Caffeine: Friend or Foe?

Can you drink coffee and never feel the effects of caffeine? Or perhaps you are the opposite and feel jittery after just one cup of java. The reasons for that lie in your genetic code. Specifically, in the CYP1A2 gene. CYP1A2 is a gene that encodes a liver enzyme (cytochrome P450 1A2)) involved in caffeine metabolism.

Coffee has a stronger effect on people who have at least one C variant of the CYP1A2 gene (rs762551) than on people who have two copies of the A variant. So if you are A/A at this SNP, you are a fast caffeine metabolizer, meaning that your body can break down and clear the caffeine quickly. However if you are A/C or C/C you are considered a slow caffeine metabolizer and the caffeine lingers in your body for much longer. Several studies have shown that slow metabolizers who ingest two or more cups of coffee (200 mg or more of caffeine) daily are more susceptible to high blood pressure and are at higher risk of heart attacks. Slow caffeine metabolizers should not drink more than one cup of caffeinated coffee (or 100 mg of caffeine) or equivalent caffeine-containing beverages per day. Caffeine is also found in tea, chocolate, soft drinks, energy drinks, and some over-the-counter medications.

While there are other genes that affect caffeine metabolism, CYP1A2 is responsible for more than 95% of the primary metabolism of caffeine. This makes this gene an important part of nutrigenetic testing and complimentary dietary recommendations.