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.
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