B12 in Plants and Algae Update

I have been catching up on the B12 in plants and algae research.

When I read these papers and see the not-insignificant amount of preparation and analysis that goes into the laboratory methods for trying to measure and accurately describe the B12 in these foods, it seems a lot easier just to feed the foods to humans and see if it improves their B12 status. Instead, we have a never-ending flow of research trying to quantify how much B12 is in various plants which does us almost no good because:

– Even if you find some molecules that seem to be vitamin B12, you don’t know how it will interact with other inactive B12 molecules inevitably also prevalent in these foods.

– We do not know how the B12 got there: whether the plant made it (unlikely), whether it has come from symbiotic bacteria, or whether it came from fecal or insect contamination. Thus, we do not know how reliable it would be in other batches of that food throughout the world.

– The packaging, storage, transportation, and preparation methods can differ greatly between the careful laboratory methods used in these reports and the versions someone might buy in a grocery store.

Nevertheless, this topic is of great interest to much of the vegan community and I will summarize some of the latest papers I’ve come across, though not all are recent.

The Watanabe group, as I refer to them because Fumio Watanabe is often the lead author, is a group of researchers from Japan who regularly publish on these subjects. They published a review of the research in 2013 (1) which was almost an exact duplicate of their review from 2007 (2).

There wasn’t much to report from their 2013 review, but a reader questioned me about one statement they make about B12 being degraded in the presence of both copper and vitamin C. Since many multivitamins contain both copper and vitamin C, is the B12 in these supplements useless? It’s a good question, but the research they base their observation on is, once again, not measuring whether a multivitamin with B12 and copper can improve vitamin B12 status (3). Rather, they took vitamin B12 and added vitamin C and copper to it and then analyzed the B12 to see if it was damaged – a process that significantly differs from eating a multivitamin.

I have not seen research looking at multivitamins and their effects on B12 status, which is a question that needs to be answered even for multivitamins without copper and vitamin C. As a bit of reassurance, I cannot recall any vegans who regularly take a multivitamin with B12 coming down with overt deficiency. That said, it would probably be best for vegans to avoid copper in their multivitamins. I don’t think it warrants throwing out a bottle of multivtiamins, but if you can get a multivitamin without copper, other things being equal, I’d suggest it. I’ll have more on copper absorption in a future post.

The Watanabe group published another paper in 2013, this time testing to see if hydroponically grown lettuce would absorb vitamin B12 if it was injected into the growing medium (4). Indeed, it does, at a rate of .02% to .03%. Enough B12 was absorbed that two lettuce leaves could meet the RDA of 2.4 µg. But it would seem much more efficient to get the B12 directly from fortified foods or supplements rather than running it through hydroponically grown lettuce and losing over 99%.

An Indian research group published an article in 2010 examining the vitamin B12 content of spirulina (Spirulina platensis) (5). They found 35 – 38 µg of methylcobalamin per 100 g of dry mass. Unfortunately, it doesn’t mean much based on the bulleted points above and the fact that other batches of spirulina have not improved vitamin B12 status (see B12 in Tempeh, Seaweeds, Organic Produce, and Other Plant Foods).

Interestingly, the Watanabe group didn’t cite the Indian paper in their 2013 review which included a section on spirulina, so apparently I’m not the only one to hear about these papers years after they’ve been published. 🙂

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1. Watanabe F, Yabuta Y, Tanioka Y, Bito T. Biologically Active Vitamin B12 Compounds in Foods for Preventing Deficiency among Vegetarians and Elderly Subjects. J Agric Food Chem. 2013 Jul 17;61(28):6769-75. | link

2. Watanabe F. Vitamin B12 sources and bioavailability. Exp Biol Med (Maywood). 2007 Nov;232(10):1266-74. | link

3. Takenaka, S.; Sugiyama, S.; Watanabe, F.; Abe, K.; Tamura, Y.; Nakano, Y. Effects of carnosine and anserine on the destruction of vitamin B12 with vitamin C in the presence of copper. Biosci., Biotechnol., Biochem. 1997, 61, 2137-2139. | link

4. Bito T, Ohishi N, Hatanaka Y, Takenaka S, Nishihara E, Yabuta Y, Watanabe F. Production and Characterization of Cyanocobalamin-Enriched Lettuce ( Lactuca sativa L.) Grown Using Hydroponics. J Agric Food Chem. 2013 Apr 12. [Epub ahead of print] | link

5. Kumudha A, Kumar SS, Thakur MS, Ravishankar GA, Sarada R. Purification, identification, and characterization of methylcobalamin from Spirulina platensis. J Agric Food Chem. 2010 Sep 22;58(18):9925-30. | link

15 Responses to “B12 in Plants and Algae Update”

  1. Jan Says:

    I don’t get it but some vegans tend to be very reluctant to take supplements.

  2. ed Says:

    Thanks for keeping us readers up to date!

    “That said, it would probably be best for vegans to avoid copper in their multivitamins. I don’t think it warrants throwing out a bottle of multivtiamins, but if you can get a multivitamin without copper, other things being equal, I’d suggest it. I’ll have more on copper absorption in a future post.”

    Or, as I do, keep taking a separate B12 supplement.

    From a practical vegan perspective I think any text of this kind should end with a big, bold flashing text: if become vegan, take a B12 supplement from the start.

    In a more long term perspective, I wonder if the vegan community should try to push for more B12 fortification in foods. Most vegan milks that I’ve come across have only small amounts of B12. The carton in my fridge right now contains 15% of recommended daily B12 intake in 1 decilitre of milk. I would need to drink three quarters of the one litre carton to get the daily intake from that source. Why not go for higher concentrations in the fortification?

  3. Dan Says:

    Hi Jack, I was wondering if you could help settle something for me.

    According to my dietary analysis, on a day when I regularly consume all three meals (which is not every day, mind you), I am getting 736 RAE of vitamin A (somewhat below the 900 RAE recommended daily intake for this fat-soluble vitamin).

    I’ve done some research on supplementation, as some high-vitamin A plant foods tend to be high in carbs (butternut squash, carrot juice, carrots), and I am already consuming >130 g of carbs per day, and have a tendency toward metabolic syndrome. What I found is somewhat worrisome:

    -in a randomized trial of nearly 30,000 Finnish male smokers, beta carotene supplementation (20 mg/d) increased the risk of stomach cancer, prostate cancer and lung cancer. After the trial ended and supplements were stopped, there was still an increased risk of death, largely due to cardiovascular disease, 5-7 years post-intervention. Now one can say “how does this result generalize to vegan non-smokers”, but I think I would always give the benefit of the doubt and say “why are Finnish male smokers who do not take beta carotene at lower risk for these diseases than Finnish male smokers who do take beta carotene?”. Clearly in this trial the only thing that changed was the beta carotene intake (there was a separate arm with alpha-tocopherol, but i won’t summarize it here)

    -second, a number of cohort studies suggest that both men and women with high vitamin A intake have high rates of hip fracture and osteoporosis; one study suggested the best intake level was between 0.6 mg and 0.9 mg per day of beta carotene. The risk does not seem to be limited to pre-formed vitamin A in meat and eggs, but also the indirect source of plant-based beta carotene. The association has been verified in animal models.

    -third, vitamin A deficiency appears to be somewhat rare in developed countries like the US and Canada, and largely limited to people with mental disorders or autism as well as those with primary biliary cirrhosis and other liver problems preventing absorption of fat-soluble vitamins.

    -fourth, 4-5 trials of vitamin A for cardiovascular prevention were all neutral. Three antioxidant trials in smokers found increased risk of lung cancer.

    Would the best way to go be to just increase green leafy vegetables? Thanks.


  4. Jack Norris RD Says:


    I would recommend against supplements with vitamin A or large amounts of beta-carotene. Leafy greens sounds like a great plan.


  5. Dan Says:

    Thanks Jack. That is most helpful.


  6. Andreas Says:


    Soil contaminated with glutamic acid or Auxigro(contains glutamic acid) will yield B12 in the soil by microorganisms. Naturally, other than feces, I doubt there is a lot of B12 in soils untouched by man because of the way microorganisms produce the vitamin. If soil/plants was a good source of B12, we and all other animals wouldn’t have specific mechanisms to produce our own.

    Its rather impossible than unlikely that plants produce B12 since they have no enzymes to do so and no use for B12 since they lack a nervous system.

    As for the 2013 paper, its insanity. I keep seeing experts doing the same thing over and over and expecting different results. Manipulating foods so they absorb more B12 isn’t the answer; understanding the science is. It’s unfortunate that the majority of experts aren’t really experts.



  7. Dan Says:

    I would question why anyone would want to see if hydroponically grown lettuce would take up B12. It is quite simple to take a supplement or consume a fortified food. Hydroponically grown lettuce must be exorbitantly expensive even without B12 pre-treatment. I agree with you that it would be much easier to demonstrate whether humans who eat these experimental food items demonstrate increasing B12 levels.
    Andreas, regarding that article, I briefly read the abstract. I often see these sorts of reviews following negative results from randomized trials. Human beings have the sort of imagination to postulate virtually any explanation for bad results in a clinical trial – wrong dose, wrong patient population, wrong formulation (cis vs trans), lack of a methyl group, etc, etc. Maybe that is not being done here (hard to tell from the abstract), but any hypothesis that a different form of beta-carotene might be beneficial must be tested in a separate randomized trial. I just don’t see that happening. As to lutein, etc, same problems with lung cancer recently came up in the AREDS-2 study in JAMA for macular degeneration. I think I will go get some dandelion leaves.

  8. Dan Says:

    I wonder if it is worth having a section on potassium on the vegan nutrition website? There are alot of data to suggest that diets high in potassium help to lower blood pressure and stroke risk. Many people are on diuretics that leach potassium into the urine. Caffeine and alcohol also have this effect. I didn’t see K+ listed among the nutrients that were discussed there – but is it even relevant to vegan health? I noticed my own intake is suboptimal compared to the recommended daily intake – likely because I don’t take much fruit in my diet. If vegans tend to eat a lot of fruit my guess is they will have no problems with potassium or even need a supplement. People on BP drugs may run into problems with either low potassium (diuretics) or high potassium (K-sparing diuretics, ACE inhibitors, angiotensin blockers). Both low and high potassium levels are bad, obviously.

  9. Andreas Says:

    “I would question why anyone would want to see if hydroponically grown lettuce would take up B12.”

    Same here. From my observations of people; people want to come up with solutions however its unfortunate that they have been taught that it is okay to manipulate things to come up with solutions. Or maybe its greed or delusion or a combination of all the above.

    “I agree with you that it would be much easier to demonstrate whether humans who eat these experimental food items demonstrate increasing B12 levels.”

    Where did I imply this?

    I was referring to the use of synthetic vitamins in those trials. Regarding synthetic vitamins; my understanding is that synthetic vitamins are produced from petroleum and other non biological matter.

    Dandelion greens for lutein. Nice!

  10. Jack Norris RD Says:

    > “I agree with you that it would be much easier to demonstrate whether humans who eat these experimental food items demonstrate increasing B12 levels.”

    > Where did I imply this?

    I think Dan was talking to me. However, I do not mean they should test to see whether B12 levels have increased, but rather they should test to see if MMA levels have decreased. They should probably do both.

  11. Dan Says:

    Andreas, you posted the following interest links, which I read:


    I am not sure I agree with everything posted on the internet.

    The authors seem to suggest ‘inside knowledge’ of why certain supplement trials failed, which they blame on provision of mega doses of highly synthetic isolated micronutrients.

    Certainly this information is concerning to me as I take a couple synthetics (namely B100 complex and vitamin D). However, this is the first I have heard of this problem. It would be nice to see some proof – comparing whole food nutrients to synthetic vitamins – e.g. for a problem like B12 deficiency – but I don’t think we’ll ever see a randomized trial.

    Is it worth purchasing expensive whole food derived nutrients like B complex? I take it because I got angular stomatitis and avoid grain. It cleared up the problem within 48 hours. Thus it seemed to improve a general mucosal healing defect. Whole food derived nutrients are far more expensive.

    Just because something originally derives (is isolated from) coal tar does not mean it is actually coal tar. Just because something comes from a natural plant does not mean it is safe to eat (ricin in castor beans, digitalis glycosides in foxglove and oleander, etc). This article makes alot of aspersions that are non-scientific in nature.

    I would avoid taking alot of supplemental vitamin A, beta carotene, folic acid, vitamin E, or magnesium – because randomized trials have conclusively demonstrated harms from doing this.

  12. Dan Says:

    Well, I finally made the transition to full veganism. Took me over a year to get my act together. No more dairy was the hardest part. But a shake for breakfast, salad for lunch, soup for dinner really does the trick. Not claiming my diet is optimally healthy – it is low in vit A, B12, D, iodine – but it is probably least cruel ethically speaking. Thanks Jack for your comments on dairy in an older thread. I simply had no idea what was involved in the dairy business. Very eye-opening.

  13. Andreas Says:

    Congrats Dan.

    If you feel fine with the synthetic vitamins, follow your own truth. I would share how you can make extra B vitamins with bacteria but than I would have to share how B12 is made. You’ll have to keep supplementing with the B vitamins for the time being.

    How are you having a problem with Vitamin A?

  14. Dan Says:


    Vitamin A deficit in the diet – getting only about 700 IU per day, whereas I believe the recommended intake is on the order of 900 IU per day. Not sure how concerned to be about this 200 IU deficit, as my night vision is fine and chelitis has long since gone away.

    How do I make extra B vitamins with bacteria?

  15. Andreas Says:


    “How do I make extra B vitamins with bacteria?”

    If you were in my shoes, would you actually share the information on a blog?

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