Vitamin B12 (Cobalamin) for Mood Support

Research suggests a complex and somewhat inconsistent picture regarding vitamin B12 and mood support. A 2006 narrative review proposed that B12 deficiency may contribute to mood disorders through its role in homocysteine metabolism and gene regulation, and noted potential protective effects against psychiatric conditions, but a more rigorous 2024 systematic review and meta-analysis pooling data from nine randomized controlled trials found no statistically significant effect of B12 supplementation on depressive symptoms in the general population, with effect sizes close to zero. Studies indicate that the evidence base leans toward neutral to unsupportive when it comes to supplementation improving mood outcomes directly, though researchers in the 2024 meta-analysis acknowledged that people with confirmed B12 deficiency — a group shown to be surprisingly common in some populations, such as vegetarians and younger urban adults in observational data — may respond differently and warrant further investigation. Overall, the available research does not currently support broad use of B12 supplementation for mood in the absence of a documented deficiency, and the strongest findings come with notable limitations, including reliance on small samples, heterogeneous study designs, and populations that may not have had deficiency at baseline.