Vitamin B12: Importance, absorption, and dietary requirements

Vitamin B12, or cobalamin, is essential for blood formation, DNA synthesis, energy metabolism, and the maintenance of the nervous system. While it is found primarily in animal products like meat, fish, eggs, and dairy, deficiencies can occur even in individuals with adequate dietary intake due to absorption issues.

Effective absorption requires stomach acid, pepsin, and the intrinsic factor produced in the gastric mucosa to facilitate transport to the small intestine. Factors that can impair this process include gastric surgery, autoimmune gastritis, Helicobacter pylori infections, and certain medications. Because the body maintains large liver stores, a deficiency may develop slowly and remain asymptomatic for a long period, often manifesting as fatigue, concentration problems, or tingling sensations in the extremities.

Daily requirements vary by age and life stage. According to the German Nutrition Society (DGE), the standard requirement for adults is 4.0 µg, though this increases during pregnancy (4.5 µg) and breastfeeding (5.5 µg). Specific lifestyle factors, such as alcohol consumption or the use of oral contraceptives, may also influence individual nutritional needs.