Study Finds Genetic Link to Coffee Consumption

The findings suggest your genes may determine your ideal caffeine intake.


Coffee photo by Jamie Ducharme

Do you prefer a dark roast or more of a breakfast blend? Or, perhaps, you’re a latte person? A new study from Harvard School of Public Health (HSPH) and Brigham and Women’s Hospital suggests that your coffee drinking behavior may depend on more than just taste buds and sleep habits—your genes could be playing a part, too.

The study examined the genes of 120,000 habitual coffee drinkers and found six genetic variations that the researchers believe may be related to caffeine’s metabolism and how it affects the consumer. “We pulled together various research teams from around the world, and we worked together to identify a handful of specific and common genetic variants that influence coffee drinking behavior at a population level,” explains the study’s lead author Marilyn Cornelis, a researcher in HSPH’s nutrition department.

In layman’s terms, that means your genes may be the reason you need six cups of coffee to get through the day while your co-worker feels jittery after two, and the reason you’re able to tell if you need another cup or you’ve had enough, Cornelis says.

“Based on these findings, we’re showing that individuals differ in their response and metabolism of caffeine, so the right dose might depend on your genotype,” Cornelis says, noting that the study looked solely at coffee but the findings are likely applicable to other forms of caffeine as well. “Say, for example, one person is consuming four cups of coffee. Their physiological response to coffee might be very different from someone who’s consuming the same amount but has a different genotype.”

The researchers’ next steps will be to determine how to use those findings to produce actionable recommendations for the public. “Since [the genetic variants] have such powerful effects on our actual behavior, the next question will be to see whether they potentially modify the adverse or protective health effects that are linked to coffee or caffeine consumption,” Cornelis says. “It could have implications down the road in terms of health consequences, but we don’t know that yet. These are the stepping stones towards that kind of research.”

Cornelis says further research is important because, as it currently stands, knowledge about caffeine is fairly inconclusive. “The public has been kind of bombarded with a number of different findings regarding coffee and caffeine. We don’t know if it’s good for you or bad for you, and it may vary by your genotype,” she says. “I’m hoping to understand more of the functional rules of these specific variants and see how they potentially modify certain risk factors.”