How does your body react to caffeine? Genetics can help tell the story

Caffeine sensitivity

Caffeine fuels the world, rousing millions from bed every morning and keeping them going into the night. It wakes us up, makes us productive (maybe even giddy), and some research says it might even be good for your heart. It can be hard to imagine living without it—but for certain individuals, caffeine can lead to jitters and anxiety. What’s more, some studies suggest it’s actually not all that great for everyone.
Why the contradiction? The answers might lie in genetics.
People who metabolize caffeine quickly are less sensitive to it than those who take longer. Fast metabolizers might not feel anything at all (called hyposensitivity), while slow metabolizers could feel jittery after drinking the same amount (hypersensitivity). These two extremes are determined by variants of the CYP1A2 gene, which codes for an enzyme that breaks down caffeine. Approximately 45% of people fall in the category of a fast metabolizer because they inherited two copies of the CYP1A2 gene variant, one from each parent.
Testing can be helpful if you suspect you’re sensitive to caffeine—especially if you have other conditions that could make that sensitivity more serious. Remember that caffeine sensitivity is influenced by genetics; it isn’t the same as caffeine tolerance, which is a decreased response to caffeine from regular use. With expert genetic analysis and consultation with health professionals, you can find out whether switching to decaf might be a healthy move.
This is important because a study funded by the National Institutes of Health found that caffeine can be tied to an increased risk of heart attacks—but only in slow metabolizers. The study’s authors believe it’s because caffeine lingers in the slow metabolizers longer, giving it more time to act as a heart attack trigger. The same study also found that coffee can actually protect the hearts of fast metabolizers. They’re less vulnerable to the unwanted effects of caffeine because they break it down faster, but they still get the antioxidants, polyphenols, and other compounds found in coffee believed to promote good health. So for coffee drinkers who might have certain heart conditions, it may be worth finding out whether they’ve inherited the slow metabolism variant.
But CYP1A2 isn’t the only gene involved in caffeine metabolism; in fact, a number of genetic variants have been linked to caffeine habits. And more broadly, the relationship between genetics, nutrition, and overall health is exceptionally complex. Still, genetic tests can help you gain insight, even if just a small amount, into the inner workings of your body.

Citation: Coffee and Caffeine Genetics Consortium et al. “Genome-Wide Meta-Analysis Identifies Six Novel Loci Associated with Habitual Coffee Consumption.” Molecular psychiatry 20.5 (2015): 647–656. PMC. Web. 31 Aug. 2017.

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