Vitamin B12 26

by Jack Norris, RD

For the last few months, I was feeling sluggish, had to lie down a couple of times a day, found it difficult to work evenings and to exercise for long periods. Under [an] MD’s guidance, I was taking protein powder, creatine, testosterone, nystatin, etc., all to no avail. I was taking nutritional yeast every day, so I knew it wasn’t B12 deficiency. Then, one day, I came across your B12 article by sheer accident. I wasn’t going to read the whole thing, but I glanced through it and was struck by your insistence that none of the usual sources are adequate. I still didn’t believe it, but I had some old B12 pills in the fridge, so I popped one. The effect was almost immediate and remarkable. I have been taking them almost every day, my stamina and energy level are up, and I feel middle-aged again instead of a tired old man.

–Alex Hershaft, PhD, President of Farm Animal Rights Movement

Vitamin B12 is a complicated vitamin with a unique absorption mechanism and a number of inactive analogues—molecules that appear to be active B12, but actually are not—that possibly interfere with its function.

Vitamin B12 is generally found in all animal foods except honey. But there is no reliable B12 in Plant Foods, including tempeh, seaweeds, and organic produce. Luckily, vitamin B12 is made by bacteria and doesn’t need to be obtained from animal products.

It’s fairly easy for most vegans to obtain a source of vitamin B12, and taking B12 on a regular basis will provide you with a B12 status equal to or superior to people who rely on animal products for B12. But what if you don’t bother?

One of the earliest studies conducted on vegans, from the U.K. in 1955, found significant vitamin B12 deficiency with some suffering from nerve damage and dementia. This and many other Individual Cases of B12 Deficiency in Vegans, and a great deal of other research, has led to the overwhelming consensus in the mainstream nutrition community and vegan health professionals that vitamin B12 fortified foods or supplements are necessary for the optimal health of vegans.

Despite the overwhelming evidence, some vegan advocates still believe that “plant foods provide all the nutrients necessary for optimal health,” and don’t address vitamin B12 when promoting the vegan diet. Others emphasize that humans need only small amounts of B12 and that it can be stored in the body for years, implying that there’s nothing with which to concern ourselves.

While it’s true that at the time many people become vegan, they have enough B12 stored in their livers to prevent overt B12 deficiency for many years, markers of B12 deficiency usually start to increase abnormally within a few months.

Overt B12 Deficiency

B12 protects the nervous system and without it permanent damage can result (e.g., blindness, deafness, dementia). Fatigue and tingling in the hands or feet are often the early signs.

Vitamin B12, like folate (aka folic acid), is needed to help red blood cells divide. In some cases, vegans may get so much folate that even with B12 deficiency, their blood cells continue to divide properly. But in other cases, a vitamin B12-deficient vegans’ blood cells will fail to divide properly and they’ll become fatigued due to macrocytic anemia, also known as aka megaloblastic anemia anemia.

Mild B12 Deficiency

Homocysteine is a byproduct of protein metabolism that the body clears with the help of vitamin B12. Elevated homocysteine levels are linked with increased risks of dementia, heart disease, and stroke.

From 1999 to 2003, many studies found that vegans who weren’t supplementing with vitamin B12 had unusually high levels of homocysteine. In contrast, one study found that vegans who supplement with vitamin B12 (an average of 5.6 mcg/day) had homocysteine levels well within the healthy range.

What Vegans Need to Know

The most critical information to know is:

For more opinions, see this open letter from health professionals and vegan organizations:

What Every Vegan Should Know about Vitamin B12

Vitamin B12—Are You Getting It?

This article provides a thorough review of the scientific literature on vitamin B12 and the vegan diet—it includes every important study on vegans published since 1980.

The B12 Molecule

Measuring B12 Status


Plant and Intestinal Sources

Vitamin B12 Supplements

B12 Status of Vegans

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  • If you have a question about whether it's okay to cut supplements in half or combine supplements to achieve the dose we recommend, the answer is “Yes.” Be aware that nutrient recommendations are only estimates—it's not necessary to consume the exact amount we recommend every single day.
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26 thoughts on “Vitamin B12

  • Meredith

    I recently found a B-Complex product that appears to be sourced from quinoa sprouts. The product includes B-12, but I’m concerned that this may be an inactive analogue unless they are just using the quinoa as a medium for bacteria-derived B-12. The product is produced by Swanson, and when I look at the Supplement Facts on the back, each vitamin lists next to it in parentheses “PANMOL(r) B-COMPLEX from quinoa sprouts.”

    There’s very little information on the PANMOL site, and the research section does not list any actual research. I’m guessing they sell directly to supplement manufacturers, but this is unclear as well. They’re an Austrian company, but it looks like they partner with a company in the USA called Stauber. The Swanson product I bought is vegan, but it looks like the Stauber product may not be, but that’s neither here nor there since I’m just looking for info about the PANMOL itself. The Stauber site claims that all of the B vitamins are in their active forms.

    I’m having a hell of a time trying to find actual research on this. Do you think this is a B-12 analogue or actual biologically-active B-12. I’m concerned that I may have purchased an ineffective product. My Google searches have found nothing on B-12 from quinoa sprouts either. Thanks for your help!

      • Meredith

        Thanks! I managed to track down the FDA GRAS Notification for PANMOL. It just says “cobalamine” in the document but not which kind, so I will be looking for a different supplement.

    • Taylor Wolfram

      We looked into duckweed and determined it is much too soon to conclude that it is a reliable source of vitamin B12 for humans.

  • Joel Marks

    What’s with the new study about high B12 intake and hip fractures (in older women)? I am in particular taken aback by the extreme discrepancy between what the study labels high intake (20 mcg of B12) and the daily dosage of supplement I take (500 mcg).– an older man

    • Taylor Wolfram

      Given that the findings from this study on B12 and hip fractures are statistically weak, that they’re based on an observational study (which only shows correlations), and go against research showing a beneficial effect of higher B12 levels on bones, we don’t think this evidence is enough to justify changing our recommendations. While we generally recommend 500 µg/day for people over 65 (because of the research explained here), if you get your B12 levels tested regularly and they’re within the normal range, it would appear safe to follow the recommendations for people under 65.

  • Norma C Morales Sandoval

    I am vegan because I care for nonhuman animals who are mistreated by humans. Their lives are worth the same, if not more that humans, therefore I won’t take anything that comes from them. It is just not ethical. I already have lots of benefits from being vegan: lots of energy; strong immune system, I do not get cold or flu even if I am exposed to it or I’ll get immunity by having a sub clinical illness which gives me immunity against that specific strain; if I get a cut or another injury, I heal fast. Another benefit I get is my risks for cancer and cardiovascular disease are reduced.

    Since animals make vitamin B12 in their system, is there an specific microbial source that can strengthen my own bacteria producing B12?

    • Taylor Wolfram

      Hi Norma, the place in our intestines where bacteria make vitamin B12 is lower down than where we absorb it. Which means that we do not absorb vitamin B12 made by the bacteria in our intestines. The only reliable vegan sources of vitamin B12 are fortified foods and supplements.

  • Deeddee

    A vegan mom since pregnancy is low on breastmilk and feeding her 5 mos old a vegan formula . This homemade formula is Almond milk , spirulina, nutritional brewers yeast, sacha,powders, coconut oil are main ingredients . Can an baby aborsorb vita b 12 from such a mix?

    • Reed Mangels

      Please see the Pregnancy, Infants, and Children section of our website for more information and resources for vegan infants. Specifically, this section says:
      Vegan parents should not try to make their own infant formulas as this often leads to poor child development. Although more research is desirable, it appears that soy infant formulas are safe. See below for information regarding soy formulas.”
      In addition to real concerns about vitamin B12 from the formula you describe, calories, protein, calcium, iron, zinc and many other nutrients could be too low or too high. Please, for the sake of this infant’s health and well-being, strongly encourage this mom to change her plans. Some suggestions:
      • consult a certified lactation specialist to address breastfeeding issues
      • use a commercial soy formula in place of the homemade formula
      • consult with a registered dietitian to discuss feeding vegan infants and children.

  • Doug

    Is there any reason to avoid the cyano form when breastfeeding infants, in case maybe it could burden their young liver, or any other reason?

  • Aileen

    Hi. I am obese and trying to eat healthier. Went on a 10 day whole plant based diet through a work-wide health challenge and while I don’t envision adopting this diet for life, I would like to try and use the recipes I like and try to avoid dairy and oil while limiting meat consumption to poultry now and then. I started taking B12 with the challenge (I’m on day 15). I had no idea what to buy. My bottle says 3000 mcg and directions say to take one daily. Please let me know if this is too much. Also, I am diabetic, on medications, and have blood work taken evey 6-8 months. My doctor has never said anything about my vitamin B12. He did put me on vtiamin D3, 2000 units, daily. I would appreciate your advice. Would you please email your response as I found this website while scrolling and not sure I’ll get back! Thank you very much.

  • Belen

    Hi I’m having much acne since I’m taking cyanocobalamin pills. I have stopped taking them as a temporary measure. I am vegan and I don’t know what I should do in the long term. Any advice? I’m quite worried. Thank you in advance!

  • Marcus

    What’s your opinion regarding taking B12 individually or as part of a “B complex” ie. with several B-vitamins? Does the latter increase absorption?

    • JackNorrisRD


      I took that page down when I migrated everything to the new site because it was so outdated and due to the fact that spurious correlations between disease and high B12 levels are too burdensome to track just to say we did it. If any research comes out that seriously implicates high B12 intakes as a cause of disease, we’ll cover it on our updates blog which you can sign up for at the bottom of each page on the website.

  • Bernadette Spencer

    Lots of information and still looking for a clear answer.. Do we need! B12 supplements as vegan, vegetarian or meat eater?