What is vitamin B₁₂? Vitamin B₁₂ (cobalamin) is a water‑soluble vitamin necessary for DNA synthesis, red‑blood‑cell formation and myelin integrity. Deficiency leads to megaloblastic anemia, neuropathy, cognitive decline and symptoms such as fatigue and weight loss ods.od.nih.gov. B₁₂ is naturally present in animal‑based foods (meat, dairy, eggs) and is added to many fortified foods. Adults
