Occurrence of Vitamin B_<12> in Green, Blue, Red, and Black Tea Leaves

Vitamin B_<12> contents of green (0.046-0.263 and 0.125-0.535 μg/100 g dry weight), blue (0.068-0.081 and 0.525-0.528 μg/100 g dry weight), red (0.061 and 0.663 μg/100 g dry weight), and black (0.104-0.859 and 0.305-1.20 μg/100 g dry weight) tea leaves were obtained by intrinsic factor-chemiluminescence and microbiological methods, respectively. Although vitamin B_<12> 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.