Myths vs facts: CYP1A2 and fertility

CYP1A2 metabolizes caffeine and estrogens. A common myth is that a 'slow' CYP1A2 genotype directly impairs fertility. The evidence is limited and mixed. Some observational studies link high caffeine intake to delayed conception, but the effect is small and not consistently tied to CYP1A2 variants. Mechanistically, caffeine can affect estrogen levels and menstrual cycle, but genotype–phenotype correlations are weak. Fact: Moderate caffeine intake (<200 mg/day) is generally considered safe for fertility. There is no strong evidence that CYP1A2 genotyping improves fertility outcomes. Most professional guidelines do not recommend genetic testing for fertility based on CYP1A2. The evidence level is 'mechanistic' or 'mixed' – plausible biology but insufficient clinical proof. Caveat: Do not overinterpret direct-to-consumer reports; focus on overall diet, lifestyle, and medical evaluation.