Michael R Posted February 27, 2015 Report Share Posted February 27, 2015 (edited) All:First: Randy, David: thanks for the comments and questions. Do please note that I had asked: Finally: this is a multi-part article, and unlike posts on the old CR Society email distribution lists, it can be periodically updated thanks to the fine editability of the Forums. To avoid cluttering up the article, please post ask any questions or comments about the contents of this article in a new thread, rather than by hitting "reply" to posts in this one. I will make a good-faith effort to answer such and to update this article as appropriate. So I've opened up this parallel thread to answer your comments and questions. With your permission, I'd like to ask Tim to use his moderator power to delete your originals from the thread that I wanted reserved for the essay itself. Please indicate if this is agreeable.Now: "There are absolutely no natural, plant-based foods that contain vitamin B12."I don't think that this statement is true. Please see:www.ncbi.nlm.nih.gov/pmc/articles/PMC4042564/ First: David, please do me and you and everyone on the Forum a favor: register on the Forums and log in each time before you post! It's fine if you want to use a pseudonym, but registering and logging in will ensure that you can't be impersonated and will make it easier to keep track of your questions, input, and progress. To answer your question: this Japanese group is the most proiminent in recent years to make these claims, measuring B12 levels in nori seaweed and various exotic (to Westerners) mushrooms using HPLC assays which for most things are quite reliable. However, there have been several studies (eg. (1-3)) measuring not just the levels of ostensible B12 in these foods and the blood of people eating them, but to see if doing so actually improves their functional B12 status, as measured by methylmalonic acid levels and similar assays; they have consistently been found not to do so. Thus, either (a) these compounds, too, are inactive corrinoids that happen to bear a very similar HPLC signature to true bioactive B12, or less likely ( B) there really is a small quantity of bioactive B12 in these foods, but its activity is counteracted by the much higher levels of B12-mimicking corrinoids which act as competitive inhibitors for true B12. Either way, there is no way for vegans to sustain B12-dependent metabolic pathways on purely plant-based foods, and vegans need a supplemental source of B12 to avoid dangerous deficiency. Much, much thanks for you efforts in the above.I've wanted to see a comprehensive post on this topic, and your input fits the bill. I'm glad you found it useful. Randy, I had the definite impression that you ate meat; are you vegan, or just curious? Really sad for me to see so little input from all my friends from the prior email list.I hope, at least, they are reading. Remember, the List had gotten pretty darned quiet, aside from postings of Al Pater's source material, for some time; I'd give them time to sort themselves out and start joining the conversation. But I strongly second your call: Old Timers from the List: come on in — the water's fine! References 1: Yamada K, Yamada Y, Fukuda M, Yamada S. Bioavailability of dried asakusanori (Porphyra tenera) as a source of Cobalamin (Vitamin B12). Int J Vitam Nutr Res. 1999 Nov;69(6):412-8. PubMed PMID: 10642899. 2: Dagnelie PC, van Staveren WA, van den Berg H. Vitamin B-12 from algae appears not to be bioavailable. Am J Clin Nutr. 1991 Mar;53(3):695-7. Erratum in: Am J Clin Nutr 1991 Apr;53(4):988. PubMed PMID: 2000824. 3: Schwarz J, Dschietzig T, Schwarz J, Dura A, Nelle E, Watanabe F, Wintgens KF, Reich M, Armbruster FP. The influence of a whole food vegan diet with Nori algae and wild mushrooms on selected blood parameters. Clin Lab. 2014;60(12):2039-50. PubMed PMID: 25651739. Edited February 27, 2015 by Michael R Quote Link to comment Share on other sites More sharing options...
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