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The B12 Debate
Feb. 22nd, 2005 03:11 pmI just found some more information about vitamin B12. (For those of you just tuning in, my nutrition professor explained that there are no non-animal sources of vitamin B12, causing controversy. I brought it up here, and there was more controversy [sort of])
The only reliable unfortified sources of vitamin B12 are meat, dairy products and eggs. There has been considerable research into possible plant food sources of B12. Fermented soya products, seaweeds and algae have all been proposed as possible sources of B12. However, analysis of fermented soya products, including tempeh, miso, shoyu and tamari, found no significant B12.
Spirulina, an algae available as a dietary supplement in tablet form, and nori, a seaweed, have both appeared to contain significant amounts of B12 after analysis. However, it is thought that this is due to the presence of compounds structurally similar to B12, known as B12 analogues. These cannot be utilised to satisfy dietary needs. Assay methods used to detect B12 are unable to differentiate between B12 and it's analogues, Analysis of possible B12 sources may give false positive results due to the presence of these analogues.
Researchers have suggested that supposed B12 supplements such as spirulina may in fact increase the risk of B12 deficiency disease, as the B12 analogues can compete with B12 and inhibit metabolism.
The current nutritional consensus is that no plant foods can be relied on as a safe source of vitamin B12.
This package of pro-meat propaganda comes from http://www.vegsoc.org/info/b12.html
that is, The Vegetarian Society. I can't find for sure whether "vegetarian source" B12 supplements are for real, or if they are "B12 analogues." The fact sheet goes on to say that Iranian vegans studied were found to obtain adequate B12 through vegetables contaminated with human feces.
The only reliable unfortified sources of vitamin B12 are meat, dairy products and eggs. There has been considerable research into possible plant food sources of B12. Fermented soya products, seaweeds and algae have all been proposed as possible sources of B12. However, analysis of fermented soya products, including tempeh, miso, shoyu and tamari, found no significant B12.
Spirulina, an algae available as a dietary supplement in tablet form, and nori, a seaweed, have both appeared to contain significant amounts of B12 after analysis. However, it is thought that this is due to the presence of compounds structurally similar to B12, known as B12 analogues. These cannot be utilised to satisfy dietary needs. Assay methods used to detect B12 are unable to differentiate between B12 and it's analogues, Analysis of possible B12 sources may give false positive results due to the presence of these analogues.
Researchers have suggested that supposed B12 supplements such as spirulina may in fact increase the risk of B12 deficiency disease, as the B12 analogues can compete with B12 and inhibit metabolism.
The current nutritional consensus is that no plant foods can be relied on as a safe source of vitamin B12.
This package of pro-meat propaganda comes from http://www.vegsoc.org/info/b12.html
that is, The Vegetarian Society. I can't find for sure whether "vegetarian source" B12 supplements are for real, or if they are "B12 analogues." The fact sheet goes on to say that Iranian vegans studied were found to obtain adequate B12 through vegetables contaminated with human feces.
