The Dr. Is In: Taking the Mystery Out of Vitamin B-12


OK, first of all: absolutely fantastic responses to Courtney and Sarah’s thoughtful and illuminating guest post! This was a departure from the usual Green Recovery story, to be sure, but I think it was one of the strongest entries so far. I appreciate all the comments. The post has also inspired me to write a post I’ve been meaning to write for a while, on sex/sexuality and ED recovery, so you can expect that before too long.

I’ve got another guest post for you today, but this one’s in a totally different vein. For a long time now, I’ve been hoping to start a “ask your doctor” series here on CR, in which I ask a real life physician to answer some of my readers’ most pressing health and wellness questions. I do the best I can when I get health inquiries, but my knowledge base has limits (hence the whole post-bacc/med school thing), and there’s nothing I hate more than posturing as an expert when I’m missing the necessary expertise. So from now on, I’ll be fielding certain important health inquiries to an MD who’s capable of explaining the answers to us simply and informatively.

That MD is my good friend, Dr. Stuart Seale. Dr. Seale first commented on my blog about a year ago. At the time, I was toying with the idea of a career in medicine, but I was still too riddled with doubts to take it very seriously. Months later, when I was ready to commit to a post-bacc, I sent Dr. Seale a very candid (and, I daresay, helpless) email voicing some of my biggest fears: was I too old? Would the debt crush me? Would I be able to have kids in my thirties, if indeed I wanted to? And so on. Dr. Seale responded with what is by far the most insightful and inspiring email I’ve ever gotten from a near-stranger, urging me to pursue this crazy plan. We’ve been correspondents and supporters of each others’ work ever since, and I hope I’ll be able to rely on Dr. Seale’s expertise and confidence as I continue my studies (especially as I head into my Orgo/ Bio year—he was a biochem major!).

In the future, I hope to get Dr. Seale’s opinion on some complex and unexpected nutrition topics, but I decided to start with basics: B-12. It’s the Vitamin I am most often asked about (for good reason; it can’t be supplied in a vegan diet without either supplementation or certain fortified foods), and no matter how many times I offer up the standard feedback, readers continue to be confused about it. For instance, they wonder how “natural” a vegan diet can be, if it lacks an essential vitamin? I’m so glad to have Dr. Seale here today to put some of our concerns to rest, and so that he can give us some essential tips on how to supplement properly.

Without further ado, the doctor is in.

Taking the Mystery Out of Vitamin B12 by Stuart A. Seale, M.D.

Stuart Seale HiResFor those who follow a plant-based diet, it’s not uncommon for friends and family to voice concern over a number of nutritional issues that aren’t grounded in fact. “Where will you get your protein?” or “You’ve got to drink milk to get calcium!” are comments often heard. In the same vein, when it’s learned that a vitamin B12 supplement is routinely recommended for vegetarians, and especially vegans, many are quick to conclude that a plant-based diet is inferior. After all, if a total plant-based diet is so healthy, then why doesn’t it supply all essential nutrients and micronutrients? This has led to confusion, even among vegans. So let’s take a look at the science regarding B12 and dispel some myths along the way.

Vitamin B12 functions as a co-factor in numerous metabolic and physiologic events critical to human health. It plays a role in the proper production of red blood cells, and a deficiency can lead to megaloblastic anemia. Vitamin B12 is also vital for proper nerve function. Without it, various neurologic and psychiatric symptoms such as numbness, weakness, shakiness, unsteady walking, mood disturbances, and even dementia can develop. There is also good evidence that vitamin B12 improves vascular health because of the role it plays in reducing blood homocysteine levels. High homocysteine can damage arteries, increasing the risk for heart attack and stroke. Other effects currently being researched include the role of vitamin B12 in reducing the risk of breast cancer, cholesterol, and stroke recurrence.

Vitamin B12 is an essential micronutrient for humans. “Essential” means that it must come from external sources – we can’t manufacture it in our bodies using other nutrients as building blocks. The vitamin, in its full form, must therefore be supplied dietarily. This fact is what creates a potential rub for vegetarians, because no plant foods serve as a reliable source for B12. It’s only found predictably in animal foods – meat, eggs, and dairy.

Does this mean that we weren’t designed to be vegetarians, and that plant-based diets are inferior? In order to answer these questions, we need to look at the ultimate source for all vitamin B12, which is bacteria. The vitamin is made in nature only by bacteria that reside in soil, the upper intestinal tracts of ruminant animals (cows, sheep, deer, etc.), and also the lower intestines of animals. In the case of ruminants, the B12 that is made by the bacteria residing in their stomachs can then be absorbed into their tissues. In addition, the food they eat is contaminated with soil, which contains vitamin B12. Livestock are also fed B12 fortified foods to boost tissue levels. For wild, non-ruminant vegetarian animals there likely is enough ingestion of bacteria from foods contaminated with soil to provide adequate B12. In the case of wild, carnivorous animals, B12 is supplied from the liver (the animal storage organ for excess B12) and the intestinal bacterial of their prey.

The daily requirements of B12 for humans is very low, and in the past when we didn’t live in such a sterile and germophobic society it is likely that soil and other bacterial contamination of plant foods provided all the B12 needed. But our environments are different in the modern age. We are not only living much more sanitarily and bacteria-free, but our agricultural soils have also become sterilized. Of course, there is still the bacterial production of B12 in the lower intestinal tracts of animals, including humans, but we can’t absorb the vitamin from that location. However, undoubtedly much of the B12 found in animal foods is derived from intestinal bacterial contamination during the slaughter process.

There is an abundance of nutritional research demonstrating the benefits of eating whole plant foods, even if no animal foods are included. Humans are perfectly capable of eating a totally plant-based diet and maintain superior health while doing so. In our former agrarian society when bacteria-rich soils were worked by hand, there simply wasn’t an issue with humans getting enough B12, because it was supplied by soil contamination of our foods and skin. The issue of vegans requiring vitamin B12 supplementation is therefore not an indicator of a plant-based diet being inferior or unhealthy. The two really have nothing to do with each other. The fact that modern vegans require B12 supplementation is related to the sterility of our environment, not to the overall nutritional quality of the foods we eat. Humans haven’t changed, but our environment has.

To be certain vitamin B12 deficiency doesn’t occur, taking a supplement of B12, as little as 25 to 100 micrograms per day, is all that’s needed. Larger doses, up to 1,000 micrograms per day are commonly recommended but probably not necessary. Supplements of B12 may be labeled as cobalamin, cyanocobalamin, or methylcobalamin and there will be very little difference regarding their effectiveness when taken routinely. While both vegetarians and vegans should supplement with B12, it’s even more critical that vegans take a supplement. Some are adverse to taking a supplement produced from a bacterial source, but look at it this way – you’re getting in a purified pill form what our ancestors got from under their fingernails.

Enjoy all of the benefits of eating plant-based: less tendency for being overweight; lower risk of heart attack, stroke, hypertension, cancer, and chronic disease in general; and being kind to the environment and other living creatures. Just don’t forget to take your B12!

Stuart A. Seale, M.D., Diplomate American Board of Family Medicine, graduated from Loma Linda University School of Medicine in 1979, then completed a Family and Community Medicine residency at the University of Missouri in 1983. He established and maintained a solo office family practice in Springfield, Missouri for 21 years before joining Ardmore Institute of Health as Clinic Director, educator, and staff physician for Lifestyle Center of America. He is currently Vice President and Chief Medical Officer for Ardmore Institute of Health, as well as Medical Director for AIH’s Renovo Clinic in Gilbert Arizona. He is also an Adjunct Assistant Professor in the Department of Preventive Medicine at Loma Linda University School of Medicine. He joined the American College of Lifestyle Medicine in 2006, and currently serves on the Board of Directors for the ACLM Foundation. Dr. Seale has a passion for treating chronic disease through lifestyle behavior modification, and wishes to influence the practice of medicine in America, as well as American culture itself. To this end, he has co-authored two books related to healthy lifestyle – The 30-Day Diabetes Miracle, and The Full Plate Diet. He and his wife Sandra reside in Sedona, Arizona.

Fabulous post, Dr. Seale! And useful for me, too. In my first couple of years as a vegan, my B-12 levels were always off the charts, in spite of the fact that I rarely supplemented and drank few fortified beverages. So I got into the lazy habit of not taking a supplement. Lately, I’m more determined to take at least a moderate dosage, because even if my body seems to store B-12 for the moment, that won’t be true forever, and there’s no harm in prevention.

OK, friends, this part’s exciting: now that we have Dr. Seale as a regular CR contributor, I welcome you all to send in questions (you can email them to me, or tweet me, or you can leave comments on this post) that you’d like for Dr. Seale to respond to. Of course I still welcome you to send me questions regarding nutrition, cooking, raw food, ED’s, and female health, but be aware that you now have another resource when it comes to hard questions about biology and medicine.

Also, I encourage you to get to know Dr. Seale in person. His twitter handle is @DrSeale, his blog is Dr. Seale Weighs In, and you can read about his work at the Renovo Clinic, where he helps to share his passion for chronic disease prevention and treatment through lifestyle choices, here.

Send in those questions. And please, wish me luck: after five warp speed weeks, my big chem final is tomorrow at 8 am!


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  1. Useful article and discussion! It would be really interesting to know more about what other vegan pregnant/nursing women are doing with B12 supplementation.

    I am a vegan pregnant woman only about 3 weeks away from giving birth – I have been vegan for about 3 years now and had not taken b12 blood tests so far. However, I have mostly been taking a b-complex tablet ever since I became vegan. I have missed it several times but not worried since I consumed fortified foods as well.

    However, since finding out that I am pregnant, my daily vitamin routine has always included a b-complex tablet (I live in India where you dont get a single prenatal, but doctors prescribe tablets for iron, calcium, folic acid etc. You also do not get reliable B12 fortified foods in India, supplement is the only way to go). In the first trimester, my dosage was mostly 300 mcg/day and in the next two trimesters, I took a b-complex with 15 mcg/day.

    I had my b-12 levels checked using the serum b12 blood test @ 36 weeks (not tHcy or MMA) and found my levels to be 298 pg/ml. I have now started taking a 1500 mcg mecobalamin sublingual every alternate day, just to be on the safer side.

    All the medical literature I have read so far have shown results that B12 levels drop significantly during pregnancy, especially towards the end. In literature, even for control group subjects with non vegan diets, typical B12 values are less than my 298 pg/ml…because of which I am not yet alarmed. I thought I’d mention this and see if there are other women like me who have had their B12 tested during pregnancy. I will continue to take the daily b-complex (with 15 mcg) and the 1500 mcg sublingual for some time to come, to ensure that my daily intake of B12 is more than adequate while I am nursing.

  2. This post is golden!

    However, the only thing I would add/change is that not only “wild” carnivorous animals need Vitamin B12, as well as other nutrients, directly from the prey, but ALL carnivorous animals, domestic or wild do need to feed on a Biologically Appropriate Raw Food diet (B.A.R.F.).

  3. I realise this is a super old post but I find this so interesting just reading it!! I actually suffer from amenorrhea now despite eating a meat diet for a year after recovering from anorexia. The more I track back the more I love this blog ๐Ÿ™‚

      • ๐Ÿ™‚

        I tried progesterone to restart my periods and sadly I only had one very light one afterwards and then it stopped ๐Ÿ™ 4 years without a period is not great! As I don’t have PCOS I’m thinking it is just a case of gaining more weight now (BMI 19.2). Again – I find your blog so valuable ๐Ÿ™‚

  4. Hi Dr. Seale …

    I am SO glad you are talking on a subject that is very high on my list of concerns.

    I went strictly vegan in 2009 and didn’t supplement with B12 at all until about a year ago I began having all the symptoms of B12 deficiency (bleeding gums, headaches, nausea (no vomiting just felt “off”), constipation, etc) and started supplementing with 2000 mg sub-lingual tablets daily for about 2 weeks. All symptoms vanished after just a few days of that supplementation.

    I try to take a weekly 2000 mg dose … but if I don’t then I almost immediately get a return of the deficiency symptoms.

    Can you advise if there might be something else going on? I always know when I have forgotten to take a dose within a day or two of forgetting. It is rather distressing and I admit makes me consider giving up vegan for vegetarian.

    Thanks in advance!!

    • Hello Melissa – I’m going to assume that you had a normal B12 level prior to becoming vegan in 2009. Of course, that may not have been the case and unless you had lab tests done there really isn’t any way to know at this point. However, if you had normal B12 in your body prior to becoming vegan, it is very unlikely that you would become deficient in a 1 year period of time. The body only uses about 2 or 3 mcg of B12 per day and it would likely take most people several years to deplete their B12 stores. The symptoms you describe are not those normally associated with B12 deficiency, and even if they were related to low B12 they wouldn’t have disappeared within a few days of supplementing. Having an immediate return of symptoms if you miss a dose of B12 also sounds very atypical. Unfortunately, your symptoms are non-specific and could be caused by a number of things, and it’s hard to tell if any of them could be serious. I’d really feel better if you were evaluated by your doctor and perhaps have some basic blood tests done, should she/he advise doing so.

      • Thanks for such a speedy reply … really good information to know. I will get to my doc and find out what is going on … though not looking forward to what I always know is coming whenever I mention I am vegan.

        I definitely have no idea if I had normal levels before going vegan (tho I was a heavy meat eater) but never had those symptoms before going vegan. The symptoms I am getting are those I found listed on the WebMD site (and other medical reference sites) … so that is why I thought I had B12 deficiency symptoms.

        Thanks again!

        • I just wanted to let the good doc know that I went to my doctor and was checked out. It seems I have pernicious anemia. (apparently so did my grandmother … just found that out from my mother for the first time this week).

          So thank you for your advice … on the road to getting healed!

          • Thank you Melissa for the update. I’m very glad you got this properly diagnosed and are getting treated. It’s important for you to know that this condition would have happened regardless of your diet, so for best health also continue eating vegan!

  5. I really appreciate the detailed discussion you provided here, Dr. Seale. (And thanks for giving us access to him, Gena!) I’ve always felt my answers to the B-12 question were a bit wishy washy. Now I’m all set! ๐Ÿ™‚

  6. Bonnie – I don’t think you have much to worry about, so long as you’re not living solely on raw kale salads and other brassica (cruciferous) veggies such as broccoli, bok choy, brussel sprouts, cauliflower and the like. As with all things nutritionally, moderation and variety is key to good health. There are compounds in the brassicas that interfere with iodine uptake by the thyroid, however this is mostly a concern if the diet is deficient in iodine to begin with. An excellent source of dietary iodine is sea vegetables. I feel that if you eat a variety of foods, including sea vegetables such as kelp or dulse (maybe add them to your kale salad!), then you should be fine. Of course, if you notice signs of hypothyroidism (excess fatigue, intolerance to cold, thickening of the hair and/or nails, or swelling in the front of the neck that could be due to thyroid gland enlargement) then you should have a blood test done to evaluate your thyroid health. The most sensitive test is a TSH.

  7. Hi there, I’m interested in the role raw brassicas supposedly play in stripping iodine from the diet. I’ve read this in several places recently but I love my raw kale salads – can you please help?

  8. A great post for anyone following a plant based diet. It’s very easy to think you don’t need to supplement with B12, because it takes such a long time to actually develop a deficiency. Our body is very good at “recycling” B12 as an enzyme cofactor – I think something like 95% or higher gets recycled. But by the time you have symptoms of a B12 deficiency, you could be doing yourself great harm. And for vegan/vegetarian females wanting to have children it’s even more critical, because your child will be getting their B12 stores from your breast milk.

  9. I went about 7 years as a vegan without supplementation. It wasn’t until this January when I experienced a 6-week long bout of the flu that I started to experience pretty severe anemia and resulting energy issues. After 4 months of committing to iron and B12 supplementation, I’m feeling so much better!

  10. I’ve always wondered about B-12 and its role in vegetarian and vegan diets. Thank you so much for this easy to understand explanation, Dr. Seale! Gena, I’m so happy you’re going to make this a recurring feature!

  11. Thanks for such a great and informative post!!

    Dr. Seale, if you are still answering questions on this post, I have a few.

    1)My husband and I are landscapers and are constantly “playing in the dirt” and we’re curious to know if it is possible to get sufficient B-12 thru these means? The ground that we normally work in would probably not be considered “sterile”.

    2)Is there a comprehensive list of vitamins that people on a plant-based diet may be deficient in?

    Look forward to more of your input and articles thru Gena’s site. Thanks for time and knowledge!

    • Kimberly – while you’re undoubtedly getting skin contamination with vitamin B-12 producing bacteria, you’ll need to ingest it in order for it to do you any good. So, it would depend on how “clean” you and your husband are – I don’t intend this to sound glib or tongue-in-cheek. It’s just the way the process works. It could be that you’re doing very well with B-12 assimilation, or it could be that you’re not doing well at all. The only way to know for sure is to get a blood level as a baseline and then keep an eye on it periodically (every 6 to 12 months, depending on the initial level – at least 400 and preferably closer to 1,000). If it’s declining, then a supplement would be a good idea. The only supplements I routinely recommend for those on a vegan diet are vitamin B-12 and vitamin D. Neither one of these is supplied by plant foods and both are critical to health. Vitamin D can be obtained from sun exposure to the skin, and since you work outdoors this may not be an issue for you – however, the only way to know for sure is to be tested. You want your 25-hydroxy vitamin D level to be above 40.

  12. Dear Dr. Seale and Gena,

    I’m a little late, but thank you so much for this highly informative post!

    I just got back from visiting my mom in northern California (I currently live in Ohio), and I was astounded at my options for vegan dining. That said, no one else in my family nor my boyfriend are vegans or vegetarians so the questions about eating a plant-based diet continued all week (which is great!). I think one of the most important questions tends to be something along the lines of ‘what is so great about your diet versus mine?’, especially if the person asking is thin or not having very apparent health problems to begin with. As I start to explain, then the questions come as to how you get your sources of this, that, or the other nutrient. Dr. Seale, you bring up an issue that for me seems difficult to explain to others, that is, that our food and its sources has changed but humans have not (at least much). Because we are able to eat a variety of foods and not get violently ill or die (right away, that is), and because we can mass produce foods, livestock, produce, etc. quickly and cheaply doesn’t make us particularly cunning or evolutionarily greater than other animals (we’re just different). Furthermore, it doesn’t mean that we should eat those foods. What is lucky, I feel, is the production of some nutrients synthetically so that we are able to adjust our lifestyles according the research and vast amount information available to us (though it’s hard to sift through!).

    Anyway, thank you again for sharing this information in an easily digestible (ha…) format. And Gena, thank you for posting it and also advocating for a wide variety of foods to be cooked, uncooked, and discovered with the goal of whole, optimal health.

    • Colleen – better late than never! Something to try the next time you get into a Q&A session with others who want you to perhaps defend your nutritional beliefs is to turn the tables by asking them why an omnivorous diet is superior to one that is totally plant-based. In other words, what nutrients (macro or micro) are obtained from animal foods that are unavailable from plants? With rare exceptions (the 2 notable ones are vitamin B-12, which is actually made by bacteria; and vitamin D, which is made by humans and other animals when their skin is exposed to sunlight), there are none. The main macronutrients to be had from animal foods are fats (primarily of the bad variety – saturated fats) and proteins (which are in amounts beyond human needs for good health). The primary micronutrients are minerals, especially iron from heme (blood) sources. While better absorbed than plant iron, it is also more damaging to the body because of it’s oxidative nature (it produces free radicals in the human body). In addition, animal foods are contaminated with toxins, pesticides, and antibiotics. It really isn’t necessary to defend to others why you eat the way you do – science will do that for you very well. Instead, ask them to defend what they do (in a nice way, of course!).

      • Dr. Seale,

        Thank you for taking the time to reply! I never thought about turning the tables around, and mostly just find myself spewing synthesized information from numerous sources (which isn’t always the best way of informing someone… only confusing them and creating frustration on both ends). Thanks for the guidance!

        • Colleen – some additional info that may be useful for you when you talk to others who aren’t as enlightened as you nutritionally – I mentioned above all of the negative items encountered when eating animal products, but I didn’t list the highly beneficial nutrients that AREN’T obtained. These would include healthy fats (mono and polyunsaturates), fiber (consider fiber as an indicator of a food’s overall nutritional quality – there is absolutely no fiber in any animal food), antioxidants (very little in foods from animals), and phytochemicals (like fiber, there’s zero in animal products). So, who should be worried about who?

  13. Thank you soo much for your reply! It was just the motivation I needed to get a couple of other things checked out as well. I’m also going to work on adding more of the foods you mentioned. Thanks again Dr. Seale!!

    (And thanks to Gena for this awesome forum!)

  14. I am 20 years old & I have been a strict vegetarian for about 6 months, but I have never eaten much meat at all when growing up – just don’t care for the taste or texture. I’ve been feeling great for the most part – my skin, hair, and nails have all been looking fantastic! I haven’t been sick or had a cold at all in 2011, when I am typically used to getting sick several times a year! I have also been working out fairly regularly this year for the first time in my life (but I am & have always been a healthy weight).

    My question is — In the past 3 weeks I started noticing that my fingernails are turning purpleish. They are clearly half pink / half purple, divided by a horizontal line on every nail. I think this might be an iron problem, as I have also been pretty tired lately, but I’m also an undergrad student ๐Ÿ˜‰

    I want to take a vitamin with B12, iron & folic acid, but I noticed that multivitamins provide a pretty low B12 level (6 mcg I believe) & the B-complex vitamins I’ve seen don’t have any iron. What should I take?

    Thanks so much!!

    • Hannah – without actually seeing your nails it would be hard to say what may be going on there. It doesn’t sound like an iron issue, as that would typically cause paleness to the entire nail bed. There’s no point in trying to guess whether or not you have an iron deficiency when there are lab tests that will tell you definitively. The same is true for the B-12. I’d recommend you get a serum iron, TIBC (total iron binding capacity), vitamin B-12, and a CBC (complete blood count). Those tests should tell you if you’re anemic, iron-poor, or B-12 deficient. If you’re B-12 is over 400 or 500, then the 6 mcg per day in your supplement should keep you there, but I’d still recheck it every year. Also, if your iron and hemoglobin levels (the hemoglobin will be on the CBC) look OK and if you’re not donating blood or having abnormally heavy periods, then eating iron-rich plant foods (nuts, seeds, beans, lentils) along with foods loaded with vitamin C (red bell peppers, kiwi, strawberries, citrus, broccoli, cauliflower, sweet potato) should be adequate, without supplementing iron.

  15. This post is just perfect timing for me. I have been on a high raw vegetarian diet for the past 14 months and in February I went completely vegan. During my annual physical a month ago I found out my B12 was at its lowest point (116). I can’t blame the vegan diet as I’ve been low on B12 for about a dozen years. My doctor started me on B12 shots right away and I’ll be taking those monthly and checking my progress to determine if that will be enough. Considering my previous diet was very heavily laden with both meat and dairy, I suspect I have some sort of inability to properly absorb B12. Are there any other suggestions you may have for me? Thank you so much for this insightful and educational post.

    • Michelle – I’m very glad that you and your doctor had the good sense to check your level, and that you’ve taken a course of action! Since you’ve been eaten a lot of meat and dairy in the past and it evidently has been low for some time (assuming you were eating animal products during the time it was low), it is possible that you have an intestinal B-12 absorption issue. In order for vitamin B-12 to be absorbed from the small intestin, intrinisic factor must be secreted by cells in the stomach and then bound to the B-12. Some individuals don’t secrete intrinsic factor and therefore B-12 isn’t adequately absorbed. There is a special test to diagnose this, the Schillings test, however I’ve found that pragmatically it doesn’t really matter because the treatment is the same regardless of the Schillings result – you have to take B-12 by injection, intranasal, or sublingual routes in order to get the vitamin directly into the blood without going through the intestinal tract. I’d want you to get your B-12 level up as fast as possible, so please discuss with your doc the possibility of getting a shot of 1,000 mcg of B-12 every WEEK for 4 to 6 weeks, then every other week for 4 to 6 injections, then monthly for another 4 injections. At that point I’d get another B-12 level as well as serum homocysteine and MMA tests (your doctor should know about these). These tests will determine whether you’ve been adequately repleted with B-12. If so, then you could stop injections and switch to sublingual drops or lozenges of 1,000 mcg daily while checking B-12, homocysteine, and MMA levels every 3 to 6 months until you know the sublingual route is doing the job. If not, then you may need monthly injections indefinitely.

      • Wow! Thank you so much for all the good information! I will talk to my doctor about that. I don’t mind getting the shots so It’s simply a matter of scheduling the appointments.
        I started these dietary changes 14 months ago for a number of reasons including weight and health issues. I saw my doctor when I started and then again a month ago. I’ve lost 72 pounds and this isn’t the place to talk about all of the health changes and benefits I’m experiencing but suffice it to say that with the exception of my B12… I absolutely aced my exam! Thank you again. I have been trying to use good science to guide me on this journey and you have been helpful.

  16. Thank You so much for this post! I’ve been so confused about B12 for a long time and was always hesitant to try out a complete-plant-based diet. I was always doubting that it was “unnatural.”
    Now that I have one more resource to contemplate about!

  17. thanks for posting this! B-12 can be confusing. I will bookmark this and go over it with Michelle when she gets back in town. We try to take supplement for it but never remember to take it

  18. This post is just perfect timing for me. I have been on a high raw vegetarian diet for the past 14 months and in February I went completely vegan. During my annual physical a month ago I found out my B12 was at it’s lowest point (116). I can’t blame the vegan diet as I’ve been low on B12 for about a dozen years. My doctor started me on B12 shots right away and I’ll be taking those monthly and checking my progress to determine if that will be enough. Considering my previous diet was very heavily laden with both meat and dairy, I suspect I have some sort of inability to properly absorb B12. Thank you so much for this insightful and educational post.

  19. I think it is worth pointing out that B12 deficiency isn’t exclusively a vegan issue. It affects the whole population, as the ability to assimilate it decreases with age (from about 50 years on).

    Many folks in nursing homes are terribly B12 deficient, and it is very unfortunate that it remains seen as a predominantly “diet” related issue. It benefits neither vegans to be seen as people with “unnatural” diets needing supplementation, nor the general population who, for fear of being tarred with the “weirdo” brush, keep the B12 deficiency epidemic in the closet.

    Just my two cents worth and no offence meant; it is one of my bugbears though.

      • Hi Gena,

        Contrary as ever, I’m afraid…I’m happy to see how well things are going for you though. Wishing you all the best!

    • Susie – you’re right – it’s not exclusively a vegan issue. This is the reason I check B-12 levels on all my patients, regardless of age or dietary habits. I find that many have sub-optimal levels and need to be on supplementation. That underscores my point that it really isn’t strictly a dietary issue as much as it is an environmental and social/cultural one.

  20. as a pre-medical student struggling to finish my last few secondary essays,I just want to say THANK YOU to Gena, Dr. Seale, Nicole and Daphna for reminding me that the medical community is DIVERSE and includes the representation of compassionate physicians who understand the power of preventative medicine and letting food be thy medicine!

  21. Thank you so much for this post! I feel it is really important that for any kind of diet to be sustainable one needs to assure that they are getting the proper nutrients. B12, vitamin D, calcium, iron, etc. are all ones that it is really helpful to read up on. I look forward to following all of these posts (along with Gena’s normal ones, of course!). Thanks again!

  22. great post and exciting new series! thanks for the info, Dr. Seale. I’m a vegan who takes a B vitamin supplement one or two times per week, so maybe I’ll start trying to take it more regularly.

  23. Hello Dr Seale and Gena,

    Thanks to you both for such an informative post. As a relatively new vegan, I am still having to ‘explain myself’ to friends and family, and this helps to support my decision. It also helps me too, because I’m quite a ‘binary’ person, and found it difficult to reconcile that a vegan diet could be lacking in anything. This helps to define why vegans are advised to supplement or eat fortified foods, and the reasoning behind why this is most applicable to modern life.

    With best wishes,

  24. First, good luck on your exam, Gena!!

    Second, this is great…..there should be more “ask the doctor” posts!! My B12 level showed about 200 a year ago. And I just read on another blog that one should take pretty high doses….so I bought the 5000 mcg chewables of Methylcobalamin. I took those for about 5-6 days but really didn’t feel good after that, so I stopped. Is it too much? I thought you couldn’t take too much B12. I also have 2000 mcg that you put on your tongue….maybe I should try those, but not everyday?

    • Tanya – if your level was 200 a year ago, I’d get it checked again now to see where you’re at. This is critical – please do it soon. It doesn’t sound like you’ve been taking regular amounts of supplementation in the interim, so I suspect your level is still very low. For supplementation, there’s generally no need for more than 1000 mcg per day, but you could use the 2000 mcg lozenges you have available until they’re gone (go ahead and use them every day), then switch to 1000 mcg per day after that (also in your case I’d go for the methylcobalamin variety over cyanocobalamin because it’s better absorbed). PLEASE get your level checked again (pronto!), start taking the supplement as described above, and get another B-12 level checked again in 3 or 4 months to be sure it’s responding to treatment. If not, and if it’s still in that 200-300 range then you may need injections of B-12 in order to get it to where it needs to be. If shots are necessary and you get your level up (over 500 or so), then at that point you could probably go back to oral supplementation. Please don’t ignore this – the consequences are too potentially serious.

      • Thank you for such a quick response! And…the sad thing is…according to my results on paper that I got (a year ago), it says that I’m in the NORMAL range! By the way, I was the one to ask for the B12 test….my doctor did the regular tests only, plus a vitamin D test (which I now take 50,000 per month).

        I will definitely go in for a blood test again soon, before the summer is over. And I will start with those 2000 mcg. Thanks!!

        • Also recheck your 25-hydroxy vitamin D level. At 50,000 units per month you may be OK, but I’d like for you to be sure you’re not getting too much. Ideal range is 40 to 75 for vitamin D (25-hydroxy).

  25. Great post – informative and simple enough to understand – I am sending it to everyone. Thanks to Gena and Dr.Searle.

    I would love to to read a post on vegans and Vitamin D – last winter, I took Vitamin D2 (NOW Supplements)and I am going to stick with the D2, but there seems to be a lot of controversy on its effectiveness compared to D3. From what I’ve read, it seems that D2 does not stay in the body as long as D3 when you stop supplementing. Would love this one cleared up by an actual medical expert.

    Also would love a post on vegans and iron! I’ve had no issues with iron since being vegetarian then vegan, but family and friends often question “how vegans can absorb plant iron” even though I eat copious amount of legumes and have always had good levels when checked.

    • Nadine – it is correct that D2 (ergocalciferol) isn’t absorbed as well as D3 (cholecalciferol) – in fact less than 1/3 as well. Once in the body, I don’t know of any difference in terms of excretion between the two, but it’s possible that could also be a factor. One of the reasons pure vegans may take D2 instead of D3 is because D2 can be obtained from plant sources while D3 usually is sourced from fish oil, fish liver, or sheep’s wool lanolin. If a vitamin D supplement is taken, I think everyone needs to determine which product (D2 or D3) fits best with their individual health objectives and lifestyle choices. Regarding the plant iron question you’ve been confronted with – the next time family or friends ask you that one, answer them with a question of your own, “Where do you think the cow got the iron that’s in the red meat you think I should eat?”

      • Thank you for your reply Dr. Seale (Sorry for the initial typo I was a bit tired). I use D2 as I feel most comfortable with non-animal sources of food and medicine. I also keep an eye on my levels, which have been good so far (6+ years).

        Re: The iron question – I will keep that line in mind for future conversations! LOL

  26. Gena, thanks for the informative contribution from Dr. Searle. I think the “Ask the Dr.” column will be a great addition to Choosing Raw. That said, I wouldn’t shy away from writing about whatever medical or nutritional topic interests you just because you aren’t, yet, an expert. For one thing, experts disagree. But for another, no one expects you to be an expert. I think you can approach these topics like a journalist and share your understanding of the available data. I’m as capable as the next person of accessing the scientific literature on the topics you write about. Yet, one reason I read your blog is because I appreciate seeing those topics filtered through your personal experience. In fact, I’m very glad you chose to evolve your blog in the direction you did, because if my memory is right, when you started out, I think you were writing more as “clinical nutritionist” than “Gena.” All well and good, you are an amazing writer, but I appreciate the window into your life as much as the information you provide.

    • Elizabeth,

      The relationship between informing and sharing has always been a tricky one for me as a blogger! I like to be informative, and to my credit I have studied nutrition and gotten a degree. But I also like to be intimate (that took me a while, as you noticed, no doubt). And on top of this, starting to take higher level nutrition and science classes has shown me how little I really know about how the human body works, and it has also forced me to examine and reexamine some of the assumptions I used to make about nutrition science. Every fundamental remains constant, but the details have often been called into question or reshaped. It’s exciting, but it makes me wary of presenting myself as an authority when in fact I feel very much like a student who is just beginning her education.

      So I guess the upshot here is that it’s good to know that many of my readers *want* to hear from Gena, the student of nutrition and medicine, because I do have information and personal experience to share. But when it comes to these kinds of specific questions, it’ll be good to enlist the help of someone who’s a little further down the student road than I am ๐Ÿ™‚

      Thanks for calling attention, as you always do, to something that’s worth thinking about and also a source of conflict for me sometimes.

      G xo

  27. I grew up spending my summers in a real Russian village, where for many years we had to go to a well for water and all the farming was by necessity organic, so I suspect I got a lot of B-12 from the soil. It makes me wonder, when I buy root vegetables from farmers markets from local biodynamic or organic farmers, I do always rinse it and will continue to do so, but rinsing is different from scrubbing with soap and ensuring that all dirt is gone.

    I saw a comment above about the benefits of our sterilized lifestyle and how you should still wash hands after bathroom, and I agree with it overall, but I still wonder if not worrying about dirt from relatively known sources could be a good thing, in terms of risk/benefit ratio. I guess, I am biased by my childhood of drinking raw milk from neighbours cow who was grazing freely by our house and milked by hand; by picking a carrot from the ground, rubbing it on my clothes and eating it, and never getting sick… and I do realize they are anecdotal experiences not reflecting true risks and rates of food-borne diseases. But they still bias me and make me wonder if trace dirt on my radishes that came from a responsible local farm is okay.

    • InaG – probably my best response is to tell you what I practice myself. I don’t go overboard when washing fruits, veggies, root veggies, etc. and I always try to buy organic locally grown (especially when it comes to the “dirty dozen” list put out yearly by the Environmental Working Group). I usually scrub my root veggies with a brush under the tap and I eat them unpeeled. If there’s obvious dirt I get it off, but that’s about it. I do it this way not to try and get my B-12 in this manner, but rather to reasonably try to get potential pathogens off of the food. But I also take a B-12 supplement on a regular basis because I have no way of quantifying how much B-12 I may be getting by prepping my food the way I do.

  28. Thank you Gena & Dr. Seale! The whole B12 issue has weighed on my mind a while as I’ve waffled between a vegetarian and vegan diet. My question is about the way to take B12-I recently listen to a raw food lecture saying that we pee out 99% of oral viamin B12, but we can absorb 100% through a B12 patch on the skin. Your thoughts? It sounds a little crazy to me, but I don’t want to think I am wasting away all my vitamin b12 every day by taking it orally. Also, if I take a multi with B12, do I need an additional supplement?

    Thanks again for this great post and I’m looking forward to future Dr. Seale visits to CR ๐Ÿ™‚


    • Kate – it really doesn’t matter what the delivery method to the bloodstream is. It can be from intestinal absorption of swallowed B-12, trans-mucosal absorption from being taken under the tongue or even sprayed intranasally, or trans-dermal absorption from a skin patch – the vitamin must get into the bloodstream in order for it to be effective. It also doesn’t matter what the route of delivery is in terms of what happens to excess B-12 in the bloodstream – it is first stored in the liver and when the storage sites are filled, the excess is then urinated out of the body because it’s a water-soluble vitamin. I’m wondering – were they selling B-12 patches at the talk you attended? :o) If your multivitamin has at least 5 mcg of B-12 in it, you’re probably OK if you take it daily. But I always feel better when a baseline B-12 level is checked and then monitored yearly so you can catch it if it starts to decline.

  29. This is so interesting! As a fellow vegan and nutrition student, I am surprised that I have not learned this information in my personal studies or in school. Thank you, Dr. Seale for this wealth of information and thorough explanation!


  30. Like Tiina McKay’s comment, I’m also curious if the b12 in nutritional yeast is a sufficient source.

    • Hi Anne – I hope my answer to Tina will suffice. Bottom line – check your numbers and follow them. It’s the best way to know how you’re doing.

  31. Thankyou so much for this, it’s such a useful thing to read – and great to read these kinds of things directly from a doctor! I tend to have fortified soya milk daily and take a multivitamin a couple of times a week.

  32. Thank you very much for this post. Was just wondering if the doctor could clarify some questions about absorption of B12 supplements (and other vitamin/mineral supplements). I think the biggest one for me is: Do other aspects of your diet affect the supplement absorption? I am thinking particularly about drinking caffeine as I’ve heard that supplements shouldn’t be taken along with my morning coffee. If this right, then what kind of time lapse is needed? Are there other things (other supplements even) that inhibit vitamin B12 absorption. Thanks again!

    • To my knowledge, DS, coffee or caffeine isn’t an issue in terms of micronutrient or vitamin absorption. I can’t recall seeing it in the medical literature, and would love to review a scientific paper on the subject if you’re aware of one. Unless you’re being excessive, I’d say you can take your supplements while enjoying a morning cup of coffee, green or black tea without concern. I’m also not aware of any specific other supplements that would impair B-12 absorption when taken together.

  33. Fantastic post! I have definitely been one of those skeptics who has questioned and voiced her opinions on the validity of a vegan diet based on this very issue, well, until now! ๐Ÿ˜‰ Thank you so much for clarifying. What about consuming spirulina, B12 fortified nutritional yeast, seaweed, etc., daily, wouldn’t that be sufficient since the RDA isn’t even that high? Assuming of course we’re talking about a person with healthy levels of B12.

    And I second everything Casey said right above me. And thanks, now you’ve made me miss living in Loma Linda, lol! Hawaii still has a LONG way to go to get to that level of health consciousness… I definitely miss that community of health focused individuals, but I guess there are more work opportunities for me out here because of that ๐Ÿ˜‰

    Good luck on your final tomorrow Gena!

    • Tina – you may or may not be getting enough B-12 from the sources you mention. Unfortunately, it’s a guessing game when trying to get B-12 in this manner. Certainly, I recommend you keep consuming the products that you are because they are very healthy in and of themselves, apart from the B-12 issue. My best advice would be to get a baseline B-12 level and see if it is above 400 (the higher the better). If so, then keep doing as you are and get the B-12 level checked every year. If you’re losing ground and go below 400, then start that supplement! Loma Linda is a special place – one of the few “Blue Zones” in the world, where people commonly live over 100 years.

      • Thank you so much for the info Dr. Seale! Sorry if I gave the wrong impression through my words… I’m not actually vegan, or even vegetarian (I know I know, I’m reading the wrong blog, but I love it! :)). But my animal product consumption is quite low, so I am still concerned about B12, among other things. I’m also a blood type A so I worry about my ability to absorb it (yes, I’m one of those people that believe in those diets!). And who knows, I may come around to the whole vegan (or at least vegetarian) thing one day.

        I very much look forward to posts from you in the future! A big thank you to both of you for the work that you do!

        • Oh, and one more thing! I’m personally very interested in how appropriate vegan (or at least vegetarian) diets are for children and babies as I have a one year old son. I don’t know if enough people have interest in this topic for a completely separate post, but I thought I’d throw that idea and concern out there! ๐Ÿ™‚ Thanks!!

          • Tina – a vegan diet is perfectly suitable (I’d say preferable) for children! As long as there’s adequate calorie intake suitable for growth, along with balanced macro and micronutrients, then there’s not an issue. Giving a variety of beans (yep – even for babies – after weaning, of course), veggies, fruits, plant oils (nut butters, avocado, olives), and whole grains will provide what’s needed – and most importantly won’t give what’s NOT needed (cholesterol, saturated fats, toxins, antibiotics, and hormones). For infants and children, I would recommend a multi-vitamin daily – but that is the case even for those who aren’t raised plant-based. I also recommend 1,000 units of vitamin D per day for all infants and children, as there’s good evidence this will help prevent type 1 diabetes (please note – this is higher than the RDA for vitamin D in this age group. My recommendation is based on medical research literature). Vitamin D comes in a liquid preparation suitable for kids.

          • Thank you again so much! I have to say it’s very refreshing to hear a doctor promote vegan/vegetarian diets for children! I wouldn’t dare even think of mentioning the possibility of not feeding my son animal products to my son’s doctor, she’d be horrified. And it’s a bit easier to know what to do for myself, but I really struggle daily with how to best nourish my child. Nutrition is such a fledgling science and it’s so exciting to read all the new studies that constantly come out, but it can be so difficult to know what to do when it comes to doing the right thing for the little one. Lately I’ve been reading so much negative stuff about grains, it just feels like all foods are bad for you apart from local, organic, seasonal veggies! ๐Ÿ˜€ Clearly I have some work to do. Thanks for all your help Dr. Seale!

  34. As someone who is starting to go vegan properly for the first time (ie I gave up dairy in its whole forms some time ago and I’m now eliminating produce that contains traces or dairy ingredients), this is really very useful.

    A gushing thank you again for starting this Gena, and thank you Dr Seale, for the vegan-friendly advice!!

  35. Gena and Dr Seale, this is an excellent and well articulated post, thank you.
    Gena, as a fellow Health Counselor and Life Coach, it’s great to hear you say that you abhor nothing more than pretending to be an expert on something you’re not. I feel exactly the same and never suggest that I can give advice or support on anything I am not knowledgeable about. It frustrates me to see many people, especially in the health world where lives and well being can be dramatically affected, doing this.
    Dr Seale, it’s so wonderful to see a conscious MD take the stage on a website like CR. Thanks for your response!

    • Thank you for your support! I have to say, though, that having an audience such as Gena’s is an absolute delight – you all are so health and wellness oriented and constantly seeking more. It makes what I do a piece of cake.

  36. Good luck on your test tomorrow morning, Gena! I’m sure you won’t need it though, smartie pants ๐Ÿ™‚

  37. Great and wonderful informational post. Thank you, Gena, for touching on nutrients that can be frequently inadequate in a vegan diet- iron, b12, vD, etc. I really have learned so much by reading them and this one included.
    I don’t take any vitamins or supplements, but luckily my B12, iron, or VD haven’t even been low. After reading this, it makes me want to look into possibly taking a b12 supplement for insurance.

    I’d love to hear Dr. Seale’s opinion on prolonged amenorrhea for females!

    • I agree with Emilia on the prolonged amenorrhea- I can’t find much info on it online, especially for girls of a “healthy” weight

    • Emilia and Raychel – amenorrhea, as you probably know, is the absence of menstrual periods for at 3 months in a female who has previously been having normal periods. Prolonged amenorrhea is the absence of periods for a year or longer. If it happens during the adolescent years, then it is most likely due to the fact that the pituitary-ovarian hormonal “dance” hasn’t adequately matured. It can also occur in women who have taken hormonal contraception and have caused suppression of ovarian function to the extent that when they stop the contraceptive the ovaries take a long time to “bounce back.” There are also new hormonal contraceptives that have been designed specifically to suppress periods on an ongoing basis, without the typical cycling that most contraceptives have used in the past (I don’t recommend these). Prolonged amenorrhea also can happen in adults due to stress, or because of certain anti-depressant and anti-anxiety medications. Ovarian or pituitary tumors can also be a cause, even in women who are at a healthy body weight. Lastly, if through diet, extreme exercise, or a combination of both, there is a dramatic loss of body fat percentage then menstrual periods may stop. That is a sign of a weight that is excessively low and unhealthy. Prolonged amenorrhea can lead to premature osteoporosis and increased risk for fractures. Because there are potentially very serious causes, as well as consequences, of prolonged amenorrhea I recommend that anyone who stops having periods for more than 3 months have it medically evaluated (don’t wait for a year).

      • I would concur with Dr. Seale, and urge you to not ignore prolonged amenorrhea. It’s really important that you are producing enough estrogen for optimal bone development while you are in your teens and twenties and still the opportunity to build bone; you’ll be relying on that base the remainder of your life!

    • OK, I’m going to jump in here, only because this is an area I’m familiar with!

      Emilia, I agree with Dr. Seale on all fronts. I’m going to go ahead and make some assumptions about your amenorrhea, and if I’m wrong, consider it info for everyone, not for you.

      If you have amenorrhea because 1) you have recovered from a bout of disordered eating or significant weight loss, or 2) you went off the pill and it won’t come back, or 3) some combination of these factors, possibly coupled with excessive exercise, then listen up: I feel your pain. I have certainly been through that cycle, as you can imagine, while in recovery, and it can indeed persist after weight gain has reached it’s “healthy” point.

      So what to do? I’m sure you’re being faced with the option either of the pill (which doesn’t feel like a “cure,” especially if you got amenorrhea from going off it) or watchful waiting and patience. By all means, be patient for some time if you want to: I’d say you can even go six months or so if you’re so inclined. Beyond that, though, the risk of bone loss becomes very real indeed, and so you need to start weighing that risk against the imperfections of the pill.

      Listen: I’m no great fan of birth control. I’ve said as much on this blog. But I do think it has an important place in our lives if we want it to (for example, if you are in a place and time in life where you simply cannot have a child), and I think it has a particularly important role when it comes to kickstarting menstrual cycles. It doesn’t always work, but it often does, and you don’t have to take it forever for it to get your body back into balance. That flood of estrogen, meanwhile, prevents bone loss, which is a serious threat to women with amenorrhea. As someone who has had osteopenia from her own ED and subsequent amenorrhea, I can assure you it’s no joke, and that you’ll regret it if you go too long without heeding the damage of low estrogen levels.

      This could be a topic for a whole post, but here’s the upshot: if your amenorrhea is recent, and you just went off the pill, give it some time. Take care of your body, and wait for it to return. If you go quite a long time with no period, though, do consider provera, and if that doesn’t work, consider the pill for 8 months to a year. Is it ideal? No, and it might not even work for you (for example, if your body weight is too low, it won’t do the trick on its own). But it often does work, and moreover, it protects your bones from premature decline. No reason to stay on the stuff for good: simply think of it as a temporary measure you’re taking to protect your body. It carries its own disadvantages, but waiting too long carries greater ones.

      My opinion. If you need to email me, go ahead ๐Ÿ™‚


      • I am glad I read this today. I have stubbornly been avoiding the pill. I was on the pill for 10 years and stopped. Now it has been 1 year and I still have no period. I now have a stress fracture of my left tibia that will not heal (I have been in an aircast for over 6 months). It is discouraging because I want my body to naturally have a period. All my labs have been normal, I am normal weight, I do exercise, but not excessively. I am finishing off my doctoral degree, so I have been brushing it off as stress. I guess I am throwing in the towel. I just hope oral contraceptives will be only a short-term fix to kickstart my menstrual cycle.

  38. Gena and Dr. Seale, thank you so much for this very informative post. Looking forward to seeing a post about Vitamin D next time.

  39. I am so thankful for this post. I am sending this to many people. Thank you!

  40. Hi Dr. Seale,

    Thank you so much for your very helpful post- it really makes sense to my science-based mind. I have one question- is it dangerous to overdose on vitamin b12? I drink 1 cup of Silk PureAlmond everyday (which contains 3 mcg) and have nutritional yeast fortified with B12 (prob 1-2 tbsp) every few days. I don’t want to take a supplement in addition if it could do harm (the amount in the supplement is soooo high!) to my body for taking in too much.

    Thank you!

    • Hello Raychel – provided your vitamin B12 level is currently OK (I like it to be at least 400, and preferably over 600 or 700. There’s no real upper limit that would signify danger), then you’re probably OK with what you’re doing since the RDA for B12 is about 3 mcg per day. The safest thing to do is to get a blood level now, and then depending on where you’re at get it checked in a year to see if you’re holding your own. If so, then keep doing as you are! If not, then it’s time to take a supplement of 50 to 100 mcg per day (it’s safe to take up to 1,000 mcg per day – I haven’t ever seen B-12 toxicity and haven’t seen it reported in the medical literature either).

      • Hi Dr. Seale,

        I am a vegan medical student, and I want to make sure I’m doing things right with my diet… to set the example. ๐Ÿ˜‰ The current recommandations (that I was told in school and on the supplements bottles) is to take one pill (1000 mcg) daily… However, I have heard (from Dr Greger) that it would also be okay to take 2,500 mcg once a week (could it be even less actually?). What would be your opinion on the matter to ensure an adequate B12 intake (with cyanocobalamin)? Thank you very much

  41. Gena, thanks so much for the opportunity to share with your following faithful. I’ve never had a more eloquent or personally moving introduction! Good luck on your test tomorrow – I’m sure it doesn’t stand a chance against you.

  42. Thanks so much Gena!! I like how clear cut this is. I was wondering about taking a supplement (not really a huge medication fan), but this makes perfect sense! And from a fellow biochem major! I can’t wait to get to know Dr. Seale better. One of my big questions, not necessarily vegan-related, is about birth control. I take it for a couple reasons, including its intended purpose, but what kind of hormonal havoc is it wreaking on my body? Are there better options?

    Thanks for sharing the story of how you met Dr. Seale. I’m inspired to talk to someone about my own situation now!

    • Kaitlyn – Essentially, it comes down to a risk versus benefit analysis. There are risks and benefits to everything you do. While there are numerous side effects and potential concerns related to taking hormonal contraceptives (the risk), the fact remains that short of sterilization (I don’t think you probably want to do that), hormonal contraception is the best at preventing pregnancy (the benefit). For the non-hormonal options, they aren’t as effective in preventing pregnancy (the risk), but they also don’t have the associated negative medical side effects (the benefit). Probably the basic question you need to ask yourself is this – what kind of havoc would an unwanted pregnancy wreak at this point in time? The answer will tell you what you need to do.

  43. Great score to get a doc here answering questions! That is, until you are a real doc of course.

    Can the doc explain why raw foodies should not misguidedly think that going to inhale soil or not wash up after the bathroom is NOT a good idea or way to get B-12? Some misguided raw foodies tend to think this when they find out that the reason we need to supplement is that our soils are depleted and our lives so clean.

    • My answer to them would be that while bacteria manufacture B-12 necessary for human health, there is a whole host of bacteria found in nature (including the human intestinal tract), that are not entirely friendly or conducive to good health. Sanitary living has saved millions of lives over the ages, so I wouldn’t be for sacrificing that and going backwards. I’d wash up and take the pill!

  44. Thank you so much for this wonderful, detailed explanation, Dr Seale!

    I take 1000 mg.of sublingual methylcobalamin twice per week, which is as you note, likely more than one likely needs. Though I am not nor have I ever been deficient in B-12 in the 30+ years I have been a vegetarian, I wonder why it is not necessary to take a dose daily, given that B-12 is water not fat soluable. Is it stored regardless?

    • Yes B12 is stored in the liver (mostly) and your stores last you a LONG time (ie: years). Basically the liver is just an extremely efficient organ, so it does not waste what it stores and utilizes what it has sparingly. B12 supplements definitely dont hurt for vegetarians, but if you forget for a day (or week or month or multiple months), you’ll be fine. B12 deficiencies, though they happen (as someone above), are very rare.

    • Karen, Nicole is correct. B-12 is stored in the liver and since we only use a few microgams per day it would take some time for a person with normal liver stores to become depleted, even if they had zero B-12 intake. If a dose of B-12 is forgotten from time to time there’s no concern. However, it’s still a good idea to get into the habit of taking a small dose daily or a larger dose a few times per week. Vitamin B-12 is water soluble, so if your liver becomes “saturated,” so to speak, the excess will just be urinated away.

      • Ahh…I understand now. Thank you so much, Dr Seale (and Nicole) for the clarification for the reasons that that my regime should be sufficient.

        Dr. Seale – Your expertise seems so well aligned well with the experience/needs of Gena’s community. I am really looking forward to hearing your insights on various health issues in the future. This explanation of the intricacies of B-12 was superb.

        Great partnership, Gena!

  45. I love this post!! Thanks for bringing on the science ๐Ÿ™‚ as I study for my Step 2 (booo it’s next week. 9 hours of fun here I come!!!), its nice to see some familiar words. Glad to see this will be a regular thing!

    Good luck on your final!! Gen chem was a pain, orgo I found super fun. If you can do it, I really recommend taking biochem before med school, so once you are in med school is it not so horrific. Wish I had ๐Ÿ™‚

    • Nicole,

      My understanding is that some med schools won’t accept me without bio II, but that many accept biochem as a replacement for bio II. If enough of the schools I’m interested do indeed do that, I plan on taking biochem instead.

      Gen Chem is really a slog sometimes, but everyone tells me I’ll love orgo — in spite of a lot of work.


      • That’s so funny, I thought gen chem was so much better than o-chem. Maybe it depends on if one is a math person? Gena, one reason you might not want to do biochem instead of regular bio 2 is that you’ll need the bio for the mcat, esp the physio that most schools teach near the end (and you def. don’t need biochem for the MCAT). I wonder how biochem will go for me this year. I go to a systems-based med school so biochem is sprinkled in a little at a time, not all in one block.

        • that is definitely true, no biochem on the mcat. if it’s an either/or, definitely go with bio.

          my school is systems-based only in 2nd year so we still have a full block of biochem :/ ugh.

          • Bio it is, then. I should’ve known this plan B was too good to be true! I forget that a lot of my fellow post-baccs were bio majors of some sort, thus have done a lot of this already and can afford biochem and genetics electives.

    • I think what you’re referring to as Step 2 is what we used to call Part 2 back in the dark ages (part 2 national boards) 30+ years ago. I remember them well. Probably better than what I did yesterday…

      • Yup, that’s correct! Coming up in 5 days. Can’t wait… Thankfully then I am done until Step 3.

  46. Thank you so much for this explanation! I recently found out I am B12 deficient and have been taking a liquid supplement, but I was never able to really understand why people generally only get this from animal products. It will be really nice to explain (if I ever have to) the real reason vegetarians like me would be deficient.

    • Dori – keep an eye on that B-12 level so you’re sure that your treatment is effective. Glad this was a help to you and gives you the answers you need to have for others, as well as yourself!

  47. Thanks Gena and Dr. Seale for this informative post.

    I admit, when I saw that molecule picture at the top, my eyes instantly glazed over, I had a bit of a pseduo-panic attack as I was instantly transported back to college and Organic Chem. <–not fun memories for me!

    But it was worth the initial scare to read the Dr's thoughts on B12 and supplementation.

    I have a question for the doctor and millions of other Americans may have this question too…what do you do if you're self employed, have pre-existing conditions, do not qualify for or cannot obtain individual health insurance plans that you purchase on your own, and have exhausted all your resources in order to secure health care coverage.

    What would a doctor suggest the millions of uninsured Americans do? How does he feel this will impact our country financially and from a health standpoint in the future.

    Would love to hear your thoughts, too, Gena on the topic of health insurance and the millions of people without it for whatever the reason.

    • I admit, Averie, that this is a topic I’ve given little thought to, much to my discredit. I just assumed it would become more relevant later in my studies; right now, I’m tackling molecules like that one you shuddered at! I do have people in my life who are well informed on this, so I’ll try to learn more. And I’m sure Dr. Seale has thoughts.

    • Averie and Gena – Wow, this is a question that could be an entire blog (or series of blogs) in and of itself. My first very general comment is that unfortunately America is going down a disastrous medical and financial path of chronic disease care. Unless the trends are reversed through lifestyle behavior change every resource we have will soon be consumed by healthcare. Now to be specific and to try to answer your question – given the circumstances stated, and also assuming good health currently, I would look into getting a high-deductible insurance plan that is HSA (Health Savings Account) approved. The premiums should be more affordable (even with a pre-existing condition), and if you remain currently healthy then you can stay away from the medical system and not need to use the coverage. It becomes more of a “disaster” policy that will save you from bankruptcy if there’s ever a big medical hit you have to take. With the money you save on premiums you can then fund your HSA account with pre-tax dollars, just like a retirement account. I can’t explain all of the nuances of HSA eligible health plans and HSA accounts on this post, but do some research into them – they may be your answer. And also, of course, stay healthy through ideal nutrition (you likely know what that is!), regular exercise, stress reduction, rest, water… :o)

  48. Thank you for this! I just went through 4 weeks of B12 shots (not a big deal at all) and I will now have one a month for 3 months. Then I will be supplimenting orally with sublingual B12. It’s a small price to pay, in my opinion, for all of the other benefits of a vegan diet!

    • You’re 100% correct Wendy – small price to pay. Keep taking your B-12 and you’ll stay a “Healthy Girl”!

  49. Thank you Dr. Seale and Gena for such an informative post on such an important topic!

  50. You say there is really no difference in effectiveness between cyanocobalamin and methylcobalamin. From my understanding and years of nutrition study, instrinsic factor is needed for the body to utilise cyanocobalamin. However, for methylcobalamin, it is in a co-enzyme form that does not require instrinsic factor and is the preferred form of B12 for people who have absorption issues with cyanocobalamin.

    Foods fortified with cyanocobalamin are done so because it is cheaper to produce than methylcobalamin. I recommend to people who need to supplement to take methylcobalamin in a sublingual drop.

    • My understanding is the same – methylcobalamin is most easily absorbed and the the safer bet.

    • Kumara (and also Karen) – from a technical standpoint methylcobalamin is better absorbed than cyanocobalamin, and it is usually the form of B-12 that I choose when buying. However, at the doses that most supplements contain (500 to 1000 mcg), either form of the vitamin will prevent deficiency (the RDA for B-12 is less than 5 mcg). It is also true that intrinsic factor, a gut hormone produced by specific cells in the stomach, is required for B-12 to be absorbed from the small intestine. I didn’t get into this physiology in my post since a lack of intrinsic factor is rather rare in the general population. When intrinsic factor is absent, B-12 may possibly be adequately absorbed by using sublingual lozenges or drops and bypassing the intestinal tract – the doses required are usually at least 1,000 mcg per day, and in that case I would also recommend the methylcobalamin version. However, it may also be necessary to give B-12 injections intramuscularly, initially at frequent intervals until liver stores are replenished, and then monthly on a life-long basis.

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