Tea or Coffee? Study Suggests Genes Influence Which Drink We Prefer 

The battle for beverage supremacy between tea and coffee drinkers really centers around one big question: How could someone possibly prefer one over the other? The answer to this question is definitely a matter of taste — though a study published in Scientific Reports reveals that this taste may be rooted in your genes.

Study authors Jue-Sheng Ong, a Ph.D. student at the QIMR Berghofer Medical Research Institute in Australia, worked with Marilyn Cornelis, Ph.D., of the Nortwestern University Feinberg School of Medicine to narrow in on a handful of genes that influence how we perceive bitterness. They believed that these genes might drive a preference for one beverage over the other, which they investigated by analyzing the genetic profiles and beverage consumption habits of 438,870 UK Biobank participants.

Ong tells Inverse that he focused on three genes: one that determines how bitter we find caffeine, one that determines the bitterness of quinine (a compound in both tea and coffee), and one that determines how bitter we find propylthiouracil (PROP) — this is a synthetic chemical, but genes related to PROP sensitivity are often used to measure how someone perceives bitterness in general.

“I think it is fair to say that what we drink is influenced by many factors, some part of it is due to genetics,” Ong says. “Here we are able to show that in a large population, the genetic influence of your ability to taste bitterness does affect your liking of these beverages.”

When it came to coffee, the results initially seemed straightforward: People who were finely attuned to bitterness (as demonstrated by variants leading to high bitterness sensitivity for quinine and PROP) tended to avoid it.

“While our data show that if you have genes that make you able to generally taste bitterness better — like the bitterness of Brussels sprouts and tonic water — you’re less likely to drink lots of coffee,” Ong adds.

These people generally turned to tea to fill their beverage void. Specifically, the researchers noticed an inverse correlation between coffee drinking and tea drinking — so this may be driven partially by the idea that these people tend to find certain compounds in coffee unpalatable. But this may be explained by other factors as well, Cornelis adds.

Ong and Cornelis were surprised to find that coffee drinkers weren’t immune to the drink’s bitter taste. They just were more sensitive to a different bitter compound: caffeine. Their analysis showed that people with genetic markers that allowed them to really distinguish caffeine’s bitter signature were more likely to drink more than four cups of coffee per day.

This might seem to suggest that these coffee drinkers really aren’t in it for the taste. Instead, they’re in it for the rush of caffeine. Over time, Cornelis and Ong both suggest that people may learn to associate this bitterness with a buzz, driving a continuous pattern of consumption.

“Many of us are aware of the psychostimulant effect of caffeine,” Cornelis tells Inverse. “And so people who are very familiar with the taste of caffeine might associate that with the psychostimulant effects of caffeine and therefore continue consuming coffee.”

Overall, Cornelis adds that these findings are just a tiny part of a really complicated picture when it comes to figuring out what drives our preferences for certain caffenated beverages. She adds that established genetic research shows that people actually process caffeine differently which can lead to how much or how often someone chooses to drink coffee.

With this paper, they’re really just adding the genetics of taste into that complicated picture. Opening up another avenue of investigation for why why we love (or hate) these drinks in the first place, and what keeps us coming back.