What role does B12 play in allergy?

The role of vitamin B12 in allergy is not well established. B12 is crucial for DNA synthesis, nerve function, and red blood cell formation. Some studies suggest immunomodulatory effects: B12 may influence T-cell activity and histamine release. However, findings are inconsistent. Deficiency could impair immune regulation and potentially increase allergic susceptibility, but direct causal evidence is lacking. Evidence comes mainly from observational studies and animal models. In clinical practice, there is no proven recommendation to use B12 for allergy prevention or treatment. B12 testing is only indicated if deficiency is suspected, not as a routine allergy workup. Caveat: High-dose B12 supplementation without medical indication is not advised.