Doctor's Note

This is the third of a five-part video series this week on Vitamin B12. For why one might choose supplements and fortified foods, see Safest Source of B12. Next, I cover various daily regimens in Daily Source of Vitamin B12. B12 is one of the few Vitamin Supplements Worth Taking.

And if you’re new to the issue, see my blog post, Vegan B12 Deficiency: Putting It into Perspective, for some background. If you’re that much of a nutri-nerd to enjoy these derivations, see my nine-part video series on vitamin D, starting with Vitamin D Recommendations Changed. If you’d rather just cut to the chase, see my Optimum Nutrition Recommendations

For more context, check out my associated blog posts: Best Nutrition Bang for Your Buck, and What Is the Healthiest Meat?

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  • Michael Greger M.D.

    This is the third of a five-part video series this week on B12. For why one might choose supplements and fortified foods see yesterday’s video of the day, Safest Source of B12. Tomorrow I’ll cover various daily regimens. B12 is one of the few Vitamin Supplements Worth Taking. And if you’re new to the issue, please see my blog post Vegan B12 Deficiency: Putting It into Perspective for some background. If you’re that much of a nutrinerd to enjoy these derivations, see my nine-part video series on vitamin D starting with Vitamin D Recommendations Changed. If you’d rather just cut to the chase, see my recommendations here. As always these are just a few of the 1,500 or so topics I have videos about.

    • Alexandre

      Dr Greger (I love you) this is actually not a question but it would be so amazing if had its own online shop with products of trust like b12, amla, hibiscus, omega 3 etc. It would be so much easier for people and the site would actually benefit naturally. even if not a shop a “recommendation page” with brands and products of trust (that could be negociated for publicity) would BE SO GREAT! Thank you

      • lilyroza

        It really helps to know that there is nothing for sale here except the information, and all that income goes back into the site to spread accurate nutrtional information. It’s a very good selling point for Dr. Greger’s videos and books and speaking tours, that there is no profit motive.

  • What does the equation look like for fortified soy or rice mik? How many cups a day provide sufficient b12?

    • Toxins

      Dr. Greger is recommending 250 mcg minimum of b12 per day. Silk original soy milk has approximately 1.2 mcg per cup serving.

      • BanGMOs108

        Unfermented soy products like soy milk, tofu, etc are not a safe food for anyone. It causes hormone imbalances, speeds aging, and lowers intelligence.

        Most Silk products are no longer certified organic and some are processed with hexane, a neurotoxin. And yet they can still be labeled “natural”. Some of their products may contain some organic ingredients, so the label “made with organic ingredients” is still used.

        • Massimo

          A troll paid by the milk & meat industry who cites Mercola, one of the most famous charlatans on the web, targeted even by FDA:

          • M Bel

            Wow, even a link to quack watch, brainwashing alive and well. Educate yourself a little.

    • Michael Greger M.D.

      The 250 a day is only if you take it in a single dose. Three servings a day of B12 fortified foods like soy milk should be finet. See the next video in the series for details: Daily Source of Vitamin B12

  • Please make this…. and EVERY VIDEO… EVERY DAY… visible on your YouTube homepage.

    Asking you to do this every day is getting very tedious.

    For many weeks this wasn’t a problem. So why now?

    • Toxins

      Mac, I think Dr. Greger wants people to visit the website, not youtube. Posting annoyingly everyday to a video is not a good approach to get your way.

      Furthermore, if people want to ask “Ask the doctor” type questions they can’t do so effectively on youtube, the comments are better controlled on

      • Hello Toxins,

        Thanks for your observations. Please allow me to clarify. I am not whining to “get my way”. I am asking for a reasonable accommodation.

        For the forseeable future, my only web access is an old Palm Centro which accesses YouTube videos by auto-launching the Kinoma player, but only at The player will not launch at

        I do not want to comment at (nor can I due to login issues).

        Funnelling comments to makes sense, and I believe the good doc has the option of closing off commenting at YT if he wants to.

        Thank you for your understanding.

        • Toxins

          I understand your predicament, I check the comments several times a day so if you happen to post a comment requesting a direct youtube link I can assist you with this.

        • hcdr

          you are pushing the boundaries of web accessibility :)

          • @ hcdr I know, I know. The march of web technology continues on unabated with or without me.

            @toxins Thanks for the link. There’s no substitute for my being able to access at the doc’s YouTube homepage,though, especially for a watching a series of related videos. Since Kinoma player won’t launch here, setting up a playlist is futile.

        • hcdr

          Also, youtube can take a while to update its feeds, I’ve noticed this with subscriptions I have. It’s nothing to do with Dr Greger… you just need to be patient, that’s all :)
          (or subscribe to email alerts)

  • Ted

    In the video “Vitamin B12 Recommendation Change,” dietary intakes of 4 to 7 ug dietary B12 were found to reduce the methylmalonic acid and homcysteine to desired levels. It seems to me then that “dietary intake” already accounts for the low absorption rate of B12, and hence I do not see why there is a need to up-adjust the recommended levels. Perhaps in the study the B12 was injected and that’s the reason for up-adjusting the recommended levels?

    • William Hiatt

      Ted , That is a hood observation and as we the cell cam only receive between 1.5 and 1.75 ug at a time resulting in dosage dumping (expensive urine) another misunderstood aspect of oral cyanocobalamin is the methylation of the toxic caynadide moles. this is an article about methylcobalamin and th reduction of Homo-cysteine levels When it comes to value a two month supply of Methylcobalamin ans the entire B complex for 20 some dollars is the best value out there I use Transdermal Patches from this site

  • Meha

    How much time it takes to receptor de-saturate? I take a 2000 pill twice a week. Is iherbs a reliable brand?

    • Toxins

      It takes 6 hours for the receptors to desaturate. Stay tuned for the next 2 videos on b12.

  • Kal

    Ted beat me to my question, I suspect the good doctor made a mistake on this one.
    A plasma concentration of 200 pmol/L is typically considered sufficient and <150 pmol/L is typically considered deficient. There is a school of thought that to protect the most people the sufficient level should be raised to 400 pmol/L with under 200 pmol/L being considered morbidly deficient.
    In the Framingham Offspring Study (a source of data for some of the cited papers) it was found that people who consumed an average of 16.3±0.8 µg B12 per day, largely from suppliments, attained an average plasma B12 level of 398.1±7.8 pmol/L.
    In that study, even people who got just 4-5 µg B12 per day from food sources typically had a plasma B12 concentration nearing 300 pmol/L, a level most modern researchers would call sufficient.

    Plasma vitamin B-12 concentrations relate to intake source in the Framingham Offspring Study:

    Its true, there are several mechanisms by which some people either do not absorb, can not use, or can not retain B12 well enough and thus manifest symptoms of deficiency and anyone with deficiency symptoms should be tested despite daily intake level, but for the majority it seems somewhere on the order of 16 µg B12 per day should be enough.

    As a strict vegetarian and the grandson of a pharmacist I have the habit of recompounding cyanocobalamin pills into a food ingredient so I can easily add 50 µg B12 into my food each day. There seems to be no harm to using too much B12 but I see no scientifically supported reason to alter my current practices.

    • Toxins


      Stay tuned for 2 more videos on vitamin b12 following this one.
      “Daily source of b12”
      “New vitamin b12 test”

      hopefully they answer your questions.

    • William Hiatt

      Kal, those are interesting studies and many think they are flawed, however an often over looked aspect is the pharmaceutical induced nutrient depletion or nutrient blocking.

  • BPCveg

    Does anyone have any leads for where you get a 20 year supply of vitamin B12 for $40?

    • rhy7s

       Just another query on where to get cheap bulk b12?

      • Anne

  • Jessica

    Vitamin B12 is an important topic, and I’m very grateful to Dr. Greger for making this series of videos to shed light on supplementation. My question is: How much do kids need? My kiddo eats fortified foods, but probably only once a day, so I suspect we need to be supplementing weekly. What would an appropriate weekly dose look like for a child? And are there any concerns about overdoses at any age?

    Thanks so much!

  • Dz

    VVeeeerrryyy informative!

  • Pincopallino

    Dear Dr. Greger,
    I read on the net some statements about the negative effects of high doses of vitamin C taken together with B12. Sources are not given, or taken from general encyclopaedias. I found only one reference to a scientific study, from the ’60s in Russian in an obscure Russian journal. Do you know whether this statement is correct? If yes, do you suggest to avoid taking normal doses (below 1g) of vitamin C together with B12 supplements? Do you have any reference on this subject?
    Thank you in advance.

  • LumLum2500

    Unlike Dr. Oz, whose shows seem more like infomercials for supplements that we can’t afford if we bought everything he recommends, Dr. Greger always considers cost when discussing supplements, and I appreciate it.

  • mikeysbro

    There are several forms of b12 (like 8 to date). Thus its important to understand that cyanocobalamin and cobalamin are two different forms of b12. Cyanocobalmin is toxic 1. Nutritional yeasts commonly have this form of b12(such as red star re fortification Conversely, cobalamin found in plants can be either assimilable or not. Chorella, nori, 2 unwashed unsprayed produce 3 has the usable form while spirulina does not. Our understanding of b12 was enhanced by this study from MIT 3 a few years back which helped to solve the mystery of b12.



    Thus the cheapest source may not be the best source as its always the best choice to get our nutrition from the plants.

    • Cyanocobalamin is not only cheapest but best studied to prevent and reverse B12 deficiency safely and effectively. I’m afraid none of the plant sources you list are reliable sources. See here for a review of the available science. Thanks for leaving a comment!

      • mikeysbro

        so you are saying MIT, pubmed , etc are not reliable sources of information?

        • pubmed is just a database of articles, some useful, some less so. And the MIT source you cite does not appear to support your assertions. The paper cited in the news release you mentioned is available full-text here.

          • mikeysbro

            so what do you do with the studies like the one cited that show cyancobalamin is toxic and other studies about cobalamin in chorella, nori are bioavailable?

          • Did you read the review link I sent? One cannot rely on chemiluminescence to determine human bioactivity. I’ve addressed cyanocobalamin elsewhere. The balance of available evidence clearly shows it is the most safe, stable, and effective form of B12. Thank you for your interest in my work.

          • Massimo

            Dr. Greger,
            what do you think of this study, where the authors have found methylcobalamine (active form of B12) in spirulina?

          • Once again, your question is answered by the link I sent before.

          • Fidel Castrati

            You yourself admit that cyano-b12 is not the safest & most effective form of b12 for everyone. Common sense suggests hydroxocobalamin is superior to cyano-b12, since it has the added ability to bind cyanide which all of us can breathe in from second-hand smoke, exhaust fumes, etc. It’s so effective at binding cyanide that it’s used as an antedote in cyanide poisoning. Methylcobalamin & adenosylcobalamin also appear superior to cyanocobalamin, since they are already active and do not need to be detoxed to work for us. There are many who haven’t been able to sustain vegan eating, and maybe lack of active b12 is the reason, since most are getting their b12 as cyano-b12, either as supplements or in fortified food products. Please seriously consider altering your general recommendation on b12. Either way, thanks for all of your work!

          • mikeysbro

            I read both links but it still leaves most of my questions unanswered; namely is cyanocobalamin toxic as reported, how is it made, is mma testing sufficient for determining b12 levels, and if plant sources are deficient in b12 does it not prove that one is supposed to eat meat, and finally, if a herbivore (ie a cow) maintains adequate b12 levels where do they get it from if not from the bacteria on the plants ? Thankyou, in advance for you answers.

          • mikeysbro

            I read associated links provided (re elsewhere) and they fall short of any explanation to my questions.
            The link has not disproved aforementioned studies (re pub med) that cyanocobalamin is not toxic.
            In addition, no repudiation of the MIT study about b12 as a bacteria found on plants is the source of b12 that animals uptake but apparently humans do not for some unknown reason (though humans seem to uptake animal sources of b12 which they obtain from plants sources ..).
            The only explanation is that I cannot rely upon “chemiluminescence” to determine bioactivity . Hence the recommendation for b12 cyanocobalamin supplementation from non plant food sources (b12 is typically made from sewage).
            This only proves to me that vegans are deficient in b12 and cannot obtain it from plant sources unlike animals.
            Although I find this explanation lacking since animals obtain b12 from plant sources while apparently humans do not. Therefore are you able to address the non plant food cyanocobalamin toxicity issue and the failure of humans to uptake b12 on plants like animals can?
            You see I find it strange that animals can uptake b12 from plants though apparently humans cannot. Though there is overwhelming evidence that animal foods cause destruction of the human body’s systems that they clearly shorten human lifespan. Thus I believe that plants are the food that humans are designed to eat.
            Though this b12 issue makes no sense in that humans are unable to uptake b12 from plants. Therefore in light of the multitude of evidence that animal food causes pathological conditions to arise though humans do not uptake b12 from plant foods, this begs the question as to why humans are not getting b12 from plants.

            Personally, I theorise the the answer is three fold.
            One in that pesticides/herbicides are covering those plants preventing the bacteria from adhering to the plant or even kill them (including in the environment) .
            Two, that the artificial fertilisers etc used in modern agribusiness have destroyed/altered the microorganism environment that create the proper conditions for the bacteria to grow and thrive.(this includes water treated with chlorine, fluoride, etc)
            Three that current scientific knowledge is not sufficient to determine which form of b12 is the best form for humans to utilise including knowledge of how the human body functions as regards to b12 utilisation.

            Thus at this time there is not sufficient knowledge to understand the b12 situation properly.

          • elsie blanche

            Have you considered that humans were/are meant to consume lots of bugs and insects, worms, etc. that would be crawling all over their raw greens and fruit if it were not for modern day sanitation practices? And these insects, earthworms, etc. have ample B12 amounts, actually, quite high and noteworthy in crickets and mealworms, two insects that cattle and other grazing creatures in nature devour as the slurp up their greens in the fields. And maybe it isn’t that the animal foods are harming humans, it might be that the cooked animal foods/proteins are what is truly harmful, and that ingesting raw insects is something humans have been doing (and could not avoid!) for the majority of our existence. Raw insects, full of complete protein, blood, intestines, poo, pee, and B12 in large amounts, not small amounts. It is actually quite normal for all supposed non-meat eaters in nature to ingest these insects. It is who they are, and it is who humans are (were before the kitchen sink and supermarkets and recent agriculture practices.

            Your thoughts.

          • mikeysbro

            These animals/ insects are just getting the bacteria from the plants thus humans can get their b12 from plants too. Though because the water is; chlorinated, while plants are sprayed with petro chemicals (oil based ) pesticides etc, and the soil is pumped full of inorganic minerals destroying the micro flora (that create bacteria) bacteria that would normally be present with plants is destroyed. Thus eating animals/insects is like getting protein second hand from the plants where the original protein source comes from.
            Though these sources because they are second hand are concentrated in various toxins thanks to the manipulation of crops and are concentrated sources of protein the human body reacts to by developing disease as a result. Thus the solution is not to eat the animals/insects but to figure out why bacteria is being destroyed on the plants humans eat while animals/insects are getting their nutrition from what they eat. In this way humans might learn not to destroy the environment by attempting to control it but rather to work with the environment in order to achieve a sustainable synergistic harmony with our environment.

      • Ravi K

        I seem to recall that the type recommended for supplementation was methylcobalamin. I am confused now. Is CyanoCobalamin better than MethylCobalamin? What is the difference between the two?Thanks.

  • BanGMOs108

    Dr. Greger. Most of the cyanocobalamin on the market is recovered from activated sewage sludge or chemically produced. How can we tell if it’s from sludge or not. In this light, methylcobalamin seems a safer choice.

    Also I would hope that you would warn people off of vegetable sourced B-12.
    It’s an analog which blocks the uptake of true B-12, the result being that the body’s need for B-12 actually increases!

    • Tom Goff

      As I understand it, the claim that most cyanocobalamin is extracted from activated sewage sludge is just an internet myth.
      If you have any credible evidence to the contrary, I’d be interested to see it. By credible I don’t mean some quack, charlatan or crackpot with a website but a professional journal etc.

      If you are a full vegetarian, you don’t eat dairy because it comes with too much baggage – transfats, saturated fats, cholesterol, hormones and antibiotics. It’s far safer to just take a B12 supplement.

  • Israel Navas Duran

    Actually your poo would be much more expensive than your pee.

  • Sílvia Melo

    Does this applies while taking a chlorella our spirulina supplement?

  • Don Perlis

    There are many conflicting reports as to the safety of high doses of B12. Some (like you) say it is perfectly safe. Others (like the Mayo Clinic) say it must be used with care in people who have dermatologic, urinary, gastrointestinal, hematological, and other issues. How can one tell who is right?

    • guest

      B12 supplements totally screwed with my body. Totally threw off homeostasis. Never been the same. Amnesia from
      methylcobalimin, heart stoppage from cyanocobalamin. Other issues as well. I am not the only one. How long have
      humans been popping a pill with no long-term health record, and a pill that contains an amount of B12 that the immune
      system has never had to register, up until this century?

      Read the research/comments (google) regarding horrible reactions to B12 supplements.

  • Eva

    Looking forward to seeing you next month in Marshal Texas

  • Gregg Stern

    What are your thoughts for those of us vegans near & over 50? More than 2,500 mcg of B12 per week? Use the Hydroxo or Methyl forms? Are you a fan of either the Hydroxo or Methyl forms over the standard Cyano form? I would appreciate your thoughts. Thanks

  • Soymoon

    I am over 50 and have a B12 absorption issue. I felt as if I had lightning bolts up and down my legs. My doctor recommended 5000mcg B12 every day. Is this over kill? It stopped the pains. Now I have a bunion that can become quite painful. Taking 10,000mcg every other day settles it down.

    Is this crazy or am I actually helping the nerve pains go away? Thanks!

  • Margasandoval65

    Dr. Greger, you must know that I love the way you teach us. If you had been one of my professors in the university, be sure, that I would never have miss one of your classes, no matter if I were in labor. Margarita Sandoval.

  • Derrek

    Where can I get b12 for $40 for 20 years. Any links?

  • Victoria

    Dear Dr. Greger,
    I’ve been vegan for the last 1.5 years and reciently got tested for B12 levels in blood. Turns out they came up pretty low, 250 pg/ml.
    I was wondering how much cianocobalamin should I take to boost B12 levels, and for how long.
    The cianocobalamin I could get comes in tablets (5 mg of cianocobalamin + vit. B6 and B1).
    Always following your amazing work.
    Thank you.

  • Dr Health Flex

    Doc ,interesting video, however cyanocobalamin has two cyanide molecules that once bound to IF are routed to the liver for methylation-conversion to methylcobalamin the bioavailable form. Synthetic B-12 is actually harmful as it is synthetic B-9 folic acid. Those who suffer with MTHFR can’t process these synthetic vitamins and those who can are robbing from the methyl groups when they have a heavy load already due to our ever increasing toxic environment. Cyanocobalamin is actually banned in some foreign countries such as the UK. I love your videos on estrogen from animals so keep
    up the good work.

    • elsie blanche

      Is the methylcobalamin form of B12 something you consider as synthetic, and does this methyl-form of B12 also rob from the methyl groups, as you claim the cyanocobalamin form does? Thanks for feedback on this.

      • William Hiatt

        As a matter of Fact the UK has banned Cyanocobalamin. Here is a link to a white paper and additional research.

        • elsie blanche

          What form of B12 are you currently taking? Ever try the hydroxocobalamin?

  • Dr Health Flex

    As a Formulator of Transdermal nano patches I use only metylcoblamin B-12 with all my patients to bypass the hepatic pathway.

  • Natalia Nikolaevna Govyadnikov

    How to view transcripts?

  • Alexandre B

    Hi, I have read pratically all the post, but I have not find good URL for cheap B12, I mean large supply for 1 years and up. Presently I use Jamieson B12 2,500 mcg sublingual and cost me about 20$ for only 60 capsules.

    Anyone can help me to find where to buy in bulk online ?

    Thank you !

  • sara

    which web site or company should i trust for toxic free vitamin

  • Derrek

    Where can you find the $40 for 20 years? Any cheap sources you recommend?

  • veronika neukirch

    i noticed in that diagram above, the gallbladder also has a part to play in the absorption process. does one have to up the b12 dosage or frequency of taking b12 tablets, if the gallbladder has been removed?

    • veronika neukirch

      in fact what are the best ways to up absorption of b12?

    • This should not be a problem. The only time the dosage needs to be adjusted up is when you have problems making intrinsic factor. Pernicious Anemia is an autoimmune condition which causes the loss of gastric cells which make intrinsic factor which gives us the 1.5 part of the equation in the video. Given individual variation it is always easy enough to get your B-12 level checked with other blood work.

  • Would you be able to get vitamin B12 from lacto-fermented vegetables?

    • Joseph Gonzales R.D.

      Hi Sarah. No :( I just posted a bunch of links to Jeff’s comments above if you are looking for more information.

  • Laloofah

    I’m about to re-stock my Vitamin B-12 stash, and wanted to find out more about the cyanocobalamin vs methylcobalamin issue first. Since every one of Dr. Greger’s informative B-12 videos and articles seem to contain at least one question about the difference, efficacy, safety, etc, between the two types, I thought I’d share this except from an article on B-12 by Dustin Rudolph (the “Plant-Based Pharmacist”) that I found very helpful (the original article cites sources & includes links to additional info, which are not included here):

    “Cyanocobalamin is a synthetic version of vitamin B12. After ingestion, cyanocobalamin is broken down into the two active forms of B12 known as methylcobalamin and 5-deoxyadenosylcobalamin. The active form methylcobalamin is an essential co-factor in the production of healthy red blood cells. The other active form, adenosylcobalamin, is an essential co-factor in the maintenance of healthy nerve cells and healthy red blood cells. Because cyanocobalamin is broken down into both active forms of B12, it is the preferred supplement for use in healthy individuals.

    There have been concerns brought up by some individuals that during the metabolic breakdown of cyanocobalamin, cyanide is released as a byproduct. Cyanide can be toxic to the human body in large amounts. However, the amount of cyanide contained in a B12 supplement is not physiologically toxic to the human body. The only possible theoretical exception might be in patients who have kidney disease. Keyword emphasis on the word might. These patients have an impaired ability to clear cyanide, which could lead to elevated cyanide levels over time. A better option for those with kidney disease may be methylcobalamin due to this.”

    • Joseph Gonzales R.D.

      I think you got it right. If kidney failure is an issue shoot for methylcobalamin. Thanks for the article!

      • William Hiatt

        our methyls groups are already being taxed to failure due toxins in food, environmental toxins, depleted glutathione levels, why pile on more work for the methylation groups, and this is not even addressing those with SNPs- Methylcobalamin is as cheap and in the form of transdermal applications higher in efficacy without the risk of dosage dumping.The other area Jack does not address is the Lock and Key fitting of synthetic vitamins.Methyl is the bioavailble form. By supplementing with transdermal nano patches you do not have to be concerned with problems in binding with IF (Intrinsic Factor) Many medications as well as PPI interfere with this so even if you are eating foods high in B-12 you still may suffer from malabsorption.

    • factsoverFearRZ

      I think your concerns for cyanide may have been overblown, the RD Jack Norris does the math, you are likelier to get several times more cyanide in flax crackers than a little b12 see link

      • William Hiatt

        RD Jack Norris in fact makes a salient point that our methyls groups are already being taxed to failure due toxins in food, environmental toxins, depleted glutathione levels, why pile on more work for the methylation groups, and this is not even addressing those with SNPs- Methylcobalamin is as cheap and in the form of transdermal applications higher in efficacy without the risk of dosage dumping.The other area Jack does not address is the Lock and Key fitting of synthetic vitamins.Methyl is the bioavailble form. By supplementing with transdermal nano patches you do not have to be concerned with problems in binding with IF (Intrinsic Factor) Many medications as well as PPI interfere with this so even if you are eating foods high in B-12 you still may suffer from malabsorption.

    • William Hiatt

      This is perhaps an over simplification, the body is already under assault from environmental toxis and the vast majority of people are low on glutathione so to rob unnecessarily from the methyl groups by ingesting cyanocobalamin is at lt best counter production and at worst ( for those with polymorphism MTHFR) unhealthy.

  • Ivail Sve

    What about Dr Virginia Vetrano study(book), here is in short:

  • Jeff and Karen Hay

    Aloha Dr. Greger and Nutrition Facts Folks,
    We just heard Wednesday’s video (July 15) on B-12 and read all the comments beneath and we came away wondering about a few things. The B-12 that we take we buy from Dr. Goldhamer at TrueNorth. It is 1,000 mcg capsules of methylcobalamin – we wonder where does the methylcobalamin come from? Our understanding is that it is a bacteria – is this correct? What is the bacteria source? Also interesting to us was the discussion regarding blood levels of B-12 and whether that B-12 is actually being assimilated. Is there some reliable method for finding out whether your B-12 is adequate and whether it is being assimilated? And finally, are there food sources of B-12? Since the absence of B-12 seems at least in part to be caused by the fact that our plant food supply is overly sanitary wouldn’t organically grown mushrooms that aren’t “cleaned” be a source of B-12? We have other questions but this is a good start.
    Jeff and Karen HaySanta Cruz, CA

    • Joseph Gonzales R.D.

      Aloha Jeff and Karen! Thanks for reposting. B12 is super important. Adults needs roughly 2.4 micrograms per day. In supplement form it comes in higher doses. Any brand is fine and you can find cheap sources. Dr. Greger talks about exactly what B12 is in this video. You are right it’s a soil bacteria. Many people believe we obtain some from dirt but there is no strong proof of this, if any. From dietitian Jack Norris’s post: “Vitamin B12 is a complicated vitamin with a unique absorption mechanism and a number of inactive analogues (molecules that appear to be active B12, but actually are not) that possibly interfere with its function. Vitamin B12 is generally found in all animal foods (except honey). Contrary to the many rumors, there are no reliable, unfortified plant sources of vitamin B12, including tempeh, seaweeds, and organic produce.”

      We have tons of videos on B12, including the safest source where it mentions how we actually do produce B12 it’s just too far downstream to be absorbed.

      Check out more on Dr. Greger’s Optimal Nutrition Recommendations. And let me know when you have more questions so many folks here have solid answers and suggestions.


    • Joseph Gonzales R.D.

      From NIH “Only about 10 mcg of a 500 mcg oral supplement is actually absorbed in healthy people.” Reference

  • William Hiatt

    Elsie, Methylcoblamin is the most bioavailable form and does not rob from the Methyl groups

    • elsie blanche

      How do you know it does not rob from the methyl groups? I appreciate your statement and the
      time you have taken to provide this, but I see no data or science that proves it either does or
      does not. Is this simply a theory of yours, and others? Thanks.

      • William Hiatt

        Did you read the white paper, I also have clinical results and of course a good Doctorate’s knowledge of physiology tells us how the nutrients are routed to the liver to make them Bioavailable. Link to published article

        • elsie blanche

          Just read it. Wondering what your thoughts are on hydroxocobalamin. I know people who have had real bad reactions to methylcobalamin, some who claim it might have irreversibly made their body worse. Who knows that high dose vitamin supplements can trigger, alter, change, in some people. We are not all the same, and our immune systems and homeostasis, in my opinion, can be altered/sensitive to these high dose and different forms of vitamins, methlcobalamin included. I did get better sleep with the methyl B12, but then it went in the other direction and things got way worse. Cyano form caused my heart to stop beating.

          Hydroxocobalmin is somewhat tolerable, at best, but none of these supplements have lowered my homocysteine and methylmalonic acid levels. Only shellfish have done that. Frustrating. You have any experience with the hydroxocobalamin B12?

          • William Hiatt

            Elsie , what dosage were you taking and how often? B-12 will remain in the liver for a period of time, My patients wear a transdermal patch one day a week. Those who have been tested with high Homocysteine levels have had reductions as well. Are you sure you do not have MTHFR? It might not be a bad idea for you to use Nano patches Because the patches bypass the hepatic pathway the efficacy is higher with safer smaller doses. These patches are used in clinics all over the world by Integrative and functional med docs. They resolve the dosage dumping issue by using a time release function. My email is

          • elsie blanche

            Have tried all different doses, methods of administration, products/companies of methylcobalamin. I was open to trying out the supplement you suggested but I see it has a lot of other “not-natural” vitamins added to it. Thanks for your efforts.

          • William Hiatt

            Transdermal nano Patches have a higher efficacy with a smaller dose by virtue of bypassing the hepatic pathway and the time release function means you do not over saturate cell receptors giving you small doses through out the day, All our test have shown lower Homocysteine levels and methylmalonic acid.

  • William Hiatt

    Elise I produce transdermal patches with both forms- Methyl and Hydrox- Clinical evaluations have shown a much greater efficacy with Methyl

  • William Hiatt
  • William Hiatt

    Elsie I do produce a Hdroxo B-12 patch as well.

  • Dear Mister Greger and Team,
    an issue spinning around in my head for
    months now. It’s about vitamin B12. As an vegan I supply vitamin B12 of
    course but and this is the question, I never heard that people from
    India, Pakistan or Africa are supplying vitamin B12.
    Is there any study available?
    Or how do this people make sure that the not suffer from to less of it?

    I know that a bacteria living in a healthy earth is producing the vitamin B12, so when we eat some vegetable without washing we get enough vitamin B12. Unfortunately most of the earth ground is not healthy nowadays, because the farmers attitude to use them – no biological farming and more…
    also, where get the people there vitamin B12?
    And second question, could it be that the issue with vitamin B12 is the same as for example Vitamin C, that we have to have a lots of moire daily take in because the Vitamin is not natural? I read some studies that the body by himself decide how much vitamin he assimilate from the nutrition offer (for example from a apple the vitamin C) and it takes a lot of mote intake, when we use chemical vitamins???
    I hope you understand my “kauderwelsch Englisch”….

    • NFmoderatorRenae

      I recently read this study from India which suggests it’s more that you just haven’t heard it, rather than it not existing :)

    • NFmoderatorRenae

      Those countries also have less health care access and likely test less, so less deficiencies are uncovered…

  • Hi, where can I find the cyanocobalamin for the price that you mention?

    I will really appreciate the information

  • Christina Karlhoff

    Hi Doctor Greger :) I have a question that might seem pretty darn obvious: Why can we not re-create or somehow emulate the conditions we had in the past when B12 was in our diet….? I mean, we have probiotics for when intestinal flora need a reboot…why cant we do the same for B12? Doesn’t B12 reside long-term in the liver? Thank you for your time!
    (I try to take a B12 at least once per month, and I have 1-2 Tbsp of nutritional yeast almost every day on my salad.)

  • danieltb


  • A.Ivanov

    Can someone please tell me were to buy a product that meets this recommendation?

    Cyonocobalamin, 2500 Mikrogramm, sublingual tablets.


  • john

    Hello, im currently supplementing with this product,, but not sure what the correct dose should be going by whats on the label and Michaels recommendation, any help most appreciated.

  • danieltb

    Dr. Greger,
    I started taking the B12 from and began having acne breakouts. Will you please consider doing a video comparing the different cobalamins and B12 supplements?

  • Nancy

    “Maybe some Woolly Mammoth pooped upstream”…. lol

  • john

    my bad,I may have mistaken this video with another, but in this video Dr Greger very clearly lays out correct dosage where as i guess some labeling is intended for those whos meat /dairy diet permits a much higher intake of B12 and therefore require a much lower level of supplementation .

  • Patrick Ritchie

    Hi, I am Patrick Ritchie, from Montreal (Canada). What brand would you recommend? I found two available here: Land Art and SISU. Someone told me that Land Art has conservatives in it. I am open to suggestions :) Do you recommend a specific brand (available in Canada)? Thanks in advance!

  • promosinc

    In his book, How Not to Die, Dr. Greger’s recommendation for Vitamin B12 as cyanocobalamin is 250 mcg daily or 2500 mcg weekly for people under 65 years of age. For people over age 65, the recommendation is 1,000 mcg daily. Is there a weekly dosage for people over age 65, e.g., maybe 5,000 mcg — or should people over age 65 always take the daily dosage?

  • Marjorie82

    Hello Dr. Greger! I am in research mode since having an ah ha! moment and thought maybe you and your team could help me. I previously went vegan for 2 years and stopped after having severe acne breakout all over my face, neck, and chest. I had food intolerance testing done and found I was “allergic” to most things vegan (quinoa, almonds, legumes, soy, etc) and thought I couldn’t be vegan anymore. I went on a Paleo/Candida diet for 3 years – my skin wasn’t perfect, but my neck and chest acne was mostly non existent. Last year I just couldn’t take it anymore and went vegan again – regardless of the state of my skin, I just couldn’t eat animal products anymore. I eat a high carb low fat vegan diet as this allows me to stay away from my “allergens” and be vegan. Problem is I go through times of bad acne again – face, neck, chest. I have been bad for supplementing B12 here and there – would order transdermal patches then forget to order more, recently I have purchased injectable B12 and have been giving myself 1000 mcg IM, every week. I have just realized that my bad acne corresponds to when I take B12! I googled it (I know! thats why I need you) and found articles that show that acne bacteria metabolize it and create porphyrins that create inflammation, and can cause acne. So I have a dilemma of wanting to be healthy internally and take B12 (especially since I have Celiac Disease) versus being acne free and not being depressed and want to be a hermit. So I wonder if there is something I am missing – is their research to show that different types of B12 (cyan, methyl, etc) effect the acne bacteria differently? Or would taking smaller doses on a daily basis be better, etc.?
    Thank you for all that you and your team do! I wish I could find a doctor like you.

  • wholefoodjulian

    Hello — Dr. Greger mentions a 20 year supply of vitamin b-12 dosed weekly at 2500 mcg. At the time of the suggestion, he said it was around $3 a year.
    Can you please recommend a good source for 2500 mcg b12?

    • Rose

      Today I came across this Nature’s Bounty B12 supplement from cyanocobalamin containing 2500 mcg in each tablet, just as Dr. Greger recommends. There are 75 tablets, which will last you a year and a half for less than $9. The formula is vegetarian/vegan. You can get it from iherb regardless of where you live.

  • Cleopatra

    Hey Dr. Greger,
    this b12 topic did not really had my attention for a long a time. I’m vegan for 2 1/2 years now and used to take some tablets but I stopped the package was finished, because I read so many controversial comments. Then when I thought I had a deficiency I wanted to try shots, as I wouldn’t have to take them daily and they will be absorbed to a higher percentage (at least what they told me). I did this and I think it worked, but every time I inject my 1000µg of b12 I get horrible breakouts, many little and bigger deap read spots on my forehead. People told me it’s because I have to much b12 and there is no other way for it to get out of the body then the skin.. But I’m not sure. When I took the tablets I didn’t have this problem. I think I ordered Methycobalamin for the shots.. can you help? Maybe the shot is not a high quality one or I just can’t deal with it?!

  • Elainethevegan

    Dr greger. Thanks for what you -your videos have been an immense help to make my family responsible vegans! I have decided to take b12 supplement and was about to purchase cyancobolamin but then came across an article on natural news website about methylcobolamin being the best b12 and cyancobolamin containing cyanide. Can you clarify which one is best? Thanks. Elaine

  • DavidG123

    Dr. Gregger, in How Not to Die you state “there is insufficient evidence to support the efficacy of other forms, like methylcobalamin” and you recommend cyanocobalamin. I checked the references you provided and none mentioned cyanocobalamin or methylcobalamin (only cobalamin). Dr. Furhman’s daily supplement contains methylcobalamin and I wrote to him about it and their response was “it is the physiological form as opposed to cyanocobalamin.” What I have read about cyano- versus methyl- seems to confirm this. Can you please comment on cyano- versus methyl-. Thank you for all your great work! – David

  • Jason Martin

    Some on various internet forums say it’s not safe to use sublingual methylcobalamin supplements if you have mercury fillings. Is this true or false?

  • Lacyrae

    I read an article that said cynocobalamin is the cheap synthetic form and is actually bound to a cyanide molecule and that methylcobalamin is actually better. I found it disturbing since you said just the opposite in your book, can you help clarify this for me please?

  • Ioana Popa

    I’m having such a hard time understanding the amount needed. If I buy a bottle of b12 pills that says “1200mcg” on the bottle, does that mean that the whole bottle contains 1200mcg of supplements, or each pill? Do I need to take two whole bottles per week? I really don’t get the conversion or what the measurement on the bottle means.. can someone please help me out?

    • Rami Najjar – NF Moderator


      1200 mcg per pill is what is almost always listed, I have never seen a supplement list the entire dosage from consuming the entire bottle. 1 pill every 2-3 days would be sufficient.