Vitamin B12 supplementation: when it helps and when it doesn’t

Vitamin B12, also known as cobalamin, is essential for red‑blood‑cell formation, nerve function and DNA synthesis. The adult daily requirement is about 2.4 µg, which must be obtained from food because the body cannot produce it. Deficiency develops slowly, often over months or years, and can cause persistent fatigue, concentration problems, reduced performance, pallor, loss of appetite, and neurological symptoms such as tingling in the hands and feet, gait instability, muscle weakness, depression or irritability. At risk groups include vegans, older adults and people with certain medical conditions. While the liver can store B12 for years, supplementation is not always necessary; unnecessary use may not provide added benefit. Untreated severe deficiency can lead to lasting neurological damage.