What to watch with CYP1A2 and fertility?

CYP1A2 is a phase I enzyme involved in metabolizing caffeine and estrogens. Some research suggests that slow vs. fast CYP1A2 activity could influence hormone clearance and thus fertility. However, the evidence is weak: no robust clinical trials directly link CYP1A2 genotypes to fertility outcomes. Most data come from observational or mechanistic studies. Moreover, caffeine metabolism is strongly modulated by lifestyle factors (smoking, medications, diet). A genetic test alone is therefore not clinically useful for fertility guidance. It is more sensible to moderate caffeine intake (≤200–300 mg/day when trying to conceive) and adopt a holistic lifestyle approach. Direct-to-consumer tests claiming personalized fertility diets based on CYP1A2 are not evidence-based. Evidence: mechanistic/unclear.