Best Way to Get B-12

Image Credit: dominiquegodbout / Flickr

What is the best way to get vitamin B12?

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?

Vas Bouras / Originally asked in Vegan B12 Deficiency: Putting it Into Perspective


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). I have a video about it here: Cheapest Source of Vitamin B12.

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–see my video Daily Source of Vitamin B12). I also cover B12-fortified foods in that video. Such foods can be as exotic as a certain type of “nutritional yeast” or as simple as a bowl of Cheerios.

As I showed in Vegan Epidemic, ovo-lacto vegetarians are also at risk for deficiency. For why fortified foods and supplements are the best sources of B12 see my video Safest Source of B12. Eggs and dairy are not optimal sources of vitamin B12 because foods come as a package deal and eggs and dairy may bring along as baggage saturated fatcholesterol, and hormones). For more see my blog Vitamin B12: how much, how often?

Image credit: dominiquegodbout / 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.

91 responses to “What is the best way to get vitamin B12?

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  1. Hi Dr. Greger,

    Great site! I was wondering if you could combine Azomite (an edible clay high in the cobalt necessary to produce B12) with some non dairy Kefir (high in natural bacteria) to produce Vit B12 in the gut? I saw this suggestion in an online forum and would like to know if this would work? Thanks.

    1. I would stick with Dr. Greger’s recommendations for Vitamin B12 see… and avoid Azomite which contains trace minerals. With the increasing evidence that Alzheimer’s disease is associated with Aluminum, Zinc, Copper and Iron (another reason to not take multivitamins) it is best to limit supplements to Vit B12, iodized salt and food to get what we need. Also some non dairy kefir is made from coconut milk which should be avoided see… Dr. Neal Barnard’s recent book, Power Foods for the Brain, is a good resource for folks wanting to learn more about avoiding dementia.

      1. Thank you, Dr. Forrester! I became a vegan after reading Dr. Barnard’s book Food for Life. The B12 requirement has always been a conundrum for me, as I don’t like taking supplements or eating commercial cereals (I buy my oatmeal in bulk). At least now I know to stay away from Azomite clay! I guess I’ll just take a B12 supplement once a month. Hopefully, that’ll do the trick. You guys are great. Saludos!

      2. Hello Dr. Forrester, the question has already been asked but could you tell me if cyanocobalamin comes from animals? Thank you.

      3. Dr Forrester what kind of supplements are you talking about here? I have have many good results of people who suffered many conditions and they all get well on alkaline water and supplements,, i would like to know what kind of supplements…i have recommended ph mIRACLE SUPPLEMENTS which are food…of course full of trace minerals and antioxidants …good results even in people with Alzheimers disease

  2. I’ve been diagnosed homozygous mthfr c677t. I’m taking methyl folate and chomping methyl b 12 and eating vegan, avoiding foods fortified with the form of b12 and folic acid my body can’t use, also avoiding sulphur foods like leafy greens, onion and garlic, since i apparently have problems with SUOX and CBS. Do you have any recommendations for a diet that would encourage b12 absobtion?

    1. I’m not familiar with your diagnosis but Dr. Greger’s 5 video series running from 2/3 to 2/9/12 should give you the information that you need to insure adequate B12 intake. Of course you can test to see if you have adequate levels and this is discussed in the last video of the series. Good luck.

    2. Why avoid the sulfur foods with this condition? Which leafy greens, if any, do you eat? Thanks for any info.
      Also, which tests did you run to discover this?

    1. I’ve been told this, too. In Cornell’s Plant Based Nutrition certification program, Dr. Campbell said that methyl B12 is the better source.

    2. Thank you for bringing this up!

      Methylcobalamin vs cyanocobalamin

      Cyanocobalamin exists only as a cheap chemical synthesized in laboratories. It doesn’t occur naturally in any living organism and also has a cyanide group, and it is an inactive form of Vitamin B12 that requires a number of metabolic processes to gain any benefit

      Cyanocobalamin isn’t something nature ever intended your body to deal with. Your body has no use for the cyano- compound itself, and has to convert any cyanocobalamin you take into methylcobalamin.

      A small amount of cyanide is released during the conversion process that must then be removed from your body by your liver.

      By taking synthetic cyanobalamin, you’re actually stealing methyl groups from your body, using up substances such as glutathione and making it do more work at the biochemical level.

      Cyanocobalamin, in summary, is a low-grade, low-quality and slightly toxic (cyanide) form of vitamin B-12 that’s used by all the cheap vitamin manufacturers. You get what you pay for.

      Methylcobalamin is a biologically active form of B12 that exists in nature. Because is pre-methylated, your biochemistry can use it immediately without any metabolic steps to make it body friendly.

      Methylcobalamin research has shown that it remains in the body for a longer period of time, with increased absorption, better retention in tissues, and at higher levels than cyanocobalamin, and of course, no cyanide!

      Pills are an inferior method of taking B12 as studies have shown that up to 99% is wasted.
      The best methods to take B-12 is injections, sublingual absorption and skin absorption.
      Because injection must be done by trained professionals, sublingual absorption and skin absorption is the most practical for most people.

      But beware that many sublingual formulas are cyanocobalamin. This is changing but you must check the label to ensure that you are getting the vastly superior methylcobalamin.

      Skin patches are available that deliver methylcobalamin released over a 1-2 day period. Again, be sure that it is methylcobalamin if you care about this difference.

      The sublingual spray form that I just discovered a few months ago is extracted from Saccharomyces cerevisiae according to the label, and is a species of yeast according to my research. (Mykind-Garden of Life). I’m sure there are others.
      I am biased as any supplements I use must be made with and from organic foods and natural sources, as well as my food as well must be organic. This is just my personal requirements and to each his own.

      1. What about adenosylcobalamin? I heard that’s also easily absorbed and used by the body as well. One thing I was wondering about though concerning sublingual methylcobalamin supplements is whether they might cause problems for people with mercury fillings in their mouths.

        Some stuff I read on internet forums seems to suggest this may be the case, but I have no idea. Methylcobalamin seems like it’s kindof a new thing in the supplement world isn’t it? Cyanocobalamin supplements seem like they’re what people have been using for a long time. I wonder if it’s been studied if methylcobalamin causes a problem with mercury fillings, or if it hasn’t been investigated yet because methylcobalamin is a new development in supplements.

      1. I too just heard Dr. Greger say that well water was a source (in a video where he is guest). I’m on a well now and wonder how to test this possibility. In the future I’ll be on a rain-water system, so I’m glad to know ahead of time that I may be losing a viable b12 source and need to take steps to replace it.

        1. I highly respect Dr Greger, but i would not trust getting my b12 from well water. The b12 supplements are cheap and easy to take and trust worthy !!!!

          1. I am not sure Dr. Greger ever said get B-12 from well water. He may have said it “may” be a source, (especially long ago when bacteria in water was not controlled) but there is no way that can be a reliable source! Same for dirt on plants, seaweed, and other mock-B12 sources. You’re thinking right though, take a B-12 supplement!

            For more info: Adults needs roughly 2.4 micrograms per day. In supplement form it comes in higher doses. Cheapest source of B12.

            For detailed Optimal Nutrition Recommendations:

            Thanks, bigal

            1. I want to test my well water. No one knows what it can be relied upon without that part. I did not mean to imply that Dr. Greger suggested relying on any source. He just glosses right over the fact that millions of rural dwellers get their water from non-chlorinated sources. I’m not interested in supplements or fortified foods. I get plenty of “flex” food.

          2. I would test the water before I would rely upon it, and really-reliance is not an issue as I’m “flexitarian”. But it still could be a viable source for strict eaters.

  3. Dear Dr. Greger/Dr.Toxins :), I have an important practical question. In a place I live the only available form of B12 are 500 mcg shots (dirt cheap). What would you advise to do with them – have those shots intramuscularly (which, I get, provide way more b12 per dosage, yet I’m concerned if, say, weekly – or could those be monthly? – shots is too much for my muscle) or should I just drink – (or take sublingually?) -the contents of five shots every week? (If monthly shots of say 1000 mcg is all I need I’d probably go for that way. I remember reading somewhere, China Study maybe?, some rurally guys in Asia had a custom of monthly b12 shot – seems like an easy way to me). Also I suspect I might be quite b12 deficient based on history of my diet (no test available to me to validate). Would you advise a short course of shots to make sure the deficiency is no more there and, if so, what protocol would seem safe and sufficient?

  4. I’d also like to share an idea – unusual one – no problem if you delete this. If you are into myofascial/trigger points topic you probably know in most people calves muscles are usually quite stuffed with trigger points which cause constant pain when walking – easily harming the optimal biomechanics of both everyday and athletic movement – while some specialists even suggest tightness in calves (permanent spasm in some parts of a muscle) might cause restricted blood flow which may increase a load on heart to provide an adequate peripheral circulation, casing extra fatigue overall. So, getting to b12 now, – I found that having shots in my calves (aiming for located tender points – read Travell/Simmons book or just browse some web for more info on trigger points therapy aka dry needling) can release those trigger points quite successfully (some learning curve required to locate exact shot points to get a desired twitch/release result). After a series of shots (yet lacking any timeline so far – see my other post with a question) my calves are WAY loser – which makes a world of difference when moving around. Looks like two birds with one stone to me :)

  5. can you compare cyanocobalamin and methylcobalamin (or is it methcobalamin) and are the two interchangeable. Also info on dosing b/t the two, please. thanks

  6. Cyanocobalamin is not a natural substance.

    Better use cyanocobalamin methylcobalamin or hydroxocobalamin those are the naturally occuring ones. Unless you need your everyday dose of cyanide that comes with the cyanocobalamin ;)

  7. Dear Dr. Greger;

    I know that people need to absorb about 4 to 7 mcg of B12 per day, but because the absorption rate from B12 supplements is so low, we need either 250 mcg a day or 2500 mcg per week.

    This makes me concerned with the absorption of B12 in fortified foods.

    The soy milk I drink says it has 50% of daily B12 per cup, and the veggie-sausage in my fridge says each of them have 120% of daily B12.

    How efficient is the absorption of B12 from fortified foods? I know it’s better than from supplements, but how much better?

    Will two glasses of soy milk REALLY give me 100% of the B12 I need for the day? Or is it more like 70%? 20%? 5%? I have no idea!

    Please help! Thank you! :)

    1. You can get adequate B12 from fortified foods if you do it correctly. You don’t need to worry too much about meeting daily requirements as you store B12. I would view the series of 5 videos that Dr. Greger posted in February 2012 to understand this important issue in more depth. Personally I take a 2500 mcg sublingual tablet weekly to make sure I have adequate intake but since I also consume some fortified foods like almond milk I don’t worry about the occasional weeks I forget to take the tablet. Since most of us periodically get blood work done it is easy enough to ask your physician to check your B12 level. Of course if you are having symptoms of illness you need to be checked. Good luck.

      1. Hello. Please guide me on the following. Dr Gregor recommends cyanocobalamin and others recommend methylcobalamin. Is Gregor’s recommendation valid?

        1. Hello Selene, and thank you for your question,

          I am a family doctor and also a volunteer for Dr. Greger on this website. Dr. Greger recommends cyanocobalamin because it is the cheapest form, and is extremely well tolerated by over 99% of people. Here is what Dr. G had to say about cyanocobalamin:

          Methylcobalamin is the active form of vitamin B12, but almost everyone has the appropriate enzyme to “methylate” the cyanocobalamin into the active form. (There is a rare gene mutation which results in decreased ability to methylate certain pro-enzymes into their active forms, but I seriously doubt that you have that.

          So, there’s nothing wrong with taking methylcobalamin, it’s just that it’s almost certainly a waste of money.

          I hope this helps.
          Dr. Jon

          Health Support Volunteer for

  8. Do I understand it correctly? The drug companies in my country sell pills/drops with 25µg cyanocobalamin a day and say it’s 1000% of demand. How can I get 250µg
    a day(it’d be 10 pills)? Please, can you explain it to me?

    1. the website iherb sells B12 liquid drops or B12 liquid spray and it’s often 250, 500, 1000, or 2500 in each drop or spray. iherb sells supplements at a discount, no sales tax if you spend more than $20, and if you’re in the usa no shipping.

  9. There is a lot of confusion about the proper method for testing B12 levels in the blood. Some say the traditional method is sufficient, others claim that the latter s not accurate and that measuring Methylmalonic acid and/or Homocysteine levels is the way to go. What gives ?

  10. Which form of supplementation is better, pills or fortified foods? A pill contain many additional ingredients that might not be of any good to our bodies, what about fortified foods, what kind of stuff is there in those, is it safer than pills?

  11. Dr I’m very concer about my allergys can you suggest me some changes in my life styles I was vegetarian all my life and 10 months ago I changed to vegan practicing 70/30, but I can’t eat strawberries mine favorite fruit or any nuts including sprouted, I feel I have no life/fun my face get red pimples and looks like I’m a pre teens and I have 55+ old what can I do, please help. Thank you. Ada

  12. Based on Dr. Greger’s recommendation, I have stopped taking spirulana, but I noticed that the DHA I take lists Algal Oil as the main ingredient, and I’m wondering if that is the same as spirulana and/or is just as potentially dangerous. Thanks for your help.

    1. Sara: I’m not an expert in this area, but I have a thought for you.

      I think the algae that the oil comes from is not spirulana. But even if the factories are growing spirulana to make the oil, they are growing that stuff in sterile, fully controlled environments. They are not gathering the algae from wild/open places. Since the spirulana only seems to be a problem when it is *contaminated,* (ie, the spirulana itself is no the problem), then the stuff grown in vats in a factory should not be a problem.

      Also, I would bet that Dr. Greger keeps an eye out for this kind of information. If there were any evidence at all, even a case study, that someone got sick from the DHA algae pills, I would expect that Dr. Greger would do a video about it and have warned us. He has done so for other substances…

      Hope that helps.

  13. Michael, in your opinion, is taking spirulina counter-productive when also taking a vitamin B12 supplement? As a relatively new vegan I have been researching supplements and some sources indicate that the B12 in spirulina is in an analogue form which blocks absorption of true B12.

  14. >> eggs and dairy may bring along as baggage saturated fat, cholesterol, and hormones >>

    Do you make much distinction between “factory eggs” and free range eggs, in terms of hormones and overall benefits?

    Before discovering this site, I’d learned that free range eggs have up to FOUR times the omega 3 fatty acids. In addition, according to “Mother Earth News” (see link below; no idea how solid it is as a source, but I’ve seen simliar info elsewhere), free ranges eggs have:
    * 1/3 less cholesterol
    * 1/4 less saturated fat
    * 2/3 more vitamin A
    * Three times more vitamin E, and
    * Seven times more beta carotene

    Read more:

    So – is much of the rap on eggs mostly against “factory eggs” or do you attribute all the negative stuff I’ve read here to regular, old-fashioned free range eggs as well?

    I love my plant-based diet, but kind of miss eggs once in a while.

    1. bluesky: 1/3 less cholesterol, etc – that’s still a WHOLE LOT of cholesterol, saturated fat, etc. Plus other problems with eggs that exist regardless of how the mother of the egg was raised…

      I understand missing eggs every once in a while. I really, really do. I don’t know if you already know about “black salt”, but you may want to research it. It does a great job of making some dishes really taste egg-y. (It is a natural salt that has sulfur in it.) It’s not 100% the same. But it can help to fill that hole.

      Good luck.

    2. Sandy, I know your question is five months old, but I just came upon this article yesterday and thought you might find it very helpful: Incredible Vegan Versions of Every Egg Dish. (The article also has links to more info about what eggs really are and why “backyard chickens” are not an ethical answer, plus it contains more info about kala namak, the “black salt” Thea mentioned that imparts an eggy aroma and flavor to dishes).

      1. Laloofah: Just wanted to let you know that I really appreciated your link. That link was cool just by itself, but then it led me to learn about the Gentle Chef and oh boy have I had some fun getting one of his cookbooks and exploring his blog recipes. Very cool. Thank you!

  15. I’ve been vegan for 7 years and never felt better – not even a cold during that time. However I have been on B12 supplements since my mid 20’s due to a lack of intrinsic factor, which pulls B12 into the body from the gastrointestinal tract. I had monthly injections for many years, then discovered that taking a large supplement orally daily/weekly would do as well, since some B12 enters the body directly without the need for intrinsic factor. Of course a lot of the ingested vitamin is wasted – but it’s not an expensive vitamin. I get my bottles of B12 from Costco – the vitamin comany uses a vegan.vegetarian source for their B12 so I am not harming animals.

    1. No, Methylcobalamin is the natural biologically active form of B12 that exists in
      nature. Because is pre-methylated, your biochemistry can use it
      immediately without any metabolic steps to make it body friendly.

      Cyanocobalamin is chemical synthesized in laboratories. It doesn’t occur naturally in any living organism and also has a cyanide group.

      Your body has no use for the cyano- compound itself, and has to
      convert any cyanocobalamin you take into methylcobalamin. This also releases a small amount of cyanide in the process.

    1. Dani: Dr. Greger answers this question here:

      In his new book, How Not To Die, Dr. Greger provides a slightly different reason for the same answer: that cyanocobalamin is preferred, because other types, like methylcobalamin have insufficient evidence to support their efficacy. In other words, we know *cyanocobalamin* works. You are paying more for methylcobalamin and we don’t even know if it works as well.

      Between these two answers, what do you think? If your source still compelling to you?

  16. I’m a little surprised by the advise to take weekly high doses of B12. This seems more disruptive than a gentle flow of B12 entering our blood streams; and indeed, B12-fortified foods are mentioned as the most reliable method of getting enough B12.

    What I am considering is to take a 100 mcg tablet, dissolve it in a liquid and drink that throughout the day. Or perhaps prepare a number of liquids that can be used up in their own pace, over a number of days. In effect, this would be making our own B12-fortified liquids. As I understand it B12 is water-soluble, very stable, and can even withstand high temperatures, so there should be many opportunities.

    Given our body’s wish for 1.5 mcg doses 3-4 times a day, one such 100 mcg tablet could easily serve an entire family for a full day. All we would need to care about is entering just a little into the 1% overshoot beyond 1.5 mcg, at least most of the time. Is there a reason why this approach isn’t advised here?

    1. Lisa: As near as I can tell, the page you linked to does not give a single reference to back up anything it says. Here’s what Dr. Greger said on the topic when he did his Reddit day:

      “As far as I’m aware, nearly all documented B12 deficiency reversal in those on plant based diets has been done on cyanocobalamin. In fact the only study I know of with methyl was one in which one out of the three treated didn’t completely resolve! So better safe than sorry I say, until we have more data.”

      from Reddit day, December 10, 2015

      That’s a pretty strong argument in my opinion.

  17. Hi Dr Gregor, I read in Tim Spector’s Diet Myth (recommend it, research based and a good read; based mostly on twin studies) that he had no luck with B12 supplements and resorted to eating one steak a month and that did the trick. What are your thoughts on that?

  18. If a vegan diet is what our bodies have evolved to respond to best, why do we need factory made B12 supplements to remain healthy? How did our ancient vegan ancestors (or even more recent vegan ancestors) flourish without access to B12 supplements? Are there other vegan ways to ingest sufficient B12? If so why isn’t that recommended? If not, how can we claim a vegan diet is healthiest if it requires chemical supplementation?


    1. Jeff: This question comes up all the time. The thing to understand is that B12 is made from bacteria that lives very far down your digestive track. What’s more, the B12 is made so far down your digestive track that your body does not absorb (enough of) the B12. So, we have to get our B12 from our diet.
      How do we know all this? NutritionFacts has a video, , which talks about an experiment where people who were deficient in B12 were given pills made out of their own poop. It solved the B12 deficiency problem.
      Because B12 is made from bacteria that lives in the lower part of animal’s digestive tracks, there are all sorts of ways to get B12, for example: poop encrusted chicken (look up how chicken is processed in America), dirty water, and unwashed plants. Having a B12 deficiency problem is more likely a problem of living in a sterile world than an issue of “it’s only natural for humans to eat meat.”
      Also consider that everyone over a certain age (I can’t remember the age) is supposed to take a B12 supplement regardless of their diet, because B12 absorption goes way down as we get older. Does this mean that humans are not naturally supposed to live past 60? Here’s my point: Understanding what’s “natural” for humans is not a straight forward subject. What’s more, the concept of “natural” is often not a helpful angle to take when deciding what is the healthiest step for you to take today. It’s natural to drink dirty water filled with cholera. Just because that activity is “natural” doesn’t mean that it is the best course to take.
      To drive home the point: consider that food is a package deal. As explained in the video I linked to above, “Just like we can’t get the iron in beef without the saturated fat, the protein in pork without lard, the calcium in dairy without hormones; we can’t get the B12 in animals without also consuming stuff we don’t want—like cholesterol.” You get the bad with the good when you eat animals or drink dirty water. On the other hand, a simple and cheap supplement gives you all the benefits with none of the risks. Given the world we live in, that’s the choice that seems the most natural and wise to me.
      Following is a good NutritionFacts article that puts B12 into perspective:
      I hope this helps.

  19. I was asked by my ND to take a MTHER test . I decided not to and opted for the methylcoblamin instead of the coblamin.
    My blood range was slightly high at the time. I believe it was 101 and I use the spray daily. When I got my next blood test done
    after 6 months my levels were at 95.

    Prior to that blood test I had not used the daily spray for 4 days. I wanted to make sure I could say I retained it in my blood
    on it’s own without supplementation present. I take Pure Advantage B-12 which is vegan certified after reading many reviews
    that were posted on Amazon.

    I do not know which one is better. I decided to try one before the other. It appeared to work for me but I also think as you age
    many things change so a watchful proactive mind is the best approach with anything you do.

    As for meat I am not a plant eater. I am going to try it because I love plant material more than meat so the change will be fairly
    easy for me. I also do not eat food for entertainment.

    I have learned protect your body, trust in yourself, do your homework, and learn about your own body or what the body is made up of and needs and why. Education is key. The more you learn the more comfortable you get with difficult choices you may have to make for yourself. I have some very old books copied in the late 1800’s and they all talk about more education to prevent disease. They speak of gluten, casein, juicing veggies, among other things. I can see warnings were put forth years ago.

    I think both sides of medicine are good in their own ways but in the middle is you and I and we play a strong role. We can’t
    post blame on one side to the other if we choose not to know and understand the human body and what our responsibilities are.

  20. The RDI for B12 is 2.5ug. I assume that Dr. Greger and most supplements recommend much higher doses. Is this because it isn’t absorbed easily? When I first decided to try vegan, I took a supplement which I thought read 15ug but in fact it read 15mg which works out to 15000ug. I did this for 3 months. My bloodwork showed elevated levels of B12. Would over supplementing do this? I thought the extra gets excreted into the urine. I now switched to 5000ug once per week. I recently found a daily supplement that is called VEG 1. It has 20ug vitamin D, 16ug B2, 2mg B6, 200ug folic acid, 25ug B12, 60ug Selenium, 150ug Iodine. Can this combo cause GI upset?

  21. Hi Pat, I’m a volunteer for Dr. Greger. You have some great questions there.

    First, Dr. Greger recommends either taking 2,500ug/week or 250ug/day. Our body has 2 ways of absorbing vitamin b12, which Dr. Greger explains in this video:

    I wouldn’t suspect your B12 levels being high as being an issue, especially if your doctor made no mention of it when you got your blood levels back.

    The daily supplement seems a bit unnecessary. With the exception of vitamin B12, vitamin D (if you don’t get enough sunlight and live in a high latitude area), and possibly iodine (although most people don’t have to worry about this), if you’re eating a balanced diet, you shouldn’t need to worry about any other nutrient. It’s possible that it could cause GI issues, but probably not likely.

    Hopefully this helped to answer all your questions!

  22. I just finished reading “How Not to Die” and loved it! Our family is a few months into eating a vegetarian diet, and I need some help finding an appropriate dose of B12 for my kids. They don’t like almond or coconut milks, and we have a soy allergy to consider, so B12 fortified soy milk is out, too. Our pediatrician recommend a children’s Multivitamin, but none of the ones I have looked at contain B12, and being on a plant-based, it’s really only the B12 that concerns me.
    Would giving them half of a 2500 mcg tablet once a week be sufficient? Would it be too much? They are ages 12, 10, and 6.
    Any help would be greatly appreciated!

  23. Hello Amanda,
    Thank you for your question. Dr. Greger has done lots of videos on Vitamin B-12.

    Here are his most recent overall recommendations about supplements:

    Here is an article he wrote on “Vitamin B-12: How much, how often”:

    He doesn’t give recommendations for children. Luckily B-12 is water-soluble and it is nearly impossible to overdose —

    Finally, here is a video that discusses B-12 deficiency syndromes:

    What I recommend is that vegan children should take 250 mcg per day; cyanocobalamin is the cheapest form, and Dr. Greger says getting any of the more expensive alternatives is just a waste of money.

    I hope this helps.
    Dr. Jon

    1. Could you also explain what this maximum of 55mcg/d means when taking vitamin B12 only once or twice a week?
      Is it related to the absorbed amount of (1.5 + x/100) you mentioned in another video, or is it just the total amount consumed that matters? If the latter, should we rather take small doses (<10mcg) twice or three times a day?

  24. Hi Jan St.

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

    Vitamin B12 is absorbed by the body in 2 different ways. The first way, the body absorbs a moderate percentage (20-60%) of a smaller dosage of vitamin B-12 taken every day. The second way, the small intestines absorb a very small amount (about 1%) of a large dose. So you can either take 250 micrograms every single day, or you can take 2,500 micrograms once/week, which the body will absorb about 1% of (coming to about 2.5 micrograms), which is enough to meet the requirements.

    I hope this helps to answer your question!

    1. Hey,

      I think you should supplement, but how much? You should consult this question with your pediatrician.

      Take care,

      Moderator Adam P.

    1. Vecvolta,

      this is rare but possible. Are you sure you are allergic to the vitamin itself? And not the supplement? It could be the additives in pill.Try to buy a trusted brand of Vitamin B12 (sublingual form). Try to make sure it only contains vitamin B12 and minimize other additives. If the problem persists you should consult with allergist/immunologist.

      Hope this helps,

      Moderator Adam P.

      1. vitamin B 12
        you mention the cyanocobalamin form of vitamin B 12. i have read that the methylcobalamin form is superior to the cyanocobalamin form because the body has to convert the cyanocobalamin form into methhylcobalamin in order to function properly. this makes it more readily bioavailable; meaning it is more easily absorbed into the system.

        please clarify this for me.


  25. Hello Michael Cluney

    I’m a volunteer for Dr. Greger. If you interest in knowing more about Vitamin B12, you should check all the videos here at related to the topic, including the ones Dr. Greger cited in his article.

    As for your concern, vitamin B12 supplements are generally recommended in the form of cyanocobalamin, they are consider safe, and as is cited here “Some non-authoritative websites claim that methylcobalamin is better absorbed or more bioavailable than cyanocobalamin, but there is no clinical evidence supporting this claim. Other sites suggest that methylcobalamin supplements cannot yield one of the important, active metabolites of B-12, but this is not correct”

    If you want more info about Vit. B12 supplements maybe you can check these researches:

    Vitamin B12 Deficiency: Recognition and Management.

    Vitamin B Supplementation: What’s the Right Choice for Your Patients?

    Remember that you can also have your vitamin B12 from fortified foods :)

    Hope this was from help

  26. I am an 80 year old male and have been following Dr. Greger’s vegan diet for a little over a year. The diet is wonderful and I feel years younger.
    I especially enjoy the absence of aches and pains . The anti-inflammation foods work.
    About 4 weeks ago, I took a blood test for Vitamin B12.The results showed that I was in the safe range but in the lower end of the scale.
    I have been eating one serving of fish each week to get vitamin B12.
    My doctor recommended taking supplements to boost my B12. For 31/2 weeks, I have been taking 500 mcg of meth B12.daily. I take no other pills.
    About 1 week ago I started getting aches and pains. One day my foot would hurt. the next day my shoulder. My knees started to hurt. My walking was wobbly. Two days ago my thumb felt like I had closed the car door on it. Today , my big toe hurts.
    Below is a list of B12 supplement side effects that I found on the web. All my aches and pains are on the list.
    I think that Dr. Greger should have warned us of the possible negative side effects caused by B12 supplements.
    I am taking no more . I will double up on servings of fish.

    1. Arthur,

      I’m thrilled to hear of your success with the WFPB diet.

      It’s really rare that someone would have a negative reaction to a B12 oral supplement.

      With that said……. you may indeed be experiencing a reaction. I would question if your reaction is to the B12 or one of the excipients in the tablets. Regardless, your on mark to discontinue and see what works for your body.

      Have you considered that the test you took is highly inaccurate in terms of actual B12 tissue levels? The correct testing for B12, is using the MMA test, see: “” and .

      Find what works well for you and keep feeling younger ! Consider having your vitamin D levels checked at your next lab evaluation.

      Dr. Alan Kadish moderator for Dr. Greger

      1. Hi Dr,

        I have been recommended to increase my folate B12 intake (currently 500) as my platelet count is low (currently 116). But will increasing my B12 also increase my iron levels? If so, are there any dietary recommendations I can follow (eg. I read that drinking black tea can inhibit iron intake)?

        The reason I ask is that I have one gene of haemochromatosis . In last few months on WFPB my T. Sat has risen from 38 to 51% yet my Ferritin has fallen from 64 to 56. I was told this signals an iron overload issue and am eager to not have it rise further.

        Thanks for your help.

  27. Vitamin B12 supplements are dangerous.






    Can Vitamin B-12 Cause Side Effects?

    Side effects
    See a doctor
    Bottom line

    How your body uses B-12

    Everyone needs vitamin B-12, and most people get enough through their diet. However, it’s important to know what side effects occur when you take too much.

    Vitamin B-12 is water soluble and absorbed in the intestines. After it is absorbed, it is used to make DNA and red blood cells. Vitamin B-12 that is not being used is stored in the liver. But if you take supplements, you might ingest more than your body needs.

    What are the side effects of vitamin B-12?

    Vitamin B-12 is safe to take at recommended doses for healthy people.

    Vitamin B-12 can cause the following side effects:
    restenosis (reoccurrence of narrowing of a blood vessel) after stent placement
    high blood pressure immediately after injecting vitamin B-12
    cold symptoms, such as coughing or runny nose (nasopharyngitis)
    itchy or burning skin
    pink or red skin discoloration
    joint and muscle pain
    swelling of limbs or whole body (edema)
    facial flushing
    urine discoloration
    increase in blood volume and red blood cells
    low potassium levels
    gout flare-up

  28. Thank you doctor for giving answer on vitamin b12 deficiency. I suffered from low levels it was just 142, I have undergone with so many treatments like injections and pils but due to high weakness, vomiting, itching, rashes, dizziness in my body I am unable to get cure with this treatments. Later, I started taking super mic b12 shots it is liquid supplement and lipo shots are nowadays highly demanded I think. Guys I suggest you to please take healthy diet and nutritiens in your daily routine otherwise you have to feel these symptoms and it literally tooks time to cure the low levels of b12 to high more than 200.

  29. I am able to cure my B12 deficiency through a lipotropic liquid supplement. I have taken B12 pills for one month and it doesn’t have higher results so I stopped it and bought Buy MIC B12 from an online store.

  30. Regarding vitamin B12 types, Dr Greger suggests Cyanocobalamin instead of Methylcobalamin. The Cyanocobalamin is the manufactured form and contains a cyanide molecule. The Methylcobalamin is a natural form. I started looking up B12 types and want to ask Dr Greger why he recommends Cyanocobalamin over the natural Methylcobalamin? I did buy the Cyanocobalamin but a little apprehensive about it now.

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