What to watch with Folsäure and fertility?

Folic acid (vitamin B9) is critical for fertility and a healthy pregnancy, primarily to prevent neural tube defects in the developing embryo. Women planning pregnancy are advised to supplement with 400–800 µg folic acid daily. Genetic variants such as MTHFR C677T (rs1801133) can impair the conversion of folic acid to its active form (5-MTHF). Carriers of this variant (about 30–40% of Europeans) may have slightly elevated homocysteine levels, which have been linked to fertility issues. However, the evidence is mixed: some studies associate MTHFR variants with recurrent miscarriage, while others find no significant effect. Importantly, a DNA test alone does not replace blood testing. Before switching to methylfolate (the active form), homocysteine levels should be measured. Also, high-dose folic acid (>1 mg) can mask vitamin B12 deficiency. For men, folic acid may also influence sperm quality. Bottom line: folic acid is evidence-based and essential, but genetic testing provides only a hint – clinical relevance is often small. Consult a doctor or dietitian when planning pregnancy.