Fermented Foods and Vitamin B12

Someone sent me this question below and I thought I’d clear it up for anyone else who is wondering:

You did not mention kimchee or sauerkraut in your list of erroneous sources of B12. I wonder if you have any information about these products.

To my knowledge, there is no fermented food that requires a B12-producing bacteria for its fermentation. Wherever there are large amounts of bacteria, the chances increase that some B12-producing bacteria could be in the mix. Although the chances might increase, it is still unlikely, especially where fecal contamination is not involved, that a food is going to have biologically significant amounts of vitamin B12. But I have not seen any studies on kimchee or sauerkraut.

19 Responses to “Fermented Foods and Vitamin B12”

  1. Dave Says:

    A little off topic since this isnt about B12, but I’m so happy to hear that more soy research reporting is on your list, Jack. I still have so many questions about soy.

    For example, people seem to just lump all soy products together as equally healthy (or unhealthy, as the case may be). I would love to learn more about the various forms of soy and which are most healthy and which are better to avoid. For example, we try to avoid isolate and consume more whole soy, particularly fermented forms like tempeh. Is it true that isolates are particularly high in goitrogens compared to other forms?

    And as far as soy milk is concerned, all they all equal? Particularly regarding trypsin inhibitors and phytic acid. Can we assume that manufacturers process the milk in such a way to minimize these substances? Unfortunately, this is not the kind of info you’d find on a nutrition label.

    Should aluminum contamination be something that soy eaters concern themselves with, particularly in isolate form? I have no idea how common it is across the industry. (An aside: I wrote Turtle Island Foods last year — they use no isolates, btw — and confirmed they use no aluminum tanks, vats, etc., in their food production.)

    I’ll have to dig up my other soy questions that I’ve been jotting down over the last few years…..anyway, thanks as always for your great work.

  2. Jack Norris RD Says:

    Hi Dave,

    I don’t think there’s enough research to be able to answer most of your questions with any satisfaction, unfortunately. Have you tried to find out how much phytic acid is in soymilk? I’d probably just start at Google. Probably less info on trypsin inhibitors though my understanding is that cooking would destroy them and soymilk is made from cooked soybeans. For what it’s worth:


  3. Tamar Says:

    Can’t wait for the soy article!

  4. Dave Says:

    Thanks for the link.

    Check this one out, too, by Eden Foods. Their FAQ, in fact, generated many of my soy questions, particularly if other companies are also “doing it right”, or if Eden is ahead of the curve:


    I guess they reduce phytic acid not only by cooking but also by removing the hull and using a “patented enzyme invalidator!?”

    It looks like they reduce trypsin in much the same way: dehulling, cooking, enzyme deactivator.

    Anyway, I guess the only way to really way to answer some of these questions is to ask each company individually and/or have third party testing of products for Al content, etc. And lots of Googling, as you said.

    With isolate becoming so prevalant, I guess that will be the main thing I will try track down: whether it’s really as bad a form as the Eden faq would lead one to believe. And the whole thing on genistein, too. I need to read up on that.

    As far as the phytoestrogen-related complaints, I think that’s been disproven to be a problem (?) and Dr. Greger had an insightful comment in his last batch of DVDs pointing out the irony that dairy milk in fact has ACTUAL estrogen in it, now that so many dairy cows are pregnant while producing commercial milk.

    Bottom line, I love soy products, but I’m still paranoid about them!

  5. Jack Norris RD Says:


    I don’t have time to read that carefully right now, but I will before putting out my piece.

  6. rick Says:

    Regarding the b12 bacteria please, in addition to the necessity for their presence, is not the presence of cobalt also necessary to enable b12 production? In other words, are the bacteria able to produce b12 without a source of cobalt?


  7. Jack Norris RD Says:


    Cobalt is necessary.

  8. Colinski Says:

    Jack, I hope this isn’t too off-topic, but I’m reminded that I need to order another bottle of B12 soon, and most vegan B12 supplements I’m looking at are Methylcobalamin. Your recommendations, although not explicitly pointed out on the recommendations page on veganhealth, seem to be for cyanocobalamin, and there seems to be some research buried on other pages in your expansive B12 section suggesting that one should take more higher dosages than recommended for cyanocobalamin if supplementing with methylcobalamin. However, I can’t seem to find specific recommendations for a maintenance dose of methylcobalamin on your site.

    I have been taking a 1000mcg methylcobalamin B12 supplement twice a week, starting almost a year ago (after going vegan maybe 6-9 months before that). I had a blood test about 6 months ago, revealing no B12 deficiency. However, I noticed the section on methylcobalamin on veganhealth a couple months ago and upped my dose to 3x a week to be safe. Do you think that is sufficient? Should I take more? Or am I better off tracking down a cyanocobalamin supplement?

  9. Jack Norris RD Says:


    Based on one small study of 3 people, that’s probably not enough. I would take 1,000 mcg daily if you are going to rely on methylcobalamin. I don’t have an opinion on whether you should switch to cyano-, but most natural food stores and drug stores carry cyano- (in the U.S.). Cyano- has been tested a lot more, so I know the dosage amounts. At small doses, cyano- is better.

  10. Colinski Says:

    Gotcha. So, if I got a 1000mcg cyanocobalamin supplement, taking it twice a week is appropriate?

  11. Jack Norris RD Says:


  12. Betty Says:

    A member of my household takes a B-12 supplement in liquid form containing 3 kinds of B-12: Cyanocobalamin, Methylcobalamin, & Dibencozide.

  13. Pia Esposito Says:

    Jack, I am a lifetime vegetarian and since 2 years vegan. I am taking 1000mcg
    of B12 cyanocobalamin under the tongue daily.Is that too much for a 80 year old?
    Thanks for your reply, Pia E.

  14. Jack Norris RD Says:


    I’m unaware of people in their 80s needing different amounts of B12 than younger adults, or not being able to tolerate as much. I recommend 1,000 mcg twice per week. You probably don’t need to take it every day but maybe every other day wouldn’t hurt.


  15. Steve Jones Says:

    I thought you’d like to know that I tried eating all sorts of vegan foods that are supposed to have B12, but when tested, my levels were still low. I then took 100mg of B12 for about 6 months and my levels had risen a bit bit not much. It wasn’t until I found a doctor who advised me to take 5000mg mcg per day of B12 that my levels started to improve.

    You should be careful about having debates about what contains B12 and what doesn’t. Even if foods contain it (which we can’t be sure of), our bodies may need much larger amounts. Many people don’t absorb B12, so even if you are are getting in in your food it may be useless.

    The only way to find out what’s good for you as an individual is to get tested. There is no point think or hoping that you are ok. That’s what I did for decades. It just doesn’t work and can end up ruining your health. Luckily I’m ok.

  16. Jack Norris RD Says:


    Thanks for the info. 1 out of 50 people cannot absorb vitamin B12. If you suspect you are such a person, then you should get your B12 levels tested (relatively soon). I don’t think other people need to worry about it, although if you are going to get tested for other things, adding B12 would be a good idea.

  17. Lady Says:

    Jack , what do you think is that right? —>

    “Cyanocobalamin is in every vitamin B12 supplement known because it is stable and less costly to manufacture. But it is not usable in the body. If the body has sufficient energy it may be able to offload the cyanide and benefit from the useful component. Mainly, what people experience after taking cyanocobalamin supplements is stimulation. The toxic effect of the cyanide triggers a rush of energy as the body works hard to excrete the poison, and this fools people into believing that the supplement has “worked” to heal them. Meanwhile, if their blood tests show an increase in B12, it mainly reflects the amount of the CYANOCOBALAMIN in the blood stream. The usable forms are carried into the cells and can’t be discovered by testing the blood as is the current practice. Blood tests are often inaccurate and, as previously stated, in the case of cyanocobalamin supplementation and B12 injections, about 90% of it has been eliminated from the body in 24 hours.”

    founding here: http://www.roylretreat.com/articles/b12.html

  18. Jack Norris RD Says:


    No, I do not think that is right. Dr. Vetrano’s ideas are pretty fanciful.

  19. Lady Says:

    Yes, sorry. I didn`t notice that you`ve already wrote about this in an extra entry ;))
    Thank you for all the infos on your blog and on veganhealth.org. Try to move it on to more readers 😉

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