Biologically Active Vitamin B12 Compounds in Foods for Preventing Deficiency among Vegetarians and Elderly Subjects
2013
Watanabe, Fumio | Yabuta, Yukinori | Tanioka, Yuri | Bito, Tomohiro
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. Unexpectedly, detailed characterization of vitamin B₁₂ compounds in foods reveals the presence of various corrinoids that are inactive in humans. The majority of edible blue-green algae (cyanobacteria) and certain edible shellfish predominately contain an inactive corrinoid known as pseudovitamin B₁₂. Various factors affect the bioactivity of vitamin B₁₂ in foods. For example, vitamin B₁₂ is partially degraded and loses its biological activity during cooking and storage of foods. The intrinsic factor-mediated gastrointestinal absorption system in humans has evolved to selectively absorb active vitamin B₁₂ from naturally occurring vitamin B₁₂ compounds, including its degradation products and inactive corrinoids that are present in daily meal foods. The objective of this review is to present up-to-date information on various factors that can affect the bioactivity of vitamin B₁₂ in foods. To prevent vitamin B₁₂ deficiency in high-risk populations such as vegetarians and elderly subjects, it is necessary to identify plant-source foods that contain high levels of bioactive vitamin B₁₂ and, in conjunction, to prepare the use of crystalline vitamin B₁₂-fortified foods.
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