Evidence check: B12 in the context of Wechseljahre

Vitamin B12 is essential for energy metabolism, nerve function, and red blood cell formation. During menopause, hormonal shifts and age-related changes in gastric acid secretion can impair B12 absorption, potentially increasing deficiency risk. Symptoms like fatigue, brain fog, and neuropathy overlap with menopausal complaints, making diagnosis tricky. Evidence for routine B12 supplementation in menopause is moderate: treating confirmed deficiency is well-supported, but prophylactic use without testing lacks strong randomized trial data. Women with MTHFR variants (e.g., C677T) or prior gastric surgery are at higher risk. A blood test (holotranscobalamin, homocysteine) before supplementation is advisable. B12 is water-soluble and safe at standard doses, but high-dose therapy should be monitored. Overall evidence grade is 'human-moderate' – observational and mechanistic data are solid, but dedicated menopause-specific RCTs are scarce.