Vegan B12 deficiency: putting it into perspective

Vitamin b12 deficiency

When CNN’s  documentary The Last Heart Attack premiered—documenting Bill Clinton’s attempt to reverse his heart disease through diet—pundits were eager to point out the downsides. Yes, eating a healthy plant-based diet may make us “heart attack proof“—but, some ask, what about vitamin B12?

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!

So in our modern, sanitized world those eating plant-based diets must ensure a regular, reliable source of vitamin B12. I talk about the potential consequences of not doing so in my videos here, here, and here. In fact, I’m going to spend the next three days (starting today) rolling out precautionary-tale videos highlighting the importance of B12 supplementation for those eating otherwise optimally healthy diets.

Make no mistake: vitamin B12 is important. But so is keeping our perspective, given the millions who are crippled and die from the onslaught of chronic disease that could be prevented, stopped, and reversed with a B12-fortified, plant-based diet.

-Michael Greger, M.D.

Image credit: SMI Eye Tracking / Flickr

Other blogs about B12:
Vitamin B12: Are You Getting It?
Comments on Doug Graham’s B12 Statements
Response to: Vegan Vitamin B12 Deficiency is a Myth

  • What would you recommend as far as the best way to get B12 vitamins into our system, supplements? Will any over the counter supplement do?
    If one were lacto-ovo vegetarian, do they get vitamin B12 from cheese and eggs?

    • Michael Greger M.D.

      I’m so glad you asked! In my opinion, the easiest and cheapest way to get our B12 is to take at least 2,500 mcg (µg) cyanocobalamin once each week, ideally as a chewable, sublingual, or liquid supplement (you can’t take too much–all you get is expensive pee).

      Or, if you’d rather get into the habit of taking something daily (instead of once-a-week), I recommend at least 250mcg (I know the math doesn’t seem to “add up” but that’s due to the vagaries of the B12 receptor system–I’m going to post a video on how I arrived at these recommendations soon).

      Or, if you’d rather get it from B12-fortified foods, I’d suggest three servings a day, each containing at least 25% of the “Daily Value” on its label (again, I’ll explain). Such foods can be as exotic as a certain type of “nutritional yeast” or as simple as a bowl of Cheerios.

      As I’ll show in my video on Saturday, ovo-lacto vegetarians are also at risk for deficiency. Eggs and dairy are not good sources of vitamin B12 (in part because foods come as a package deal and eggs and dairy bring along as baggage saturated fat, cholesterol, and hormones).

      • elise

        Hi Dr. Greger – I was at VegFest today in Boston. Thanks for the talk!
        I’m curious why your recommendation is 250 mcg of B12 per day for vegans. This is *much* higher than recommendations I’ve seen in the past (e.g.:

        Thank you for your input!

      • Healthcare India

        I would like to thank for providing this great knowledge, because its great resource to me.

      • sf_jeff

        My option is a dropper-full of 10,000% in my juice that I make for a few weeks. Agree?

        • Joseph Gonzales R.D.

          Hi sf-jeff. I am not familiar with droppers. Please check with your doctor for a better answer than mine :) I would assume droppers of B-12 will suffice.


  • I have a problem with nutritional yeast, I sprinkle that on everything I eat! Is it possible to overeat nutritional yeast?
    Thank you for recommending a supplement and how much we should have. I also notice that even cheerios have it fortified with B12… that’s awesome you brought that up, because its so simple!

    • Massimo

      If it were possible to overeat nutritional yeast, I would have died long ago ;-)

    • Tonya CatLady

      Be sure to eat those cheerios with a plant based milk like almond milk, or coconut milk, or soy milk, or hemp etc. NOT dairy milk, NO cow milk or goat milk!!. As the doctor says…lots of baggage with milk like it can lead to osteoporosis and cancer. Fact!

    • Mergle

      you might want to avoid Cheerios since they will be full of gmo’s, pesticides, preservatives and fluoride, which is a neurotoxin! just get a b12 supplement and eat a little red star yeast.

  • Sujatha

    Hey Michael. This might be a weird question, but do you know if the recommendations are higher for people who drink alcohol?

    • Michael Greger M.D.

      Please see my response below.

  • MsAdventuress

    Excellent points! SO glad you have the argument laid out into a logical discussion, so we can learn and share with others (while remaining calm and peaceful). :)

  • sylvia

    I read an article that says to avoid cyanocobalamin and to take only methylcobalamin. What do you think about it?

    • Michael Greger M.D.

      Please see my response below.

  • lbateman

    Oh, I’d also like your knowledge about methyl B-12 apparently being better absorbed than the cyano kind–thanks!

    • Michael Greger M.D.

      Please see my response below.

  • shawnette

    You speak about vegetarians and vegans what about 100% raw vegans I would assume that because our meals are plant based that our b12 levels should be maintained. I have been getting monthly shots of b12/folic acid and take two dropper fulls of b12 however I am winging myself off of the supplements with the hope of not being dependent on supplements.

    • Michael Greger M.D.

      Please see my response down below.

  • It should be stated that titamin B12 ,Folic acid and Pyridoxine have a central role in cell growth and energy production and have given rise speculation that these vitamins may increase the promotion of carcinogenesis and enhance the growth of cancer cells at high doses.

    Folate and colorectal cancer: an evidence-based critical review
    Folate and cancer: timing is everything.

    More on the possible dual role of B12 and carcinogenesis:

    Theoretical involvement of vitamin B6 in tumor initiation
    The inhibition of some cancers and the promotion of others by folic acid, vitamin B12, and their antagonists
    Role of vitamin B12 and folate in carcinogenesis
    Vitamin B6
    Vitamin B-6 deficiency enhances end-organ sensitivity to steroid hormones

    • Michael Greger M.D.

      I replied to you down below–thanks!

      • Eddie Joel Gonzalez

        Michael I can’t find your answers down below (NEVER MIND I DID FIND THEM) thanks :)

  • Everything in moderation right?
    I read that Beer is a good source of vitamin B12 and folic acid. I drink a beer a day. Beer contains vitamin B6 which protects against heart diseases by preventing the build-up of a compound called homocysteine. Beer has a thinning effect on blood and prevents formation of clots, which cause blocks in coronary arteries. Moderate beer consumption also reduces the risk of inflammation, the cause for atheroscleros.

    • Michael Greger M.D.

      I replied to you down below.

  • Michael Greger M.D.

    It is so wonderful to see such a lively discussion–keep it up! Here are my thoughts on the above much appreciated comments:

    Vas Bouras: I’m afraid you’re thinking of of some of the other B’s. Thanks to yeast, beer has B3 (niacin), B5 (pantothenic acid) and B6, but sadly there is zero B12 in beer :( But, beer is a plant food, and as such has phytonutrients such as isohumulones, responsible for the bitterness from the hops that may have “beneficial effects in diabetes and obesity.” As you say, though, don’t overdo it. Folks may want to check out my video on the overall risks/benefits of alcohol consumption. Oh, and regarding your nutritional yeast addiction (which I share–it’s my fave air-popped popcorn topping!) shake away! All you’ll get is yellow pee (from the riboflavin :).

    Benjamin: Welcome back to the site! I added links to all the papers you cited if people want to check them out, but they don’t appear to support your contention that B12 may be carcinogenic. In fact the opposite may be true. Check out Vitamin B12 and Health, which suggests that B12 may protect against chronic diseases–including cancer. In terms of the folate, if you want, please repost your comment under the Can Folic Acid be Harmful video and we can continue there. Thanks for taking the time to offer your thoughts!

    shawnette: You are absolutely right that the raw food community appear to be at high risk for vitamin B12 deficiency, especially because (for good reason in most cases!) they avoid processed foods such as breakfast cereals, which is a common source of B12 (better than meat). Because we live in such an unnatural world, there are some supplements we may need to take, such as vitamin D (after all we’re not running around naked outside all day in equatorial Africa any more) and vitamin B12.

    sylvia, lbateman, and richbb: 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.

    Thank you MsAdventuress for your kind comment, and Sujatha, not weird at all! I wouldn’t expect B12 needs to be any higher in drinkers, but the test for one’s serum B12 level might be even less helpful than it already is (urine MMA is preferable), since liver damage can release B12 into the bloodstream and mask a deficiency by artificially inflating the measurement.

    If you’re viewing this before I’ve had a chance to respond to the rest, please check back. I’ll have them all done by tonight–I promise!

  • richbb

    I’m interested in your comments on cyanocobalamin vs. methylcobalamin like a previous poster.
    Your thoughts?

    • Michael Greger M.D.

      I got you covered! See my comment immediately above.

  • Thanks, when I get a moment I will reference the specific excerpts that are relevant to my concerns. That being said, I still supplement. Please everyone remember to take your B12 with the biggest meal of your day (ditto for vitamin D)!

    • Michael Greger M.D.

      According to the NIH, no need to take with food–anytime is fine!

  • sylvia

    Just by curiosity, why smokers and those having a cassava root diet the exceptions for taking cyanocobalamin? (For kidney failure, I think I can understand why). Thanks for your answers :)

    • Michael Greger M.D.

      The tiny amount of cyanide in cassava root and tobacco smoke may lead to tissue levels high enough to prevent the conversion of cyanocobalamin into the useable form (or at least that’s the short easy answer :).

  • adamtgardener

    What a great site!!!

    You make the comment that B12 is made in the guts of animals. What about us??? Are we not a biological life form similar to yet uniquely set apart from the “animal kingdom”? While I advocate anything that works to make a person more and more “healthy” it is with unequivocal clarity that I say not only can humans create B12 in there “guts” but it is wired into our DNA/RNAj to do so.

    Making the assumption that this could even be possible (in spite of all the studies that show otherwise), how would a person go about creating the conditions in the human body necessary to become a living B12 “factory”? Now there’s a study worth participating in and funding. What we need are volunteers (guinea pigs) to experiment upon.

    But wait. I know of one such hapless Soul that has already ran his own experiment. And what a “ride” it has been getting to this point. I have learned how to be…in cooperation with the plant kingdom…a geneticist, surgeon, hygienist, microbiologist, herbal formulae affectionado…all lumped into a category I term the backyard, life-science, human-science,research scientist. It’s the most rewarding “hobby” I could have ever engaged.

    I have had colon cancer healed, kidney stones removed painlessly, fibromyalgia disappear, rheumatoid arthritis “leave” and an extreme bout of blood sugar imbalances vanish. I have “watched” as a difficult type of jaundice has been “taken to task” and whose symptoms are now almost completely gone (yellowing of the hands, deep yellowing of the feet and legs below the knees [worse on the right side than the left], toenails on the right foot being restored to their original pink, vibrant life, the yellowing in the iris of the eyes almost all gone).

    I have “watched miracles of healing” take place by eating only from the Graces given through the organic, plant kingdom of life. Food is medicine and I have never tasted medicine this good in the “life” that proceeded the new life I have lived for the past 24 years.

    Way to go doc!!! You are one in a billion and I love your site. Very balanced so main stream America can see something for real. I am excited to listen to the documentary. It was such a sad, pathetic Barbara Walters Special to watch all these American icons applaud the “great surgeons” and “great technology” of mankind when there is no greater science than the Infinite Origins offered through the plants. I loved that Bill Clinton “squeaked in” the comment that if caught soon enough diet alone can heal heart disease. Way to go Bill. To bad corporate america can’t “heal” its’ greed and misinformation.


    • Michael Greger M.D.

      Thanks so much for for your great question! The bacteria in our large intestines do indeed make large amounts of vitamin B12 but it’s too low in your digestive tract to be absorbed so we end up just flushing it down the toilet :(

      • adamtgardener

        Thanks for the link to the study under too low.

        I come from a place inside me that says the DNA/RNA of human biological life forms has “perfection” written within its’ Ancient Scroll for human life. Every “cell” in my own “matrix” cries out that human DNA/RNA did not come into existent over billions of years…by “accident”. With that said…

        It is my personal quest (and Experiment) to seek out the conditions necessary (diet, breathing, fasting, juicing, etc.) to activate or “heal” the organs and systems of my body that had been compromised in eating by the traditions of my parents, their parents and their parents before them. You know the statistics…at least 75% of our health care costs are preventable. In other words we created our own disease through ignorance, arrogance or defiance in the face of genetic laws that say humans should eat this…that…and could be much more “healthy”. So far the success of my endeavor has been of a “hallelujah nature” (pun intended).

        If I may continue, the debris in my colon that has long passed from me and the persistent “soreness and aching” in the ascending colon that left after doing three months of liver and kidney “cleansing” have completely reformed my bowel into an organ of digestion and assimilation that is unheard of in any scientific journals or papers.

        To say that a study of individuals on a “similar” diet is to say once again that it is “impossible” for the human body to live whole creating what it requires to be free of disease. This is not my experience and it continues to unfold in dramatic ways.

        Physiologically the large intestine does indeed absorb water in its processes through the lining of the colon. B12 being water soluble is certainly going to be part of that solution. Is it enough for me? That’s the $64 question. With that said I will look one more time at the symptoms for B12 deficiency and seek out a supplement if the truth of that shows itself.

        But my colon has become an organ of incredible intelligence beyond anything I knew previously. Where it was once a “dumping ground” for dead animal carcass after carcass…ice cream cone after ice cream sundae…it has now become an “incubation chamber” for biochemicals of “unknown Origins” that are created out of a personally tailored, “proper” diet. That diet has sprouted brown rice, sprouted yellow corn, ground nut/sprouted grain protein drinks and so much more. As it travels through my small intestines those wonderful plant foods are digested and adsorbed to whatever degree they can be. But what is of particular interest to me is that once it exits the small intestine, the chime now goes through a process that seems to have no place in the “consciousness” of scientific research today.

        Entering my bowel, the chime hasn’t been simply digested and assimilated and is now ready for “expulsion” from the body. No indeed, it has been further “treated” with biochemicals secreted from glandular cells along the route and is now entering a “magic kingdom” of biological creation that will produce enzymes, amino acids and so much more in a way that is “perfect” for that day, that meal and that moment.

        We are what we eat is a simple statement to a life science of Infinite Proportions, Processes and Potentials…given that what is offered in any meal is by genetic law, i.e. the DNA/RNA says we are to eat this and drink that as human food…only…not just sometimes or when I feel like it or not now I’m too busy. It is obvious to me that humans are not omnivores…they only act like it because they accept sickness and disease as a “way of life” when really it is the “way of death”.

        Wow, I see why the link you referred to calls its’ lifestyle, “the Hallelujah Diet”… Amen brother! And thanks for the heads up.

        p.s. Please forgive my wordiness…I humbly say thanks for raising questions…

        • wickedchicken

          “But my colon has become an organ of incredible intelligence beyond anything I knew previously. Where it was once a “dumping ground” for dead animal carcass after carcass…ice cream cone after ice cream sundae…it has now become an “incubation chamber” for biochemicals of “unknown Origins” that are created out of a personally tailored, “proper” diet.”

          ….. nice writing style!!! Like. But really you should take a b12 supplement. Look at pubmed [every journal ever published index]. Then you will see the need!!

  • Hi Michael

    I have just posted some of your recent B12 videos on facebook to try and help my friends who refuse to accept the need to have an intake of B12 on a vegan diet.

    Most are convinced their ‘friends’ have been told by the doctors they have ‘abnormally high levels’ of B12 and have to avoid Soya milk etc. Can you advise on this? I have read there is no upper recommended limit on B12 set, and surely consuming fortified soy products wont take you to dangerous levels? I have never heard of this before.

    Can you advise if there are any known risks of excess consumption?

    • Michael Greger M.D.

      You cannot take too much B12 orally–your body will just pee out the excess. High serum “B12” levels (a lousy test) may be reflective of high levels of inactive B12 analogs (if, for example, they were eating sea vegetables). These B12 “look-alikes” are considered worse than useless and so they may in fact be at particular risk and I would urge them to start consuming B12-fortified foods or supplements with actual B12 in them.

      • B12 Curious

        I’ve heard this a lot, and it was the source of much of the cyanocobalamin naysayers. Reading the abstract, its difficult to tell what they mean by “analogues.” Can you explain the differences between these analogs and cyanocobalamin?

        • Toxins

          Analogues take up place in the receptor system (which takes 4-6 hours to recharge). Since they do not function as true b12 does, they are useless placeholders.

          • B12 Curious

            Which are the analogs to watch out for? My point is that many people believe that only methylcobalamin in true B12 and cyanocobalamin is a pseudovitamin. Nutrition facts for nutritional yeast and spirulina (two natural supplements that I’ve heard people take for B12) say 1 tsp of nut. yeast gives more than 100% of the RDA, but spirulina gives none.

          • Toxins

            I don’t think these are issues to be concerned with because Dr. Greger recommends supplementation of cyanocobalamin. I have not seen studies showing that this form is a toxin.

            Also, be weary of spirulina

      • elsie blanche

        Yes, but what about the processes in the body that have nothing to do with “excess” absorption? Is it possible that in some folks the massive dose of B12 in supplements somehow overexcites, stimulates too much, alters the immune system? I mean, our immune system reactions to things we ingest. And I’d think the immune system “senses” the gut just got hit with an amount of B12 that the human gut has never (up until supplementation) gotten hit with. Just looking for some answers as to why B12 supplements seem to really mess with some people. Totally messed up my body, and plenty of others out there as well claiming the same thing. All forms, all different kinds, additives, no additives, you name it.

  • Mana

    I just want to know that if a person is having B12 deficiency what will be more useful for him – B12 tablets or B12 shots? Or is there any other option?

    • Michael Greger M.D.

      Mana–that is such a wonderful question! For over a decade now we’ve known that tablets are a superior option.

  • Mana

    Thanks Michael!
    3 years ago I was having irregular menses. After some tests my gynecologist told that I’m having PCOD. Then I was under a medical treatment which included some hormonal tablets. Day by day I was feeling very weak. Even I did’t get the positive results, so after two years I took decision to stop the treatment and did so. Then one day I visited our family physician and told about my weakness. He asked me to do some blood tests. He told me that I’m having B12 deficiency. During my hormonal treatment my gynecologist didn’t give me multivitamin so that natural power of absorbing B12 has become very weak in my case. So he decided to give B12 shots (vitcofol 2 ml) alternate day for 1 month. Then once in a week for 1 month. Then Twice in a month for 4 months. And then once in a month. Along with this he suggested some tablets that improves immunity. Just after first three shots I receive my menses after 6 months. And surprisingly menses were regulated after that. I started feeling very very enthusiastic and fresh. Four months ago we shifted to U.S. and I didn’t take any shot from 4 months, because we don’t know anything here. Again I am feeling very weak and dull, also no menses from 4 months. I’m helpless!
    Can you please tell me is there any connection between B12 deficiency and menses? Will B12 tablets be useful for me? Can I get rid out of this?

    • wickedchicken

      Really you should get a new doc in the USA and get individual advise on your case [the internet is not a good substitute for medical diagnoses etc]. But if shots worked for you, logic would say get a doc and stick with shots. B12 is determined by several thing in PCOS [PCOD] like fasting insulin levels, insulin resistance and homocysteine levels. Maybe they should look at possible insulin resistance?? Also, in general and not specific to PCOS, some people lack intrinsic factor in their stomachs which is needed for b12 absorption [from food and pills] so shots work for them better [but it’s usually older people, over 50]. Best of luck with it.

    • DrDons

      PCOD is a condition with high male hormones and insulin resistance. It makes sense that a low fat whole plant based diet would be beneficial and studies confirm this as well. The increase in fiber decreases the hormone levels in the body by removing from the body via the stool. The diet also increases a steroid binding protein in the body thus “tying” up more of the hormones also reducing hormonal effect. The insulin resistance is decreased by the low fat diet since fats interfere with insulin and also interfere with mitochondrial functioning in the cell(mitochondria burn sugar). The B12 issue is independent of PCOD. Dr. Greger did an excellent series on B12 and the ability of the body to get B12 into the body both actively via receptors and passively see his series starting on February 3. The most pertinent video is: His video points out how you can avoid taking shots maintain your health while saving money and not having to visit the clinic.

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  • ElaineV

    Would you consider updating this post so it is more timeless? The reference to the premier of The Last Heart Attack is offputting now.

    • Michael Greger M.D.

      I changed the first sentence to de-anchor it a bit from a specific date–thanks for the suggestion Elaine!

  • Pablo Castro

    Hi Dr. Greger, what is your source for saying ovolactovegetarians should also take b12 supplements? I’m a vegan but I’m worried about all the ovolactovegetarians and lactovegetarians I know that are not taking b12 supplements.
    Thank you!

  • idan

    Great post , Just a small adjustment –  Primates are not herbivores – They are omnivores.

  • Yrsa Lindholm

    In my opinion, vitamin b12 is on of the important nutrient of the body. Mostly some neglect this, taking consideration all possible sources of this vitamin. Even I thought of using this as part of my supplementation of necessary vitamins and minerals

  • Michael Klein

    Why not take a vegan multi-vitamin (no iron) to supplement a plant based diet?   Is there a risk or problem in doing so?

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  • jules

    B12 is very very important. I can tell from experience, even though i am not vegetarian.

  • Lawrence

    Is it better to take Methylcobalamin and not Cyanocobalamin (which contains

    • I prefer methyl, but cyano is safe. I think there’s more cyanide in flaxseed.

  • I love how you wrote this article in a “matter of fact” kind of way. B12 grows in the gut of animals, lol. It’s absolutely right though. Animals don’t make it. I’ve been exploring this topic quite a bit to find some answers for myself. I’m on a whole-foods plant-based diet and don’t have any trouble finding sources of b12. Here’s my latest article on the topic.

  • Dr. Gregor:
    My wife seems to have allergic reaction to taking B12. In that when she takes a anything with B12 in it, be it soy milk, B12 supplement etc., she says she feels like vomiting the whole day.
    I have looked and cannot find anything about allergic reaction to B12. We have, the last three months, switched to a vegan diet excluding any added oils also. Now in that light, what is your suggestion about B12 supplementation for her. We do add nutritional yeast to our foods regularly. Is there enough B12 there to suffice?

    Thanks for any advice.


    • I doubt if she is allergic to the vitamin B12. It could be the company that it keeps.. either the food or additives or preservatives in the pills. I would buy a good brand of Vitamin B12 to be taken sublingually. I would make sure it only contains vitamin B12 and minimize other additives like food colorings or flavorings. If the problem persists you should consult with an allergist to help sort things out.

  • lafleuretleparfum

    Woa, already so many comments…

    Dr, I’ve got one question: how do you explain my B12 level increased since I went vegan and since I take no supplements of any kind at all??!!

    About a year ago my B12 was a bit law (139pg/mL), then I went vegan last october, now my B12 is 185pg/mL and again, I have taken no supplements of any kind!

    My idea is that 1° kicking out gluten (more than 2 years ago) helps my guts be more efficient in absorbing nutrients (the only grain I still have from time to time is brown rice).
    2° I have a big fresh home made fruits and veggetables juice almost everyday (since october), I use a lot of carrots, sometimes beetroots, organic stuff most of the time, I wash them but don’t peel them so there’s always some traces of “dirt” remaining.

    I’ll be glad to hear from you!!
    But anyway, for now I think I’ll go on being my own guinea pig, have blood tests done regularly and leave supplements aside :)

    • Serum B12 is not a sensitive test (see New Vitamin B12 Test). Doesn’t differentiate between analog (fake anti-B12) and real B12, and in fact people with severe deficiency can have elevated B12 levels in the blood. If you want to follow your B12 status I’d suggest you get a urine MMA level. You will eventually become deficient, so why not prevent it in the first place?

  • Clarisse Ginsburg

    I have posted an article about this topic

  • blope

    Hello Dr. Gregor

    Is there a significant advantage in taking methylcobalamin vs. cyanocobalamin? Or does it not make a difference?

  • Susan

    I am a Vegan and I don’t take any supplement pills whatsoever, nor do I ‘carefully plan’ my meals and in my most recent blood test, all of my levels (protein, B12, iron, calcium etc) are perfect. People need to stop worrying so much ;) Just don’t be one of those silly people that eat junky processed foods all day every day.

    • Lucille Austero

      Dangerous Susan! Read the responses Dr Greger has already made re tests for b12. To quote, “You will eventually become why not prevent it in the first place?”

    • Tommy Gun

      Hi Susan,

      Have you developed a B12 deficiency? Just interested to know as everyone on this thread is adamant that you (and other vegans) would.



  • Eskil J.

    Found that the USDA also stated back in 2000 that over 40% of people may already be having B12 deficiency or are at risk of being deficient. Also to quote:

    “Oddly, the researchers found no association between plasma B12 levels and meat, poultry, and fish intake, even though these foods supply the bulk of B12 in the diet. “It’s not because people aren’t eating enough meat,” Tucker said. “The vitamin isn’t getting absorbed.””

    So indeed this is an agricultural issue, not a dietary one. We need to get that message out there as vegans get bashed way to often for conditions even a lot of meat/dairy consumers have.

    • Thea

      Eskil: Nice post!

      I also try to remind people that everyone over 50, regardless of diet, is supposed to supplement with B12. I can’t remember where I read that, but it also helps to put the B12 issue into perspective.

      I’m going to copy your post and remember it. That’s a great contribution to this topic.

  • Sebastjan
  • Andybuildz

    Isn’t B12 with Methylcobalamin better than the supplements with cyanocobalamin ?
    ..and don’t the lozenges that go under the tongue enter the system better than the type that are swallowed?
    Thanks so much

  • shawncaroline

    Dr. Greger – I was diagnosed with a B12 deficiency about 2 weeks before my official diagnosis of MS. Neurologists have told me over and over that the B12 deficiency is not related to the MS, but since B12 protects the nervous system, which my immune system is currently destroying, doesn’t it make sense that I would be B12 deficient? Before my my MS diagnosis, I ate meat and dairy multiple times a day. So why would I have been B12 deficient? Now I NEVER eat milk products, rarely eat meat, but continue to eat fish and mostly whole, plant-based foods. After they discovered my B12 was low, I had to do B12 shots for 2 months. Now I take 1000 mcg every single day. Do you think this is too much? I would love to hear your opinion and do worry that supplements increase cancer risk and other random health issues. B12 absorption is apparently pretty complicated, so I do worry about B12 quite a bit. When I have my yearly physical, I always ask them for a B12 level test and I have been good for 2 years now. Thank you, Shawn

  • Wedad Ajus

    What about the need of B12 in infants and babies’ diet ? what should we feed them ?

  • tina stamatakis

    hi dr. greger. am i the only one that finds this all very confusing? i don’t mean vitamin B12 consumption exclusively but nutrition in general…
    specifically my question today is about cyanocobalamin and smoking. i am a smoker (i know, i know) and am considering taking a B12 supplement. should i look for one containing methylcobalamin? have i understood the information correctly. thanks for your help.

  • This b12 debate is very interesting, especially as there are no absolute conclusions and at best educated guesses or amazing confusion as to where the b12 comes from in various sources of food found to contain the vitamin. This article from vegan is another comprehensive yet non concluding take on the issue, and it’s conclusion is a better safe than sorry type of situation. There seem to be quite a few stances on this anywhere from we produce it through our intestinal bacteria given we have a pro biotic culture inside to we must take it from supplements. I personally get this question often and have yet to find a good enough answer to provide as the debate continues. I would say, unless you have clear symptoms of deficiency, not self diagnosed, first look to how long you’ve been vegan?, how was your health before you transitioned?, have you detoxed your body?, do you have a healthy gut flora, and before adding a bunch of supplements make sure you’ve taken steps to reverse the system from old habits.

    • Thea

      Lasse: Nice post.

      On this topic, I consdier the experiment talked about in the following video to be pretty compelling:

      In other words, I think the experiment did a good job of showing, “Why don’t the bacteria in our colon make B12? They do actually. It’s just too far downstream to be absorbed.”

      This probably does not address all of your issues, but I thought you would want to see the video if you haven’t already.

      • Thea, Thank you for that video. It seems in the end with all the debate around diet, it really isn’t the issue. The real issue is environment, our food is too clean, no bacteria enters our bodies to produce b12, I guess maybe i’m not deficient perhaps because i don’t wash my vegetables and eat the skin on most as well. So supplements are the best way after all, whether vegan or omnivore, and yet again we get to the argument, why then be an omnivore, it seems like it comes at a high cost, excess fat, cholesterol and hormones, not to mention excess of unnatural elements like antibiotics etc.

        • Thea

          Lasse Larsen: Exactly! I couldn’t agree with you more.

        • Leslie

          Herbivores/plant-eaters in out in nature eat lots of bugs, worms, insects, that are on the veggies they consume. These bugs have lots of B12.

  • Almost Vegan

    How much B12 should a one year old get? Does the “you can’t overdose on B12” also apply to babies?

  • Charlotte Parker

    Has anyone heard of Eligen B12? It’s a prescription oral tablet I recently read about that works as well as the IM B12 injection, even if you don’t have intrinsic factor. Apparently it came out a month or two ago

  • luaV_19

    Dr, i was taking a daily 2,000 mcg dose of sublingual b12 to increase my b12 levels, and i tought it was safe cause i read everywhere that it is…but….one month later my skin is terrible and full of acne (even in my chest!). Can you tell me why is that? and what can i do about it? if i take 2000 mcg weekly not daily it will solve the problem?. (by the way, i never had acne, not even when i used to have a pretty bad nutrition).Thank you

  • Tommy Gun

    Michael Greger M.D. I watched your talk ‘Documentary On Leading Causes Of Death – Delay Death With Veganism’ (Very very good by the way) and you mentioned nothing about vegans being deficient in B12 or supplementing it. Are you still recommending vegans to supplement B12?



    • Thea

      Tommy: Yes, Dr. Greger (and all the plant based docs I know of) still recommends B12 supplements. Dr. Greger repeated this recommendation in his brand new book, How Not To Die.

      (My own 2 cents is that since so many humans who eat animals also suffer from B12 deficiency, it would be a good idea for most people to take the B12 supplement regardless of diet.)

      • Tommy Gun

        Well I’ve been a vegetarian for over a year and half and a vegan nearly 6 months and I feel better than ever and have no symptoms of any vitamin deficiency. However I know the onset or symptoms of B12 deficiency sometimes don’t show up for 2 or 3 years. Saying that there are so many factors to consider in one’s life that effect diet. Furthermore there’s the intrinsic factor to take into account and too much/little acid effects B12 absorption too.

        How does any one know B12 supplements are not toxic to the body?

        Where’s the evidence that B12 supplements are absorbed by the body and work? and why cannot diet alone be sufficient alone?

        These studies paint a different picture about B12;

        Vitamin B12 Sources and Bioavailability

        The usual dietary sources of vitamin B12 are animal foods, meat, milk, egg, fish, and shellfish. As the intrinsic factor-mediated intestinal absorption system is estimated to be saturated at about 1.5–2.0 μg per meal under physiologic conditions, vitamin B12 bioavailability significantly decreases with increasing intake of vitamin B12 per meal. The bioavailability of vitamin B12 in healthy humans from fish meat, sheep meat, and chicken meat averaged 42%, 56%–89%, and 61%–66%, respectively. Vitamin B12 in eggs seems to be poorly absorbed (< 9%) relative to other animal food products. In the Dietary Reference Intakes in the United States and Japan, it is assumed that 50% of dietary vitamin B12 is absorbed by healthy adults with normal gastro-intestinal function. Some plant foods, dried green and purple lavers (nori) contain substantial amounts of vitamin B12, although other edible algae contained none or only traces of vitamin B12. Most of the edible blue-green algae (cyanobacteria) used for human supplements predominately contain pseudovitamin B12, which is inactive in humans. The edible cyanobacteria are not suitable for use as vitamin B12 sources, especially in vegans. Fortified breakfast cereals are a particularly valuable source of vitamin B12 for vegans and elderly people. Production of some vitamin B12-enriched vegetables is also being devised.


        Vitamin B12-Containing Plant Food Sources for Vegetarians

        The usual dietary sources of Vitamin B12 are animal-derived foods, although a few plant-based foods contain substantial amounts of Vitamin B12. To prevent Vitamin B12 deficiency in high-risk populations such as vegetarians, it is necessary to identify plant-derived foods that contain high levels of Vitamin B12. A survey of naturally occurring plant-derived food sources with high Vitamin B12 contents suggested that dried purple laver (nori) is the most suitable Vitamin B12 source presently available for vegetarians. Furthermore, dried purple laver also contains high levels of other nutrients that are lacking in vegetarian diets, such as iron and n-3 polyunsaturated fatty acids. Dried purple laver is a natural plant product and it is suitable for most people in various vegetarian groups.

        I'm not entirely convinced about the whole B12 paradigm! May be people need to actually live an active life with a balanced fresh organic plant based diet, yoga, balance etc. As you say there's people that are deficient in B12 across all diets and this suggest to me they do not eat a balanced diet, eat processed foods etc. What about other vitamin deficiency being the precursor to B12 deficiency etc.


        I'm no doctor but I know what my body needs because it tell me and I research deeply into the subject matter surrounding diet, health etc., but I could still get B12 deficiency, but I doubt it.


  • sharon

    We have been vegans for about a year and a half and have taken our B12 with methylcolbamine supplements. We currently take 5,000 mcg a week. I just get that dose because it is what Costo has at a great price. My concern is that my 17 year old daughter said she has been having some issues with remembering things… memory loss. Should she be taking an additional B vitamin supplement. I tried Googling this but there are SO many different answers to these questions online and it is confusing. Should I maybe take her in to the doctor to get her B12 level checked?