How are Folsäure and Allergie related?

The relationship between folic acid (vitamin B9) and allergies is not clearly established in science. Folic acid is involved in one‑carbon metabolism and can influence epigenetic processes that regulate the immune system. Some observational studies suggest that high folic acid intake during pregnancy may slightly increase the risk of allergic diseases like asthma or eczema in offspring. Other studies found no effect or even a protective association. However, randomized controlled trials demonstrating a causal link are largely lacking. It also remains unclear whether synthetic folic acid from supplements differs from natural dietary folate. For individuals with genetic variants affecting folate metabolism (e.g., MTHFR), there are no specific allergy recommendations. Overall, the evidence is mixed and based mainly on observational data. A direct benefit of folic acid supplementation for allergy prevention or treatment is not proven. In case of existing allergies, folic acid intake should be part of a balanced diet without excessive supplementation.