Can B12 help with allergy?

Whether vitamin B12 can help with allergies is not clearly supported by evidence. Mechanistic studies suggest B12 is involved in homocysteine metabolism and DNA methylation, which may influence immune regulation. Some observational data link low B12 levels with higher allergy prevalence, but no robust clinical trials show that B12 supplementation reduces allergic symptoms. The evidence is weak and mechanistic, not clinical. Consumer tests like MyBody-X may measure B12 status, but they are not diagnostic or therapeutic for allergies. If you suspect a deficiency or have allergy symptoms, consult a doctor. A balanced diet is the best approach; B12 supplements are not recommended for allergy treatment without a proven deficiency.