Role: As part of cobalamin coenzymes, involved in cell synthesis, red blood cell maturation. Regeneration of folate. Maintenance of protective sheath around nerve fibers. Involved in fatty acid metabolism.
Deficiency: Pernicious anemia. Impaired immunity. Diarrhea. Neuropathy, which becomes irreversible. Possible relation to cardiovascular disease from homocysteine build-up.
Sources: Liver and other meats, poultry, fish, and seafood. Milk, cheese, eggs. Only vegetable sources are fortified foods and Cyanobacteria (blue-green algae).
Toxicity: Not determined.