Caffeine metabolism speed

How fast caffeine leaves your system depends on the CYP1A2 enzyme that breaks it down plus AHR, which controls how much of that enzyme you make. The two genes point the same direction, so reading them together gives a steadier read than either alone.

Possible results

Fast caffeine metabolism. You carry the fast, highly inducible version of CYP1A2 plus an AHR variant that helps ramp that enzyme up, so you tend to clear caffeine quickly. Coffee's kick may feel shorter and a later cup is less likely to disturb your sleep, though smoking and some medications speed this up further. Treat this as a tendency, since the evidence is soft.

Slow caffeine metabolism. You carry little of the fast CYP1A2 activity and little of the AHR induction signal, so you likely break caffeine down on the slower side and it can linger for hours. An afternoon coffee may disturb your sleep or leave you jittery more than it would for a fast metabolizer, so keeping caffeine earlier in the day tends to help.

Intermediate caffeine metabolism. Your CYP1A2 and AHR variants put you in the middle for caffeine clearance, neither clearly fast nor slow. How caffeine affects you will depend a lot on dose, timing, sleep and habit, and these genes are only a gentle hint.

Evidence & sources

This panel reads CYP1A2*1F, AHR.

Combines CYP1A2 and AHR. This is softer evidence than pharmacogenes like CYP2C9, and smoking and several medications strongly speed up caffeine clearance regardless of genotype.

Related

Adult lactose digestion · Alcohol response (flushing & dependence risk) · HDL cholesterol · Omega-3/6 conversion efficiency · Sweet tooth / carbohydrate preference (FGF21) · Triglycerides · Vitamin D status (low-D genetic burden)