together, see http://kimchicancer.blogspot.c… which notes a protective effect for some fermentates and a cancer increased risk with others, e.g. radishes.

    • Char Covelesky

      Fact is, once a fermented food is jarred or canned under heat, the probiotics are killed and it it is worthless as a source of them, preservatives or not. Also, I think it needs to be reiterated that “pickling” can refer to simply adding vinegar to ingredients, again, rendering a food worthless as a source of probiotics! Cultured, lacto-fermented vegetables indeed have a long and illustrious history and regardless of what a few recent questionable studies show, I’ve been consuming them for my 60+ years and will continue to, especially in light of the newish volumes of info (and LOTS of personal experience) regarding the importance of the microbes in our gut as our “second brain”. Like anything else, be moderate, a good overall diet is the most important thing!

  • Jennifer

    Sad face! I love kimchi, assumed since it was cabbage with spices that it would be good for you. :(

  • Sarah Elaine Gallagher Layton
    • JacquieRN

      Not enough said for me. The article you linked to is simply a reminder of how easy it is to attack another person on the web. It is one thing to disagree and present scientific evidence but it is another thing to call people names and just slam other well meaning organizations that do base their work on research with significant improvement in people’s lives. Even the Harriet Hall in her article linked to at Science-Based Medicine has “cherry picked”, didn’t stick to facts, used gross generalizations, omissions when citing a study and veered off from scientific objectivity. Would Harriet Hall MD actually speak to Michael Greger MD, C. Esselstyn MD, Neal Barnard MD, Dean Ornish MD, John McDougall MD, etc. that way or tone – I can bet not.

  • Adrian Hansen

    The causes of cancer are still a mystery, so just take this ‘research’ with a ‘grain of salt ‘ !

  • vegan minstrel

    Wondering if the chile pepper ingredient could be a factor. Though it’s been shown to have anti-cancer properties, a 2010 study showed capsaicin to be carcinogenic for skin cancer:

    As for sauerkraut, anyone concerned about it having too much sodium can make their own with potassium chloride.

  • James N

    I wonder if the fish content of kimchi has anything to do with the formation of carcinogens. I just made a huge batch of vegan kimchi and wonder if I should throw it out now. I wish I had found this video first!

    • Char Covelesky

      Don’t throw it out! People have been eating this for thousands of years! There may be more to these studies than meets the eye or else it would have been apparent long ago! Seriously, think about it! Even too much water can kill you! Relax…it’s a condiment, not a daily meal!

  • Cheryl

    This would suggest that non-preserved fermented foods can provide beneficial bacteria, without increasing cancer risk. Kombucha is too risky, how about vegan yogurt or kefir? There is evidence for the benefit of fermented food, but now against preservation. Perhaps due to salt or acidity?

  • Eric Salisbury

    “what can’t we eat now?”, “why is there parsley in everything all of a sudden?” ROTFL! *Good healthy laughs* :)

  • Joel Santos

    Hi dr greger. Are there any studies on gochujang? Is it okay to still use it?