Reactions to coffee seem strangely individual. Some people can drink it after dinner and go straight to sleep, while others have one cup in the morning and feel jittery, sweaty, or get heart palpitations. What gives? Meet your caffeine gene. It’s called CYP1A2 because it controls the enzyme CYP1A2, and its this enzyme that determines how you metabolize caffeine: fast, meaning you tolerate it well and it leaves your system quickly, or slow, meaning your body doesn’t get rid of it efficiently, so you feel its effects harder and longer.
We inherit two copies of the caffeine gene, one from mom and one from dad. If you have the fast variant, your liver breaks down caffeine quickly and efficiently. If you have two of the fast variants, you handle coffee (and tea and even energy drinks) like a boss, breaking down caffeine four times faster than those who have one or two of the slow variants of this gene. Are you one of the lucky ones? Here’s the breakdown:
40 percent of people are fast metabolizers, with two copies of the fast variant.
45 percent have one slow and one fast copy, so they are middle-of-the-road caffeine metabolizers.
15 percent carry two copies of the slow variant and are slow metabolizers.