Vitamin B12 is synthesized only by certain bacteria and archaea, but not by plants. The synthesized vitamin B12 is transferred and accumulates in animal tissues, which can occur in certain plant and mushroom species through microbial interaction [1-5]. The usual dietary sources of vitamin B12 are animal-source based foods, including meat, milk, eggs, fish, and shellfish, although a few plant-based foods such as certain types of dried lavers (nori) and mushrooms contain substantial and considerable amounts of vitamin B12, respectively. Vitamin B12 is required for the proper function and development of the brain, nerves, blood cells, and many other parts of the body [1-5]. Vitamin B12 deficiency is a common but under-recognized condition which can present with non-specific clinical features and in severe cases with neurological or haematological abnormalities [1-5].