Biologically Active Vitamin B12 from Edible Seaweeds

Vitamin B₁₂ has the largest molecular mass and the most complex structure among all vitamins. Vitamin B₁₂ functions as coenzymes of methionine synthase and methylmalonyl-CoA mutase involved in methionine biosynthesis and in amino acid and fatty acid metabolism, respectively, in humans. Vitamin B₁₂ is synthesized by certain bacteria and archaea only and not by the majority of plants. Animal-based, but not plant-based, foods are considered to be a major dietary B₁₂ source. Thus, strict vegetarians or vegans who do not consume any animal-based foods are reportedly at a greater risk of developing vitamin B₁₂ deficiency. The major symptoms of vitamin B₁₂ deficiency include megaloblastic anemia and neuropathy. Although vitamin B₁₂ is generally absent in plant-derived foods, we have identified edible seaweeds that naturally contain large vitamin B₁₂ amounts. Porphyra spp. contain substantial vitamin B₁₂ amounts, whereas other edible seaweeds contain none or only trace amounts. This chapter describes the characterization of vitamin B₁₂ from edible seaweeds.