Which Type of B-12 is Best

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Which type of vitamin B12 is best–cyanocobalamin, methylcobalamin, or hydroxycobalamin?

I have followed you for years and purchase your tapes. Met you in Ann Arbor at the food co- op. Is it true Cyanocobalamin b12 ( which you recommend for us as vegans) turns into cyanide and the best b12 to take is hydroxycobalamin?Per Raymond Francis MIT scientist. That’s what his website shows anyway. His comments were it is man made , not natural, and not well utilized. What is absorbed is turn into cyanide. Could you please clarify, help.

David Tunison / Originally asked on Vegan epidemic


Let me guess: Mr. Francis sells hydroxycobalamin supplements?

It’s like the whole coral calcium scam. Calcium is cheap as chalk–in fact it is chalk! So how are you going to bilk people out of lots of money? You sell some sort of special calcium. Same with B12 supplements.

B12 is so cheap to produce that supplement manufacturers try to come up with all sorts of fancy ways to “add value” to products so they can charge $30 a bottle. Unless you’re a smoker, have kidney failure, or base your diet around cassava root, cyanocobalamin should be fine. That’s what I take!

Image credit: epSos.de / Flickr


Michael Greger M.D., FACLM

Michael Greger, M.D. FACLM, is a physician, New York Times bestselling author, and internationally recognized professional speaker on a number of important public health issues. Dr. Greger has lectured at the Conference on World Affairs, the National Institutes of Health, and the International Bird Flu Summit, testified before Congress, appeared on The Dr. Oz Show and The Colbert Report, and was invited as an expert witness in defense of Oprah Winfrey at the infamous "meat defamation" trial.

165 responses to “Which type of vitamin B12 is best–cyanocobalamin, methylcobalamin, or hydroxycobalamin?

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  1. But, is cyanocobalamin from animal sources? In another video, you mention B12 supplements for ~$2/year, was that a vegan B12 supplement? Methylcobalamin claims to be vegan, are there cheap sources for it? Not asking you to recommend a retailer specifically but I just wanted clarification… Thanks so much for the wonderful source of FACTUAL information! Keep up the great work! :)

        1. The Wikipedia entry for B12 talks about how certain conditions can affect B12 absorption in the body. People have have conditions where their digestive tract cannot absorb B12, but as far as I can tell you can always absorb it through the very small veins and capillaries under your tongue, or for some people an intravenous injection. Swallowing if OK if your body can absorb B12, and some people do not like holding a pill under their tongue for 10 minutes or so.


    1. Some 40 years ago, I used to consume Kal brand nutritional yeast for vitamin B-12. But, I wasn’t vegan at the time. I consumed it because it helped me quit smoking — cold turkey; I also fed it to my dog when I was making my her pet food. She did better on homemade pet food with nutrients added than I commercial pet food and that was before they were genetically engineering pet foods! The veterinarian, Richard H. Pitcairn recommended Kal brand, which I bought at a local health food store.

      I now take Bluebonnet Earth Sweet Chewable Vitamin B-6, B-12 plus Folic Acid. I was looking for a vitamin B-12 that was 1000 mcg. So many have 5,000 or more, which I did not want. I’ve also read in the Nutrition Almanac that vitamins should not be taken alone because they can deplete other vitamins in the body. And, in addition, one of the physicians who subscribe to this list, suggested this Earth Sweet Chewable Vitamin B12 for me, when I went vegan.

      Thus far, I’ve had no problem and it certainly makes me feel better.

      1. The B12 version I take has 1000 mcg. It also has 800 mcg of folate, which is easily assimilable, and the only kind I can take for my genetic compromise (40% of Americans are genetically compromised with MTHFR).

    2. Hi Joe, I have the exact same question as you. Did you find out what is the best brand to buy? Thanks for sharing, Hector from colombia

    3. Dr. Greger,

      What about the methyl version of B12 for those who have a MTHFR compromise (I am heterozygous)? Regular B vitamins do not get assimilated by MTHFR compromised folks. I noticed a problem with B complex vitamins when I was in my teens in the 1970’s, yet the MTHFR gene was not discovered till mid-1990’s; now I know why I could not take them. I do well on the methyl version of B12.

      1. Hey Cynthia, thanks for writing. I’m not exactly clear on what you’re saying here. If ‘assimilation’ is the same as ‘absorption,’ any kind of B12 should do – the MTHFR gene does not affect gut absorption of B12 (which if I remember correctly, is absorbed in the ileum). I’m also unclear about what you mean when you say you noticed a problem with B-complex vitamins when you were in your teens. Have you had your serum B12 checked, or an MMA test done? Methylcobalamin is a good choice for people with peripheral neuropathies, but apart from studies in dialysis patients I don’t see evidence that it reduces homocysteine levels more effectively than other forms of B12.

    4. Hi, Joe- I’m a little confused here, too. I got a huge supply of methylcobalamin for next to nothing. I’ve been taking 5000 mcg per week (once a week). I hope I’m getting my needs met there. I also eat some foods with added b12 like soymilk and nooch. I have a bunch of 5000 mcg methylcobalamin left, so hopefully it works!

        1. it’s not that they’ll have problems absorbing the B12, its the fact that Cassava root naturally contains cyanide in it which would potentially exacerbate the concerns about cyanocobalamin cyanide problem – the cyanide levels from cyanocobalamin on its own will not be harmful. But in combination with cassava, it could become a problem. Cassava is cooked and processed in a way to remove most of the cyanide and make it suitable for daily consumption, but traces potentially remain and you probably don’t want to chance things. Note that this is only a concern for people whose DAILY STAPLE FOOD is Cassava.

  2. Dr. Greger, you aren’t concerned that people who don’t eat as super-healthy as you might not have the ability to unload the cyanide in cyanocobalamin in order to utilize cobalamin? My concern is that for many, cyanocobalamin is too stable a molecule in which the cyanide is not that easily released. Can you dig up some science on the mechanism by which the body detoxes cyanocobalamin and how involved that process is?

    The video at http://bit.ly/toxic-b12 says that cyanocobalamin can actually LOWER
    true b12 levels. Yes, the guy is selling a drink mix with hydroxycobalamin, but i still sense there is some degree of truth in what he’s saying. That is, for some, and more than you might expect, cyanocobalamin might actually be unsatisfactory of even harmful. After all, it is not the way humans have been getting b12 up until very recently in terms of the overall human timeline.

    1. “Yes, the guy is selling a drink mix with hydroxycobalamin”

      That’s really all that needs to be said. I don’t listen to anybody who spouts unproven theories about vitamins, especially if they’re trying to push their lame product on me.

    2. There is no evidence suggesting it lowers b12 levels, total scam is my theory. That said the levels of cyanide in this vitamin are so small that as he said, unless your already smoking it would do nothing at all. you would have to eat a smll bottle full to get a single cigarettes worth, and that is not recommended anyways. your body needs an increadibly small amount of b12 size wise, so though it has this toxin it wont effect you.

      1. Aren’t we all smoking to some extent? That is, there are poisons in our air from car exhaust, etc. I don’t want a known poison attached to my vitamin on top of that. I have a feeling one of Dr. Greger’s future videos will refer to a study showing why the bio-active forms of B12 are better for us than cyanide-B12.

  3. Dr Greger. Thank you for all of your info / sharing. Regarding B12 recommendations, you say that the Cyanocobalamin should be fine. I wanted to double to see if you feel this is true for Vegans..because 2 Vegan sources I have communicated with recommend the methylcobalamin form of B12 b/c it is the natural form. Could you please share your thoughts, advice. (Would there be a negative to taking the Methylcobalamin form over the Cyanocobalamin form)? Thankyou!

    1. We don’t have as much data (in terms of proper dosing and efficacy) on preventing/reversing B12 deficiency in vegans with any other form that cyanocobalamin. Until there is I’m less comfortable recommending it.

      1. What about the B12 in coconut milk. One cup = 50% of daily requirement. Other plant based milks also have it. I have asked this question on three different sites and have yet to receive a comment. This seems an easy way to ingest enough B12, unless the body can’t utilize it in this form. Please comment.

        1. Mary: There is nothing wrong with the B12 in plant based milks. Brenda Davis and and Vesanto Melina are RDs who are well respected and have been featured here on NuritionFacts. In their great reference book, Becoming Vegan, they state: “The B12 present in supplements and fortified foods can be relied on and is well absorbed.” from page 127
          Now having said that, I don’t think I would personally incorporate a lot coconut milk into my daily diet. Coconut is especially high in saturated fat compared to other plants. So, you are better off on a daily basis with say almond milk if you can eat almonds or any of the other types. That’s just my 2 cents.
          Does that answer your question?

      2. What are your thoughts regarding this study? Freeman AG. Hydroxocobalamin versus cyanocobalamin. J R Soc Med. 1996 Nov;89(11):659.

      3. Dear Dr. Greger,

        Given the necessity of the B12-supplement for vegan diets, it’d be great with a follow-up on this question.

        Cursory research indicates that “Methylcobalamin that is ingested is not used directly as a cofactor, but is first converted by MMACHC into cob(II)alamin. Cob(II)alamin is then later converted into the other 2 forms, adenosylcobalamin and methylcobalamin for use as cofactors. That is, methylcobalamin is first dealkylated and then regenerated.” (wikipedia.com)

        ‘Genetics Home Reference’ confirms with “Research indicates that the MMACHC protein plays a role in processing different forms of vitamin B12 so that they can be converted to either of the cofactors, AdoCbl or MeCbl.”, with both cofactors being necessary for different metabolic processes.

        A review study on the efficiency of different forms can be found here

        and summarizes the issue: “At doses commonly used in treatment or prevention of Cbl
        deficiency, all Cbl forms appear to be absorbed, internalized by the cells and follow the intracellular metabolic pathway that converts all forms into the common intermediate [Co2+]Cbl
        that in its turn transfers into the functional coenzymes, MeCbl, and AdoCbl. MMACHC exhibits a broad specificity for different Cbl forms and removes the upper ligand of incoming cobalamins, thus MeCbl and AdoCbl coenzymes can be synthesized from all available Cbl forms. Available clinical studies are non-controlled trials and almost all of them show the beneficial biological effects independent of the form that has been used.”

        However, as a layman, I am unable to verify the quality of the studies in question, and would very much appreciate your evaluation of them.

        Here’s to hoping you have time to revisit different forms of B12, so we can get something like a definite answer to this question. For now, I’ll go with 500mcg methylcobalamine (as it’s what’s available at my location).

          1. It’s not, though I thank you for the reference. Dr. Greger doesn’t address the various (4) sources of B12 in that post, or in any of the videos to which it refers.

            But the review study answers it in detail, and other studies on PubMed measuring blood levels of B12 following ingestion of oral supplements (vs. lingual) confirms oral supplementation as sufficient as well.

            A daily oral 500mcg methylcobalamine supplement should therefore – according to this research – be sufficient to prevent B12-deficiency.

            But it would have been nice to have Dr. Gregers word for it.

  4. I just read this small paragraph on cyanocobalamin and it does not clarify if cyancobalmin is toxic as reported. Furthermore, it is still unclear how the cyanocobalmin found in nutritional yeast is made.

    1. Cyanocobalamin is made almost exclusively outside the animal and plant kingdoms. I would imagine that the cyanocobalamin made in yeast is actually made by yeast.

      1. There are many types of b12 though nothing I have read that says that b12 is produced by yeast though red star yeast has added b12 which changes the color to yellow which is my current understanding. In addition, it is unclear where that added b12 is coming from since red star does not reveal the source. Here is an excerpt from wiki ”

        Cyanocobalamin is commercially prepared by bacterial fermentation. Fermentation by a variety of microorganisms yields a mixture of methyl-, hydroxo-, and adenosylcobalamin. These compounds are converted to cyanocobalamin by addition of potassium cyanide in the presence of sodium nitrite and heat. Since a number of species of Propionibacterium produce no exotoxins or endotoxins and have been granted GRAS status (generally regarded as safe) by the Food and Drug Administration of the United States, they are currently the preferred bacterial fermentation organisms for vitamin B12 production.[5]

        Historically, a form of vitamin B12 called hydroxocobalamin is often produced by bacteria, and was then changed to cyanocobalamin in the process of being purified in activated charcoal columns after being separated from the bacterial cultures. This change was not immediately realized when vitamin B12 was first being extracted for characterization. Cyanide is naturally present in activated charcoal, and hydroxocobalamin, which has great affinity for cyanide, picks it up, and is changed to cyanocobalamin. Cyanocobalamin is the form in most pharmaceutical preparations because adding cyanide stabilizes the molecule.[1]”

        Thus cyanocobalamin is a fermented product using propionbacterium ”

        Propionibacterium is a Gram-positive, rod-shaped genus of bacteria named for their unique metabolism: They are able to synthesize propionic acid by using unusual transcarboxylase enzymes.[3] …

        Members of the genus Propionibacterium are widely used in the production of vitamin B12, tetrapyrrole compounds, and propionic acid, as well as in the probiotics and cheese industries.[6]

        France accounts for 80% of world production, and more than 10 tonnes/year of this compound is sold; 55% of sales is destined for animal feed, while the remaining 45% is for human consumption.[6]” wiki

        One could assume that the cyanocobalamin is fermented with the yeast but that is only an assumption.
        The following is a direct quote from Lesaffre the manufacture of red star nutritional yeast

        “What is Nutritional Yeast?

        RED STAR Nutritional Yeast is a primary grown pure culture strain of Saccharomyces cerevisiae. It is a powdered yeast without leavening power, marketed for its protein and vitamin content. This type of yeast is available in both powder and pill form.

        Nutritional Yeast is an excellent source of protein, rich in many of the essential amino acids that complement proteins available from other sources such as corn, wheat, and soy. RED STAR Nutritional Yeast contains an average of 50% protein by weight.

        RED STAR Nutritional Yeast is also a rich source of B-complex vitamins that are important for normal and healthy body functions.

        How nutritional yeast is made

        RED STAR Nutritional Yeast is primary from pure strains of Saccharomyces cerevisiae grown on mixtures of cane and beet molasses. After the fermentation process is completed,”Cream yeast” is heated by means of a heat exchanger and held at pasteurization temperatures for a period long enough to inactivate the yeast. During this holding period, all necessary vitamins are added to meet the requirements of the specific type of nutritional yeast produced.

        The yeast is then drum dried before it is ground and shipped to consumers. The drying process assures that all the cells are inactivated in order for the full nutritional benefits to be available.

        Photo Key:
        A) “Seed yeast” is grown in small flasks
        B) “Seed yeast” is transferred to 1,000 gallon tanks for fermentation (becomes “stock yeast”).
        C) Alcohol from fermentation separated from “stock yeast”
        D) “Stock yeast” moved to refrigerated tanks (“Trade Fermenter”) for fermentation cultivation
        E) Sterilized molasses, air and nutrients are added to “stock yeast”
        F) When yeast is ready to be harvested, fermented yeast liquid is passed through a “Separator” to produce “cream yeast”

        G) “Cream yeast” is heated and pasteurized, ***********necessary vitamins are added*********** stars are my emphasis.

        H) Vitamin-enhanced “cream yeast” is cooled
        I) “Cream yeast” is drum dried
        J) The dried yeast is put through a grinder to produce a fine powder
        K) Nutritional yeast is packaged and ready for shipping

        Visit our Nutritional Yeast site at www lesaffre ”
        Hence my question, where is the cyanocobalimin coming from and is it added or grown on the yeast ? Though no one has been able to answer. I guess I will have to call the company…

          1. Well I specifically looked it up sometime ago including cyanocobalamin to research nutritional yeast . Which is why I question the safety of using it compared to other types of b12 such as hydroxocobalamin though it seems that very little information exists on the subject of different b12 types.

        1. Dr Greger, I assume this is true in that B12 cyanocobalamin is NOT made by cyanobacteria but instead by propionbacterium, as mentioned above. I was concerned given the issue of BMAA being produced by cyanobacteria correlating with ALS (volume 23 dvd).

    1. That article says to take “Cobalimin” and not Methylcobalamin, but Cobalimin is a general term for all forms of Vitamin B12 according to wikipedia. Is it referring to Hydroxocobalimin?

    1. I’ve found it to be better. I’ve felt nothing of of cyanocobalamin, even at high doses taken over a long duration. Methylcobalamin, which is NOT expensive ($4.99 for 60 tabs (2,500 mcg
      dose per capsule over at Swanson) is a much more bio-available choice.

  5. I can’t even believe this is up for debate. Most physicians will tell you that B-12 is poorly absorbed because it’s destroyed by gastric juices. I’ve known several physicians who recommend B-12 injections as the most effective way to make use of B-12. In most cases, I’ve found them to be right. I was sluggish and tired, and my intake of cyanobobalamin was more than the average bear. I felt nothing. About two weeks into a methylcobalamin-containing supplement, I noticed a huge difference that has been sustained. Dr. Greger’s dismissive nature on this matter puts me off.

    1. Once you understand the biochemistry involved avoiding Vitamin B12 deficiency and treating Pernicious Anemia(PA) via the oral route becomes straightforward. In my clinical experience I have never had to resort to injections if you use high dose oral medications in the case of PA an autoimmune disorder where the body stops producing intrinsic factor which helps is necessary for the active phase of B12 absorption. See Dr. Greger’s 5 video’s on B12 beginning on February 3 2012. Using injections can be useful in the initial treatment of B12 deficiency. It is important to work with your physicians but there is ample literature to support oral therapy. In addition to PA there are certain inborn errors of metabolism that would require injection. Methylcobalamin may offer a theoretical advantage over cyanocobalamin but it is more expensive… if you go to the website referenced by Toxins it is 14 times more expensive. Cyanide is present in foods so our bodies are equipped to eliminate it. The total amount consumed is important. I am not a physician who believes that “Vit B12” is destroyed by gastric acid. As a clinical matter the use of acid blocking agents and antacids can contribute to Vitamin B12 deficiency. All this said there are individual differences and if methylcobalamin works better for you then cyanocobolamin I would certainly go that route. You need to work with your physician(s) to work out what works for you.

      1. I hold the personal believe that cyanocobalamin is cheap for a reason. It’s synthetic garbage. Even you conceded that its bioavailability can be trivial. Who cares about cost when it’s your health and well-being on the line? It’s like all the people who gripe about the cost of eating healthy. It’s still cheaper than chemotherapy.

        Right now I’m paying $15.99 to have 60 days worth of a B complex that contains methylcobalamin and also contains medium-chain triglycerides. I can’t imagine that $8 a month is beyond the reach of most health conscious people

      2. And I just checked Swanson Vitamins and found you can by their brand of methylcobalamin for $4.99 for 60 tabs (2,500 mcg
        dose per capsule). You consider that expensive? You consider that TWELVE times more expensive than the cheap and inferior cyanocobalamin?

      3. Hi Dr. don,

        Something that hasn’t been mentioned is what is in the supplements. I had a hard time finding a B12 that didn’t have sorbitol. I went through a bout of IBS with stomach cramps and diarrhea. Once I eliminated the sorbitol it cleared up. The B12 I finally found was methylcobalamin drops. (thank you Brian) Have you found patients with this issue with the sorbitol?

        1. I am personally appalled with the amount of products that now contain sorbitol. It is almost deadly for me, and extremely painful for one of my children who suffered from IBS all his life. It is REALLY INSIDIOUS that it is allowed in INFANT AND CHILDREN products from toothpaste to medicines, not to mention many, many foods. Whoever within the FDA has allowed this is truly wretchedly evil; the only other excuse would be complete ignorance, and I daresay that is a possibility, but would bet MONEY on the fact that it is totally a “money-oriented” decision on the part of those who have promoted this BAD DECISION!! When I think of the many infants and children that must be suffering the pains of sorbitol sensitivity, it makes me sick. Having given birth, naturally, to 5 children, I KNOW pain, and sorbitol sensitivity can be equally painful!!

          1. similar to the use of carrageenan in many products. It is a KNOWN inflammatory agent and has been banned for children’s formulas in Europe. But it is a cheap thickening agent so it is in many things like ice creams and yogurts. Even in toothpastes and cosmetics! I learned about it’s harmful nature when reading about the ills of commercial pet food. At the time it was a common ingredient added to thicken canned pet food. Thankfully it is finally becoming less used, thanks to MANY consumer complaints. My allergist warned me to avoid it completely, but many medical professionals don’t even know what it is. Researchers often use carrageenan to purposely induce inflammatory for studies. That shows you how powerful it’s bad effects can be.

    2. I have found the same with myself, suffering from a long term fatigue (that is probably a very different ailment than just B12 deficiency). Methylcobalamin from ProHealth is my favorite, at 5mg dose. It has a little sorbitol. I just switched to another brand and it has too much Manitol and dissolves too quickly and cost just as much. The ProHealth one is fabulous.

    3. I can add that I was taking cyanocobalamin and felt nothing, but switched to methyl and within two days noticed I no longer felt depressed (which has been a chronic condition). So I am inclined to believe that the methyl form works better. But I wish there was some scientific investigation done that Dr. Greger could report on because I’ve read that you need a higher dose of methyl over cyano and I would like to know that I’m taking the correct dosage.

      1. When you say methyl, do you mean hydroxo or just methyl because I was reading that methyl alone isn’t sufficient in preventing B12 deficiency according to this study: Thakkar, K.; Billa, G. (2015-01-01). “Treatment of vitamin B12 deficiency-methylcobalamine? Cyancobalamine? Hydroxocobalamin?-clearing the confusion”. European Journal of Clinical Nutrition 69 (1): 1–2. doi:10.1038/ejcn.2014.165. ISSN 1476-5640. PMID 25117994.

      2. I may be wrong but I don’t think you’ll find any medical research company recommending a pure natural product over a synthasized one. It’d be like the ice cream man telling you his ices are no good and full of too much sugar.

  6. I think the point for not just vegans but for anyone who is health conscious is to choose healthier foods and to remove as many synthetic products from your body as possible. It maybe fine for others to take in Cyanide if they choose, more power to them… but lets not take away all our healthy choices simply because its cheaper…Has everyone gone mad with the money bug….If its not naturally found in my body why put it in there?……
    Cyanocobalamin when digested becomes methylcobalamin then leaves the cyanide behind.. although at none toxic levels, but can bioaccumulate….
    Methylcobalamin is a very good and benificial source of B-12 although a bit more expensive..but it can be synthisized by chemically processing Cyanocobalamin..
    they just mimic human digestion..this way you can get B-12.. still get a good price and not get the cyanide…
    Hydroxocobalamin is natural.. and is the very best form of b-12 and very expensive… not only do you get the neurological benefits.. there are molecules in it that bond with cyanide in the body and allows it to be removed through urination..so just like all natural products it detoxifies..and does not toxify the body

  7. With this in mind, we can check out the various nature made vitamins that could possibly give us the exact vitamins that we may be lacking in. These natural vitamins can boost our immune systems, give us our Daily IU of Vitamins A, C, D plus B complex and other vitamins that we could need.

  8. If you have the genetic mutation mthfr, any b12 other than methylated turn into cyanide. My son has this ans we give him methylated b shots.

  9. My mom’s only got one kidney left that only works for 30% but I got her into taking this form of B12. Should she stop taking it and start using another one?

    1. Hi superape. Since kidney disease can result from several causes, the type and amount of B12 should be closely monitored by her MD. I say that not to dodge your question but since people with kidney disease have limited kidney function, taking high doses might allow unhealthy levels of the vitamins to remain in the blood.

      1. Thank you very much for answering my question Jacquie! I told her that maybe she needs to take another type of B12 and she´s going to ask her nephrologist. I will also tell her to ask him about the right amount ’cause I told her to take 1000 mcg a day as she is 66 years of age. Really thought I was doing the right thing for her… Thanks again! It’s much appreciated :)

  10. Hi Dr. Greger,

    I have been vegan for the last 2,5 years. Two month ago I decided to take a daily dose of B12 (methylcobalamina spray) to supplement my nutrient intake.

    I noticed that my lips have become chapped and dry and for the last 3 weeks an acne like rash is bothering me.

    Do you think these could be the result of overdosing with B12? Or that I show an intolerance to the product?

    Wikipedia says B12 overdose could lead to acne-like rushes:



    1. Hi Ioana,

      I don’t know how much B-12 you are taking but the body only requires 5 micrograms a day. That’s right micrograms not milligrams. Nobody makes dosages that small. So if you just take one pill a month of any brand you are getting all you need. And that assumes you are a strict vegan and have been for at least three years. If you are eating any meat at all you probably don’t need to supplement your B-12. My source on this is Dr McDougall.

  11. Hola Dr. Greger. I would like to know your thoughts about B12-cyanocobalamin injections (1000mcg). Is it true that it is a better way to make sure you are absorbing the vitamin?

    I already started taking it. One inyection a day per one week, one a week during one month and one per month to mantein the levels.

    I didnt find anything about inyections in your videos or webside and really would like to know what you think about it. Thank you for everything. Greetings from Spain!

  12. Our unless you strive for an actual healthy lifestyle! Cyancobalamin being the most widely used form dies not make it the safest form. I seek nothing. I am a SAHM mother of two that actually researches what I put in my body and in that of my family. There is plenty of information from various sources, including the encyclopedia, concerning cyancobalamin. It does not occur in nature, and for me that’s the biggest red flag there is. The fact that a medical professional would actually recommend cyancobalamin over other safer, more natural forms disturbs me greatly. Do your research- there’s a reason why ‘side effects’ are listed for cyancobalamin and not for other forms.

    1. methyl cobalamin is ‘ready-to-eat’ by the body. Other forms need to be first transported to the liver to have the CH-4 (methyl group) added, then released so it is ‘bio-available’.

      1. Actually Hydroxycobalamin is the most bio-available form, as Methylcobalamin gets converted to Hydroxycobalamin in the body, though the Methyl component is needed for multiple reactions within the body anyway (ie: it is good, not a waste product). Also, for those with too much cyanide in the body, Hydroxycobalamin will combine with cyanide molecules, and allow it to be excreted via the kidneys. Thus, it is used in cyanide poisoning cases.

        Many people with heavy metals in their bodies, and other toxins that over tax the liver, cannot easily convert Cyanocobalamin to Methycobalamin, so the Methyl version is preferred. It is also preferred over Cyanocobalamin if you are wishing to follow studies showing that doses of 10000mcg are required to get the higher energy results desired, as well as for those with low B12.
        At higher doses, Cyano version would give you significant levels of Cyanide which would further tax your liver, and is poison, period.

        Hydroxycobalamin is best intravenously (in terms of bio-availability), but needs an anesthetic administered with it, as it “burns.”

        Overall, from a cost and health perspective, orally, methylcobalamin is probably the ticket, and if sublingual, has been shown in studies to be just as effective as shots of B12. It can be bought at most Sams and Costco’s at the most affordable prices I could find readily available anywhere for high-dose Methylcobalamin.
        I can also state that it has proven nearly miraculous results for me with seasonal allergy relief. Check out B-12 and how it naturally suppresses immuno-over-response, if you have bad upper-respiratory allergies…not a permanent “cure,” but lowered my spring allergic reactions to nearly nada.

  13. I assume you also take the potentially poisonous folic acid instead of a more bioavailable form of folate that won’t potentially build up in your bloodstream like homocysteine, causing the same problems? Cyanocobalamin is about as bioavailable as the iron in nails, since your body has to strip the cyano-complex off and add the methyl to use it.
    Do us all a favor and chew on some nails…

  14. Hi Dr greger, the cheapest b12 supplement I could find already has b1, b2, b3, b6, c and calcium pantothenate in it. Is that okay? It costs around 2 cents per tablet

  15. I think everyone should read the following website that compares the three types of B12 in a succinct, but very informative fashion. My conclusion has been that methylcobalamin is the best choice for many reasons, including that it is a methylating agent, decreases homocysteine, and does not deplete glutathione as both other forms can. But toxicity is also a major concern. Cyanocobalimin is inferior when it comes to absorption, toxicity, GSH depletion, dependence on intrinsic factor, and more. This article is very well referenced.

  16. If you get your genome mapped by 23andme and run it through knowyourgenetics.com engine, the proper form of B12 specifically designed for your genetics will be shown on page 16 of the resultant MPA report. So while I was supplementing with MTHF folate for my MTHFR defects and some types of B12 (I think I found a supplement containing all types of B12), once I changed to the two forms recommended for me by that table that takes into consideration your heterozygous and or homozygous mutations of COMT V158M and VDR Taq, my recommended types were hydroxy and adenosyn, and I tell you it made a WORLD of difference to me. Same with husband who had cognitive difficulties (misdiagnosed with Alz, but probably was simply a B12 deficiency). Once I got him on the right types which was basically all types plus more Methyl, it made a WORLD of difference for him.

  17. Hi Dr. Greger,

    What about people who have the MTHFR mutation? Wouldn’t methylcobalamine be the best option? I am just curious because I recently found out that I am heterozygous for one of the MTHFR mutations (SNP). On that subject, I would really enjoy a blog post or video about this mutation because it does have far reaching implications in nutrition, and there are quite a few people that have these SNP in the MTHFR gene and sadly most of our doctors don’t really know what to recommend as far as proper detoxing, supplementation, etc. Just thought it would be an interesting read or watch coming from you!

    1. That’s interesting. My wife and I take the same B12 supplement, but my serum levels are much higher than hers. I wondered if it could have been genetic (or if the test was just badly done). Have you had your B12 tested?

    2. My husband has this mutation too. The Hematologist & Neurologist have him taking Rx Cerefolin NAC 1x/day (Folic Acid 5635mg, B12 1mg, B6 50mg, B2 5mg) and 1 injection monthly (the first few years was weekly) of 1000 mcg/ml Cyanocobalamin. What they explained to us was that mutation does not allow the body to convert food (vit B’s) to a form he can utilize. Hence his off the chart Homocysteine levels, heart disease and seizure disorder….now all under control.

  18. The different forms of B12 are not alike. Cyancoblamain converts to hydroxyl which converts to methyl and adenosylcobalamin. Adenosyl is the only form stored by the liver. Hydroxy has a longer half life than the other forms. BUT, even more important is there is a combination of B12 that is right for you based on your genes. If you run your 23andme.com genetic results through the engine at knowyourgenetics.com, you will receive a Methylation Pathway Analysis, and in the middle of that (page 16 or so) is a table that
    recommends the different forms of B12 for you depending on primarily two genetic mutations COMT and VDR Taq. I am a no methyl person, and I could really tell the difference when I started supplementing with just hydroxy and Adenosyl B12 forms. My husband is a methyl person and does better with primarily with half Methylcobalamin and half all the other kinds. Helped him with cognitive problems, memory, energy and me with depression, energy, outlook. So Dr. Gregor’s analogy to the coral calcium scheme is simply dated. Nutrigentics is a new field and any doctor that isn’t getting on board is not your best bet. Encourage your doctor. Info on how to use the 23andme data to generate useful reports to aid your health can be found on the Armchair Genetics blog on mthfrliving.com. Good health and God Bless!

    1. Do you or your husband mix the different forms to together/take together in one ingestion? Or does methyl need to be taken on one day, other B12 forms on other days? Thanks.

  19. Dr Greger recommends cyanocoblamin B12 supplements “unless you’re a smoker, have kidney failure…etc” I have been a vegan for just under a year and I have mild stage 2 kidney disease. Therefore, should I avoid cyanocoblamin and invest in the methylcobalamin or another form of B12?

  20. This is the information I have regarding B12.

    Deficiency can be serious, so its convenient to take a pill.

    Absorption rates go down on megadoses (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2532799/table/T1/#TF1-4

    so, you have to do the math.
    Cyanocobalamin is a lot more studied than the others (and proven efective). It’s also very stable. It has a little cyanide, but that is no problem for the body unless you have serious disease.
    Methylcobalamin is theoretically better once in the bloodstream, but is very unstable. There are some studies that prove some benefits (as a methyl donor) unrelated to B12 deficiency. As it is very unstable, doses need to be higher.
    So, cyano is a safe bet. Methyl seems better but it is unstable (not so reliable) and not so well studied (there are some).
    What do I do?, I take 500mcg (micrograms) cyano and 1000mcg methyl alternating every two days.
    If I had any deficiency, I would take cyano.
    Nowadays, they are both pretty cheap…..

  21. What’s the “smoker” and cyanocobalamin problem? Does the smoker need more or less or a different form? I am not a smoker of tobacco but they have asked for clarification below.

  22. If this is true (and there is no difference between the cobalamins), why are other seemingly sincere (not greed-driven) people furnishing arguments for the superiority of methylcobalamin (e.g., i. Mike Adams http://www.naturalnews.com/032766_cyanocobalamin_vitamin_B-12.html; ii. ) – and how would Dr. Greger respond? I read that Japan only used methylcobalamin and that methylcobalamin does fantastically at ameliorating B12-deficiency-based brain issues where the others either underperform or do not perform at all.

    I think it would be really helpful if Dr. Greger made a video clarifying this issue.

  23. IF the RDA of B-12 is 2.6 mcg/day, WHY are over-the-counter supplements sold in sublingual tablets of 1,000 mcg?
    (The bottle I bought has B-12 as cyanocobalamin.) How often should one tablet be taken?

    ALSO: After reading ALL of these comments here from over the last 3 years, is there a definitive answer to the question:
    WHAT TYPE of B-12 supplement is most effective/safest/BEST?

    Thank you

  24. I started getting acne after starting on the cheap B12 supplement you recommended (from Nutra Bulk). I looked around and learned that this is a common complaint of people supplementing B12; but the people from Global Healing Center said they have not received *one* such report that their B12 (specifically methylcobalamin) has caused anyone acne.

    What’s in my B12 (not methylcobalamin) that is causing me to break out that isn’t in the B12 from GHC (Dr. Group’s Global Healing Center)? This acne can’t be a good sign.

  25. Dr. Greger, what would you suggest for me, a woman who wants to follow a plant-based diet (currently vegetarian), but has a cobalt allergy which prevents me from taking B-12?
    I’m hoping to get a second opinion about the cobalt allergy in the near future.

  26. If I take more B-12 a day a 3 a day 250 mig is that ok or can you take too much ? Also I am taking a 500 mg gel cap of omega 3 a day . I couldn’t find a 2500mig tab for once a week. how much is too much ???

  27. Methylcobalamin is superior B12. Plant foods are Methyl foods thus Methyl version is best! (study of cancer in twins (sharing same DNA) but one had cancer and the other no cancer showed it was due to eating a lot more Methyl (plant) foods!!!)

  28. I think most of you are worrying yourself about things that are really not fully understood yet. The best forms of B12 is what wworks for you. Listen to your body and get your bloods checked occasionally. Personally, I’m mainly plant based but I make a point of eating 2 or 3 portions of steamed clams a week. That is my source vitamin b12 ande I’m in good shape.

  29. On some internet forums, someone claimed that the sublingual variety of methylcobalamin vitamin b12 could cause problems for people who take it if the consumer happens to have mercury fillings in their mouth.

    Does anyone know if that’s true??

  30. Is there a hazard associated with taking sublingual methylcobalamin B12 if you have mercury fillings? I think I heard somewhere on the internet that this was not safe, but I wanted to check.

  31. Hi! love the book, the vids, the blogs and the attitude!!!

    I consider myself informed enough to have made the switch to a plant based, whole food eating regime and feel great for it…

    I’m concerned about vitamin b12 and as such have been looking at supplements. i understand Cyanocobalamin is preferred due to the fact that more studies have been carried out on it, however the supps i have found contain magnesium stearate. i am lead to believe that magnesium stearate is not safe however i cannot find any particular studies or info on this. can anyone point me in the direction of some convincing information from a credible source to help make a sensible decision?
    Really appreciate the service!!!

    1. If you are concerned about additives just go to a compounding pharmacy and get cyanocobalamin with just vegetable cellulose added.

  32. Hi Dr. Michael, I have a question regarding age spots (sun spots). I have looked at all your info on skin videos,but is there something I can topically do? I am a organic farmer,WAS a sun worshiper in my earlier years, but now use hats, natural sunscreen, Iam vegan and eat broccoli,collards kale,beets on a regular basis besides our own fruit,nectarines,peaches,cherries,blk berries,rasberrries fresh from the vine.And many more foods i grow. Is there any herb, lemon I can do?

  33. I dont understand nutritionfacts.org obsession with cyanocobalamin. Its pretty much a concencus that its not the optimal form of B12 to take. Hydroxocobalamin is the form that is most commenly found in food and it has other benefits compared to cyanocobalamin. Its also the form that is used for treatment of B12 defiecency in other countries than the U.S. This article with references explains it: http://www.b12-vitamin.com/hydroxocobalamin/

  34. The right type of B12 is an individual thing. There is no one-size-fits-all for any condition. It’s based on specific genes, but the various forms of B12 are inexpensive enough that one would benefit from trial or error if you didn’t want to run your genome and do a bit of legwork. here is a post about it that should be useful to this discussion http://mthfrliving.com/health-tips/supplementing-for-mthfr-b12/ For me, when I’ve supplemented with methylcobalamin, I have big anxiety all day. I will never ever use that or multi’s that have it. I use a combination of adenosylcobalamin and hydroxycobalamin. So there is no one answer to the right kind of B12 for any condition. It depends on who you are and your individual genes. Health and wellness to you!

  35. The recommendations that I have read in the literature is to avoid cyanocobalamin if your Glomerular Filtration Rate (GFR) is less than 50. Most people have no idea what their GFR is, but many walk around every day with GFR lower than that and do not know it. It has to drop below about 20 before dialysis is needed. Diminished kidney function allows the cyanide to build up to neurotoxic levels. But what is the simple fix? I have priced methylcobalamin on Amazon less than $5 for a two to three month supply, and their might be others that are cheaper. Why bother even testing or worrying if you can get it that cheap? The comment about vegan methylcobalamin is an interesting one. B12 is only made by bacteria and certain mushrooms. I suppose someone might spare the bacteria and only slaughter mushrooms, but that is taking it a bit far don’t you think? In short, I don’t know a source for mushroom only B12…

  36. My husband has had what appeared to be low-pressure glaucoma for years, but the medicines and treatments for it were mostly harsh and painful; none helped stopped the progressive loss of his vision. Then a doctor prescribed the methylcobalamin form of B-12. We look up all our medications online to get a full picture of what we are taking. I am not a scientist or doctor, but there seem to be some studies indicating that this form of B-12 has a beneficial effect on some forms of nerve disorders. Anyway, he gradually noticed that his eyesight was slowly returning. A second eye scan compared with the first one showed improvement in all areas except the black dead zones. The brown, dying zones, for example, had shrunk.

    He stopped taking it for awhile, and his eyesight began to deteriorate again. Currently he takes it religiously and his eyesight has stabilized. I know that this is anecdotal, but as another post said, it’s widely and cheaply available, and according to the studies I read, it does no harm. For what it’s worth.

  37. If one is plant-based, celiac, has both the MTHFR A1298C +/+ AND MTRR A66G +/+ (homo/double gene mutations), and has loss of sensation/numbness, what B12 should they take? Thank you!

  38. Omventure,

    I would encourage you to consider the methyl format and also check your other genetic marker for additional issues especially homocysteine levels. Because of the celiac and the decreased absorption, it would be appropriate to do additional testing, such as the Spectracell panel or ION testing (genova labs) to get a more comprehensive view of your nutritional status. Dr. Alan Kadish moderator for Dr. Greger

  39. In the parts of the world where very healthy long living people had plant based diets, how did they get enough vitamin b12 to live so tlong with good health?

    1. Serita Scott: Here’s my understanding: Even the traditional Okinawans ate 4% of their calories from animal products. They were primarily plant-based, but still ate some animal products. What’s more, we know that B12 is made from bacteria that live in dirty conditions like the lower part of human intestines. People can get some B12 from dirty vegetables or dirty water. It’s possible, it’s just not safe. NutritionFacts has a good article that puts the B12 issue into perspective: http://nutritionfacts.org/2011/08/25/vegan-b12-deficiency-putting-it-into-perspective/

      A quote from the above article : “So on one hand, there’s the possibility of eliminating the greatest killer in our country, which decimates the lives and families of more than 100,000 Americans every year, at an annual cost in the hundreds of billions. But, on the other hand, we risk vitamin what deficiency? Are the defenders of the status quo seriously trying to stack a documented cure for heart disease (not to mention the reversal of diabetes, obesity, and hypertension) against some obscure B vitamin?

      It’s true, plants don’t make B12. Animals don’t make it either. B12 is made by microbes that blanket the earth. These bacteria grow in the guts of animals, which is why their bodies and products can be a source of this vitamin. Our herbivore primate cousins get all they need ingesting bugs, dirt, and feces, and we may once have gotten all we needed by drinking out of mountain streams or well water. But now we chlorinate our water supply to kill off any bugs. So we don’t get a lot of B12 in our water anymore, but we don’t get a lot of cholera either—that’s a good thing!”

    2. I come from India and many people in the rural areas of south India wake up in the morning and consume hand pounded rice (Filled with nutrients, unlike the machine polished white rice) or millet cooked the previous night and soaked in water in earthern pots. The fermentation process is carried out by the bacteria in the air and in the soil of the earthern pots. B12 is basically produced by soil bacteria and by consuming a pot full of this fermented rice every morning, along with raw shallots (Sulphur) and green chillies (Vit C), they had no problems with Vit B12. Unfortunately, the urban India is obsessed with the western style fast and processed food and it is filled with people deficient in Vit B12.

      Here is a study on the B12 from fermented rice. http://www.drvasudev.com/mobile/Vitamin-B12-&-vegans.asp

  40. Thank you so much for your prompt and interesting reply. I have been vegetarian/organic for many years for ethical reasons but happy to find excellent health reasons to support my lifestyle. When I realized that the milk industry was responsible for the veal industry, I went off all milk and milk products. Probably if I give up my ignorance about the possible murder of roosters, I will walk away from free range eggs as well. Eggs are consumed rarely because I can only digest them when eaten rarely. I have moved over to goat milk, yogurt, and goat cheese because from all my observations goats are not mistreated or murdered in the prime of their lives. They seem to be pets with names and mow fields and copulate all day.

    By the way I am 77 and a half and in perfect health with no need for any kind of medication. This is probably due to both genetics and diet.

    My reason for eggs is B12 and perfect protein. My reason for consuming goat dairy products is to get vitamins B12, D, and calcium.

    Please comment on why it is okay or not okay to continue with the goat product. You can comment on free range eggs also though if I become convinced that roosters are murdered because they are noisy and people do not want fertilized eggs, then I will give up on eggs. In this case, I need to know how to make pancakes, waffles, breads an other stuff without eggs.

    The issues of vitamin B12, D, Calcium and other minerals have been a source of concern and confusion for me. Also why is taking a supplement B12 or D and calcium okay when other supplements are not. The word out is that no supplement actually does anything close to getting desired benefits one gets from food sources. Why is B12, D, and calcium different?

  41. Thank you very much for your prompt and interesting reply. I have been vegetarian/organic for many years for ethical reasons but happy to find excellent health reasons to support my lifestyle. When I realized that the milk industry was responsible for the veal industry, I went off all milk and milk products. Probably if I give up my ignorance about the possible murder of roosters, I will walk away from free range eggs as well. Eggs are consumed rarely because I can only digest them when eaten rarely. I have moved over to goat milk, yogurt, and goat cheese because from all my observations goats are not mistreated or murdered in the prime of their lives. They seem to be pets with names and mow fields and copulate all day.

    By the way I am 77 and a half and in perfect health with no need for any kind of medication. This is probably due to both genetics and diet.

    My reason for eggs is B12 and perfect protein. My reason for consuming goat dairy products is to get vitamins B12, D, and calcium.

    Please comment on why it is okay or not okay to continue with the goat product. You can comment on free range eggs also though if I become convinced that roosters are murdered because they are noisy and people do not want fertilized eggs, then I will give up on eggs. In this case, I need to know how to make pancakes, waffles, breads an other stuff without eggs.

    The issues of vitamin B12, D, Calcium and other minerals have been a source of concern and confusion for me. Also why is taking a supplement B12 or D and calcium okay when other supplements are not. The word out is that no supplement actually does anything close to getting desired benefits one gets from food sources. Why is B12, D, and calcium different?

  42. Thank you very much for your prompt and interesting reply. I have been vegetarian/organic for many years for ethical reasons but happy to find excellent health reasons to support my lifestyle.

    By the way I am 77 and a half and in perfect health with no need for any kind of medication and no structural problems. This is probably due to both genetics and diet.

    My reason for eating free range eggs is B12, minerals, and perfect protein. My reason for consuming goat dairy products is to get vitamins B12, D, and calcium.

    Please comment on why it is okay or not okay to continue with the goat product. You can comment on free range eggs also though if I become convinced that roosters are murdered because they are noisy and people do not want fertilized eggs, then I will give up eggs. In this case, I need to know how to make pancakes, waffles, breads an other stuff without eggs.

    The issues of vitamin B12, D, Calcium and other minerals have been a source of concern and confusion for me. Also why is taking a supplement B12 or D and calcium okay when other supplements are not. How is B12, D, and calcium pills different?

    1. Hi Serita, I am one of the moderators on the forum. Congratulations on your excellent health. Clearly you are doing many things right in addition to having great genes to start out with. As you know there are many reasons people avoid animal products. Ethical vegans cannot bear to subject any animals to abuse or death for their nourishment or clothing so they use substitutes. Some of the aspects of factory farming are really horrific if one gets into the day to day practices and easier to understand the ethical vegans point of view. Another ethical motivation is for the good of the planet since all animal farming practices use higher amounts of natural resources and create pollutants far beyond that of fruit and vegetable farming. You have to come to those conclusions on your own regarding how you feel about your place in the world and what sort of footprint you are comfortable leaving.

      Dr. Greger addresses these concerns in his writings and videos but I believe his primary focus is on the health aspect of food. Like most things in life there is a continuum. If you refer to his book How Not To Die you can see where disease and longevity is tied is to the amounts of what people eat. Very often strict vegans have lower blood pressure, glucose, heart disease, cancer and body weight in proportion to the amount of animal products that vegetarians, flexitarians, etc.. up to those that eat the standard American Diet. B12 is a concern, as you mentioned for the strict vegetarians as well as the elderly as they can lose the ability to produce intrinsic factor as well as breakdown the precursors of B12 in their stomachs. B12 is often prescribed as a supplement to vegans and non-vegans alike. I, too eat an egg on occasion figuring that it will give me some B12 as natural sources contain the molecular variants often missing in even the best supplements. As in all things it’s a personal choice.

      If you choose to omit eggs from here on out there are many websites and vegan cook books that can explain how to use the various egg replacers as binding agents in baked and cooked foods. They not only will rise and not fall apart but have a much lower fat and cholesterol level.

      I hope this helps to sort out your conundrum.

    2. The main difference between diary from goats (and sheep) and that of cows from a purely chemical basis is the casein. Cow milk is a different type of casein. It also contains dramatically higher levels of casein. (If I remember correctly, it’s at least 10 times more.) Then, as you say, cows often are given much more antibiotics and other immunizations as well as generally have a lot of pesticides in their grain. So, your choice for cheese or other dairy products from goats is a sound medical decision as well as an ethical one.

      Eggs are as contaminated as the chicken. So, a truly range-fed chicken that exists on natural scratch feed should produce a healthier egg. Keep in mind that a chicken farm next to an agricultural farm that uses pesticides will end up with pesticides in the chicken, though they’d hopefully be fewer or lower levels of toxins.

      On the issue of Vitamin D, I am lucky enough to live in a warm weather climate and get all my the vitamin D I need from the sun. If you eat enough calcium-rich foods, and are getting enough vitamin from 15 minutes of sun each day, then you don’t need those supplements at all.

      I’m with you on the B-12 supplement too. If it’s in the dirt that my vegetables grow in, and I eat my potatoes with the skins on; then, I’m surely getting enough of that trace amount needed to last up to a decade inside my body. The concern for me isn’t so much what else might be in my soil that could make me sick, but does my soil actually have what I need. When if doubt, people seem to err on the side of supplementing.

      Regards eggs and baking… I use applesauce or bananas as a substitute whenever possible for both eggs and oil in recipes. When that isn’t desirable, flaxseed and water make a nice egg substitute.

      Good luck to you.

  43. Hi Deborah. Hi! My name is Dr Renae Thomas and I am one of the medical moderators. I think the shot type depends on the preferred brand and your country. For example I have seen a lot of methylcobalamin in Australia, but I believe cyanocobalamine is more common. Cyanocobalamine is the most studied, and as such the one Dr Greger recommends.

  44. I’ve recently been diagnosed with Trigeminal Neuralgia and it’s been suggested to me to take B-12 in the methyl cobalamin form. I guess it helps with repairing the myelin sheath that coats the nerves. I’ve read through this entire thread and no one seems to be taking B-12 for nerve damage. Am I on the wrong track with B-12 supplementation?

  45. Sue,

    My personal experience is the use of either methyl or hydroxy cobalamin, in injectable form. In our clinic we use a mixture with other b complex vitamins and seem to see effect fairly quickly. One of the reasons we don’t use the cyano is the cobalt build up over time and most on the market are complexed with preservatives.

    Even conventional medicine has a prescription form, using B-12 for diabetic neuropathy…..http://www.metanx.com/ and don’t pay the inflated price !

    Dr. Alan Kadish moderator for Dr. Greger

  46. Dr. Greger, Dr. McDougall, in his latest newsletter (April 2017, https://www.drmcdougall.com/misc/2017nl/apr/b12.htm) says “. . . my recommendation has been to take a supplement of 5 micrograms daily. . .With amounts of a hundred times greater than needed, rather than taking daily, a safe regime could also be 500 micrograms weekly. . . My recommendation is to take the hydroxyl, methyl, and/or adenosyl forms (not the cyano form due to the toxicity from chronic cyanide accumulation). After taking any of the individual forms for three months you, should have your blood tested. A simpler and more certain approach would be to take a formulation that is already in a combination of the hydroxylcobalamin, methylcobalamin, and adenosylcobalamin.”
    Would you please comment, thank you !

  47. Dear Mdm,
    Dr. Greger is not able to respond to all of the comments on this site, and do all of the other things he does, which is why he has a team of volunteers like me to help him. I think that Dr. Greger has expressed his opinion on the subject of the various forms of vitamin b12 above, and in these materials:
    You are certainly welcome to take the advice of someone else, such as Dr. McDougall, if you like. While some experts may offer slightly different opinions on a few details, we all agree that a whole food, plant-based diet is optimal for health! I hope that helps!

  48. There are numerous sites that recommend Methylcobalamin but I trust Dr. Greger when he states that there are no studies that show the efficacy of any other form than Cyanocobalamin. I have doubts, however, after reading the comments talking about the toxicity of it. Is it safe or sensible to give infants and children a supplement that toxins in it?Maybe non-smoking adults can effectively detoxify the little amount of cyanide but what about infants and children?

    Thank you

  49. Hi and thank you so much for the tremendous work of science based and unbiased information you offer to people.

    I read recently this article with publicity and links to buy stuff:


    This article says that cyanide is toxic and is part of the Cyanocobalamin form of vitamins B12, and that in order to “flush out” this toxic “cyanide molecule”, the body will “use” the resources of the “methyl group” that are available, suggesting that the Methylcobalamin (that is produced by the body with the supplement of Vitamin B12 composed of Cyanocobalamin) will be “distracted” from its normal use (diminishing the toxic levels of Homocysteine).

    It seems nevertheless that Methylcobalamin compared to Cyanocobalamin is best assimilated by the body and directly available, but less stable, more expensive and less easy to absorb as a shot maybe required…

    Does the science has anything to respond to this “stealing distracting process” or lets say SDT, that is leading to recommend Methylcobalamin over Cyanocobalamin ?

    Does the supplementation with Cyanocobalamin an issue or not for vegetarian and other people ?

    To sum up, is it true and is it that problematic ?

    1. Ok, I respond to my comment for the sake of people sharing…

      This other link that I just found to answer my question, says that the level of cyanide contained in the vitamin B12 is not that of an issue, as broccoli does contain some too.


      So it seems it is true but not really an issue.

      Thank you to you OGFDMG (Our Great Friend Doctor Michael Greger ;-)

      Many blessings for changing my life and knowledge
      Wishing you the peace and love, the joy and wisdom

    2. Hautrive,

      I know this is weird, but cyanide is normally found in foods such as almonds, tapioca, millet, lima beans, soy, etc… If you eat more than 50 milligrams of cyanide, that can be dangerous. A 1000 microgram pill of B12 (cyanocobalamin) contains 20 micrograms of cyanide. Therfore the amount of cyanide in cyanocobalamin is considered to be insignificant.

      By the way, naturalnews.com isn’t really the best source of scientific information. For example, they seem to compare microwave to nuke and deny that HIV causes AIDS disease…

      Have a nice day!

      Adam P.

      1. Hi Adam, Thank you so much for your reply.
        I have some pills of Cyanocobalamin vitamin B12 that have a high dosage, like you said, and normally the usage is to take one every week or ten days, because of less efficiency of the assimilation for high dosage in one take. But it is good you informed me that it wouldn’t be very much healthy to have several at the same time. Thank you.
        I understand also that not everyone is as serious, reliable, generous and funny as our fellow saver Doctor M. Greger.
        May he be well and happy May you be well and happy Wishing you love and peace Patrick

  50. I have MTHFR, Lyme and a variety of soft-tissue, joint, neurological and gastro-intestinal problems. I really would like to work with a dietician or nutritionist who specializes in helping people find foods that do not make them sick when they have these disorders. Can you suggest someone in southern California?

  51. Can you suggest a type of coconut milk that does not have the artificial type of B12? They all seem to be fortified with B12. Those that mention the type of B12 say that it is the Cyanocobalamin.

    Thank you for having this wonderful discussion!

    1. Hi Roberta,

      I am a volunteer for Dr. Greger. Thank you so much for your question.

      Dr. Greger recommends cyanocobalamin (2,500 micrograms once/week). Dr. Greger does not recommend methylcobalamin because there is some research that shows that individuals deficient in B12 did not improve when taking methylcobalamin, but do improve when taking cyanocobalamin.

      The only people that may benefit from the methylcobalamin are those with the MTHFR gene mutation, where they are missing an important enzyme in the metabolism of vitamin b12. Unfortunately, I am not aware of the background behind the information provided behind Dr. McDougall’s recommendation.

      I hope this helps!

  52. Dr. Greger does not recommend methylcobalamin because there is some research that shows that individuals deficient in B12 did not improve when taking methylcobalamin, but do improve when taking cyanocobalamin.

    Could you please provide references to this research, thanks.

  53. I was a vegan, became B12 deficient, did not know I needed to take B12 – my stupid mistake, number was 80, was feeling horrible, fatigued, dizzy, tingling in toes, shortness of breath, hair falling out, leg and back pain. Doc said take 1,000 mcg of B12. Took Methyl B12 with folate and after two weeks started to feel great!! Two months later cut my dose down to 500 mcg of same supplement and last week started suffering from terrible neck/shoulder/head pain with a headache. I looked up to see if the vitamin had anything to do with it and sure enough, yes, it was probably the cause. I stopped taking the B12 and after five days the headache has subsided. I know that the Methyl B12 with folate was working as I felt SO much better and all my horrible symptoms went away but now I’m afraid to take it again. Any advice???
    Thanks so much!

  54. Hi Chris T., see these links to help answer your question. I would encourage you to obtain dietary folate from green leafy vegetables rather than in a supplement form. As far as B12, please see the second link regarding optimum nutrition recommendations. Might you consider a once weekly b12 supplement if you are following a strict vegan WFPB diet? Maybe this might help your symptoms. Best of luck.

  55. Hi Dr Greger,
    Words won’t be enough to describe how thankful I am to you for all that you do. Thank you.

    I have a question tough. I’m african and i do eat a good amount of cassava roots (mainly on the form of cassava flour and some cooked too) and also other roots (tubers) like yams.

    What form of B12 should I take? Since you don’t recommend it for cassava roots eaters.
    I do notice some twitching when i take cyanocobalamin supplements or when i’ve been taking them for a while and then skip it.

  56. I have skimmed this entire thread and here’s my frustration: What specific vitamin product to meet the preferred type of vitamin b12 is recommended. I just spent 2 hours on amazon trying to identify one, and I cannot decide because they all have added ingredients. I am overwhelmed with the choices. Can anyone help?

  57. if one has had kidney issues (gfr of 42), is being treated for hiv & cryptococcal meningitis with amphotericin & flucytosine…. should they then not take the cyno form of cobolomin b12, if so why?

    thanks for your time
    & super videos!!

  58. That’s a complex medical history and is best managed directly by your healthcare provider. That said, with all the B12 options and the theoretical risk of the cyano form, why not just take one of the other forms?

    Dr. Ben


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