Occurrence of vitamin B12 in green, blue, red, and black tea leaves.

Vitamin B12 contents of green (0.046-0.263 and 0.125-0.535 microg/100 g dry weight), blue (0.068-0.081 and 0.525-0.528 microg/l00 g dry weight), red (0.061 and 0.663 microg/100 g dry weight), and black (0.104-0.859 and 0.305-1.20 microg/100 dry weight) tea leaves were obtained by intrinsic factor-chemiluminescence and microbiological methods, respectively. Although vitamin B12 was found in all tea leaves tested by both assay methods, the higher values by the microbiological method were not due to occurrence of both deoxyribosides and deoxynucleotides (known as an alkali-resistant factor), but may have been due to that of inactive corrinoid compounds for mammals in the tea leaves.