A reader asked about a study on Korean centenarians getting B12 from fermented foods, so I did a write-up on fermented foods in general and that study in particular and placed it in B12 in Tempeh, Seaweeds, Organic Produce, and Other Plant Foods on VeganHealth.org.
It is reproduced here:
Because bacteria produce vitamin B12 and fermented foods are generally fermented using bacteria, there are many rumors regarding vitamin B12 being in fermented foods. To my knowledge, no vitamin B12-producing bacteria is required for any fermented food and, therefore, any fermented food that contains vitamin B12 does so via contamination. Because the human colon contains vitamin B12-producing bacteria, it is possible for B12-producing bacterial contamination to occur during food preparation, particularly in places that do not have high levels of cleanliness. To my knowledge, no fermented plant food in Western countries has been found to contain relevant amounts of vitamin B12 analogues.
[snip - nothing new, but click here if interested.]
A 2010 paper from Korea (1) showed that Korean centenarians (people who live to be 100 years old) who ate only small amounts of animal products had normal vitamin B12 levels. The researchers measured the B12 content of plant foods using a biological assay and found many of the fermented foods and seaweeds to contain vitamin B12 analogues, which they considered to be active. They determined that the centenarians were getting about 30% of their B12 from plant foods and that it was a physiologically important amount.
This could be the case, especially given that the subjects ate fermented foods at almost every meal, much of which is homemade kimchi that, according to the researchers, is fermented for at least 10 months.
While this study is very interesting, unless kimchi produced in western countries is reliably shown to lower MMA levels, it would not be wise to rely on it as a significant source of vitamin B12.
1. Kwak CS, Lee MS, Oh SI, Park SC. Discovery of novel sources of vitamin b(12) in traditional korean foods from nutritional surveys of centenarians. Curr Gerontol Geriatr Res. 2010;2010:374897. doi: 10.1155/2010/374897. Epub 2011 Mar 8. | link