Evidence check: B12 in the context of allergy

The provided context contains no direct evidence linking vitamin B12 to allergies. Generally, B12 is involved in methylation and immune regulation, and some observational studies suggest a possible link between low B12 levels and increased allergic sensitization. However, the evidence is weak and inconsistent. In practice, B12 deficiency is more commonly associated with fatigue or neurological symptoms, not allergies. Anecdotal reports of allergy improvement after B12 supplementation are not supported by robust clinical trials. Consumer DNA tests may include variants in genes like MTHFR that affect B12 metabolism, but this is not a direct allergy marker. Without specific study data, the connection remains speculative. Safety note: High-dose B12 is generally well tolerated, but supplementation should be medically evaluated if deficiency is suspected.