Doctor's Note

This is the first of a five-part video series on B12, similar to the series I did on vitamin D where I delve into the derivation of my recommendations, found here for B12 and here in general. To put vitamin B12 in context, please check out Vegan B12 Deficiency: Putting It into Perspective. Tomorrow I'll identify the safest sources of B12. If you can't wait until tomorrow for your video-of-the-day fix, please feel free to check out videos on 1000+ other topics.

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  • Michael Greger M.D.

    This is the first of a five-part video series on B12, similar to the series I did on vitamin D where I delve into the derivation of my recommendations, found here for B12 and here in general. To put vitamin B12 in context, please check out Vegan B12 Deficiency: Putting It into Perspective. Tomorrow I’ll identify the safest sources of B12. If you can’t wait until tomorrow for your video-of-the-day fix, please feel free to check out videos on 1000+ other topics.

  • vjimener

    Hi! Are hemp seeds useful for vegan people? Do they have all the essential amino acids? Thanks

    • Toxins

      All whole plant foods contain the 9 essential amino acids, therefore complimentary foods are not required. Protein needs satisfy energy expenditures so if you eat whole plant foods, till your full, your satisfying your protein requirements. this is made clear in the paper Position of the American Dietetic Association: Vegetarian Diets.

      Also, check out Dr. Greger’s video on vegan protein status showing that vegans had higher circulating protein levels than omnivores due to reduced inflammation in the liver.

    • Michael Lanfield

      Is it really true that there are 9 essential amino acids in plants? I heard some sources say there are even 12 twelve. I am confused!??

  • MacSmiley

    Please make all your videos accessible on your YouTube home page by default, Doc. It’s the only way I can see them with my old Palm. And my old Palm is my only access to the web.

  • MacSmiley


  • Elvin

    Dr Greger: I hope you will say something about cyanocobalamin vs. methylcobalamin. In some places (the country where I live is one) the only oral B12 available is methylcobalamin, coming in capsules of 500mcg a hit. And then on the packages it recommends taking (over the course of a day) 1500mcg. Now, is methylcobalamin especially hard to absorb, or what? I only take 500 or 1000mcg a day. Enough?

    • Michael Greger M.D.

      re: cyanocobalamin (the inexpensive form) vs. methylcobalamin. Vitamin B12 supplements are so cheap to produce that supplement manufacturers try to come with all sorts of fancy ways to “add value” to products so they can make more money. The coral calcium scam is the classic example–how else can you charge $20 for a bottle of chalk? Likewise, unless you’re a smoker, have kidney failure, or base your diet around cassava root, cyanocobalamin should be fine. If it’s unavailable, then I would shoot for about 2,000 mcg a day of methylcobalamin.

      • BPCveg

        Sorry, maybe I missed something … what if you are a smoker, have kidney failure or base your diet around cassava root — why do these factors affect which form of vitamin B12 you should take?

        • Gary Yuen

          I have the same question.

      • MacSmiley

        2000 mcg daily? Are you saying that methylcobalamin is inferior? that it’s less bioavailable, not just more costly than cyanocobalamin?

        Dr Fuhrman’s Gentle Care Formula MVM has only 30 mcg. Do you mean it’s time for him to reformulate?

      • Strix

         I’m totally confused now :? So, since I’ve been taking the Methylcobalamin for years now, I should either start taking the cyanocobalmin or take 2,000 — thousand!! — per DAY of the Methylcobalamin??

        I take a 1000 mcg of Methylcobalamin about twice a week.

        Wow. Please advise!

      • JD Mumma

        My research indicates that the reason cyanocobalamin costs less is because it requires less processing than methylcobalamin. As well cyanocobalamin is more stable when exposed to heat and/or light which may also may also lower production and distribution cost.

        “Vitamin B12 is produced industrially by microbial fermentation, using almost exclusively Pseudomonas denitrificans and Propionibacterium species as described in Japanese Patent 03244376, then converting the natural vitamin B12 into the
        cyanocobalamin form by chemical processes including cyanidization followed by extraction and purification steps using organic solvents (as reviewed by Spalla et al., 1989 “Microbial production of vitamin B12″, E.J. Vandamme ed., Elsevier, London, New York, pp. 257-284; Schliwa et al., Proc. Natl. Acad. Sci. USA, 1981, 78, pp. 4329-4333). The chemical conversion step and any subsequent purification steps cause this production process to be expensive, unsafe to the operators and environmentally unfriendly.” Hendrik Louis Bijl

      • Michael Lanfield

        Why so much, if our bodies only utilize up to 7mcg daily?

        • Toxins

          Its to spread the amount used over a weeks time.

      • barbarabrussels

        2,000 mcg a day of methylcobalamin? Could you please do yet another video on B12, particularly on this methylcobalamin type? I’m confused, I also have been taking 1000 mcg twice a week like the other commenter Strix has, based on your recommendations. This is insufficient for this type of B12? Almost all the supplements for sale contain this type, so lmaybe it’s worth clarifying. Thanks doc.

        • David Johnson

          Now I am wondering too. Dr. Fuhrman’s current multivitamin for men contains only 100mcg per day. It would seem this is greatly deficient, and that is alarming.

          Why is so much methylcobalamin required? Does Dr. Gregor explain this anywhere? it would be a great help if he would (or know where he has).

          • Joseph Gonzales R.D.

            B12 is super important. Adults needs roughly 2.4 micrograms per day, so 100 mcg is plenty. In other supplements it comes in higher doses. Here is the cheapest source of B12. If interested, check out more on Dr. Greger’s Optimal Nutrition Recommendations.


          • mbglife

            Hi Joseph
            Could you please help clarify all these questions on why the difference in recommended daily amounts of methl vs cyno complained? I have the same questions.

            Mark G.

          • Joseph Gonzales R.D.

            Absolutely, I explain more in detail. Check out my comment on B12 for tons of information. Let me know if it has the answer?

          • mbglife

            No, sorry. What I want to know is
            (a) what is the preferred form of B12 and why?
            (b) why is there a difference in the recommended levels?

            Also, I notice on the same page in response to a comment you posted, there was this post and I don’t know what it means. Is it saying that methyl is better or not? (Maybe just answering the above questions is the bottom line and all that’s needed.)

            William Hiatt’s reply to Joseph Gonzales R.D.
            a month ago
            “our methy ls 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”

          • mbglife

            I also found this reply by Laloofah on a different page. Is what she shares correct?

            (4 months ago)
            I’m about to re-stock my Vitamin B-12 stash and wanted to learn 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 differences, efficacy, safety, etc, of 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.”

  • bsmithson

    There are 2 items I am seeing called for in cookbooks, and I’d like to know if they are harmless. One is baking seitan in aluminum foil. Is there any transfer of aluminum into the food? And the other is liquid smoke. I had heard that this was mutogenic. Is that true? If so, could you please give me some idea of the risk? I think it is an ingredient not just in recipes, but also in vegan bacon and ham.

  • Lindsey

    I’m a vegan of 4 years (I supplement B12), and I just had my B12 serum levels checked, and they were at 1900 (don’t know the units) where the max end of the normal range is 900. Do you think it is necessary to get my homocysteine and MMA levels checked as well? Or since my serum level is so high, am I probably OK?

    • DrDons

      With those values you are fine. No need for testing of homocysteine and MMA levels.

      • brok

        Unless you have a genetic disease but you would know that by now

  • BPCveg

    Dr. Greger: Like you, I was also surprised to learn that the RDA for vitamin B12 is based on an obsolete study. I think that a great future addition to would be a section which provides the latest on RDA recommendations together with sources on which they are based. It would be useful to users of your website to be able to look up any nutrient/supplement (e.g. calcium, vitamin D, etc.) and find the corresponding source information that describes how the RDA was determined. When new studies are published that challenge the RDA, you could then indicate the updates directly on that section. I think that this addition would be a great enhancement to your website.

    • Toxins

      I second this idea!

      • Thea

        Yes, a great idea!

        I’ll add my twist: I want a link at the top of the page, right next to “videos, blog, about, …” that takes us directly to Dr. Greger’s latest recommendations (which may or may not relate to RDA) – with links on where those recommendations come from. Right now, if we want a summary of Dr. Greger’s recommendations, we have to hunt for the blog post on it, and I don’t think that post gets updated at these new findings come out.

  • Thea

    Dr. Greger: I have been following your advice about vitamin B-12 by taking a weekly sublinguil (sp?) pill. While the vitamin B12 daily recommendations have changed, have the weekly recommendations also changed?

  • Elvin

    Dr Greger: Since then, for one reason or another (non-availibility of cyanocobalamin being one them), there are those that have no choice but to take methylcobalamin, would you be so good from now on as to include methylcobalamin dosage in your Optimum Nutrition Recommendations?

  • Yaron

    Thanks for the video!

    If I’m not mistaken Vitamin B12 was first discovered 60-90 years ago. One can say it is relatively recent. What if there are more vitamins that we are not yet aware of?

    Is it possible that there is another vitamin, call it Vitamin X, that we still haven’t discovered and vegans might need to supplement their diet with? How can we be certain that this is not the case and that we don’t actually harm ourselves somehow following a vegan diet?

    I’m a vegan and actually not worried about it at all. There were many vegans who reached old age. I am asking the question out of curiosity alone…

    • Daniel

      Yes it could be so, but even if vegans consume less of this vitamin X, it could be so that the vegan body uses it less (like in the case of Zinc).

  • albert

    Dr. Greger can you please do some videos on homocysteine lowering. Seems like an important stuff yet couldn’t find much info here. I’d really like to know what your advice would be (yeah, “eat greens, avoid animal foods” ;)), but wouldn’t mind some details esp which food in particular was proven helpful

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  • Michael Lanfield

    I am confused Michael. In this video you said the excess B12 we pee out, but everywhere else I heard B12 stays in our bodies for a long time, like some 20 or 30 years. What is the verdict? Thanks! btw I love your work…

    • Toxins

      We absorb 1.5 mcg plus 1% of the original dose and everything else is urinated out. If we took a 500 mcg dose, this is the math that follows.
      1.5 + .01(498.5) = 6.48 mcg total absorbed.

  • Michael Lanfield

    Doesn’t cyanocobalamin contain cyanide? Then why does Greger recommend cyanocobalamin and not methylcobalamin?

  • NotYetAVegan

    Twinlab brewers yeast has a single ingredient, debittered brewers yeast. Each single tablespoon has 33% of the daily value of B12 (2mcg) according to the package. The package claims that it is also naturally occurring. Would taking 3 to 4 tablespoons of this throughout the day satisfy the B12 needs of a vegan? Or is this B12 not useful, like the type that comes from algae?

  • Scott

    Dr. Fuhrman pointed out to me (via his forum) that the recommendation of 4 to 7 mcg / d of B-12 in the 2010 study is INTAKE, not ABSORBTION (my emphases).

    So, on what basis is Dr. Greger building a case for 4 to 7 mcg / d absorbtion?

  • lea

    I am new ( 5yrs ) to being a vegetarian and Is there any truth that the B12 shots are better as it goes straight to the blood stream rather than the tables because those are water soluble and we pee most of it out? This is what a cardiologist told my friend after coming in for heart palpitations and was very deficient in B12

  • Antonio Sal

    Hi Mr. Greger, thanks for your advices. I wonder if B12 excess is bad: the graphs shown in the video show that above 7 mcg the levels of MMA and homocysteine start to rise. Does the body know to “stop absorving” when it’s fed up of B12?

  • The Vegan Junction

    Thank you for sharing this information!

  • Sara

    Hi Dr Greger. Can you please advise us or make a video on when to start supplementing b12 in babies and children and how often to supplement per age and dose. Can you also please make a video on plant based diets for babies and children.

    • Joseph Gonzales R.D.

      Hi Sara. Thanks for reposting. Here are all the videos we have on children. Here is a factsheet on feeding infants with B12 requirements, which may help. For more information you may consider checking out the Vegetarian Resource Group and their links to children and infant nutrition. I’ll let Dr. Greger know about your request. Thanks!

      • Sara

        Thanks for the info. Once the babies don’t want breastmilk anymore, how do you supplement B12? I am still feeding my twins at 11 months old 3-4x daily and 1-2x during the night. I really hope Dr Greger makes a video on this topic as I want to know if what I am doing is correct.

        • Joseph Gonzales R.D.

          We’ll see if he can do a video on this thank for the suggestion! In the meantime, check with your doctor about B12 supplements for babies. Note this is super duper important and I cannot say enough for B12 for those who follow a vegan diet. Children 1-3 yrs old need 0.9 micrograms of B12 per day, and kids 4-8 yrs old 1.2 micrograms per day. That is easy to obtain just assure they start supplementing post breastfeeding, and that you are good B12 stores and are supplementing as well :)

          • Sara

            Thanks Joseph! I supplement every few days with b12 and my levels are adequate :)