The bitterness of coffee is actually why you love it so much, study finds

CHICAGO — If you love your daily jolt of joe, it could be because of your heightened genetic sensitivity to bitter tastes. That’s right. You prefer coffee over tea because you are attracted to the bitterness, believe it or not, according to a recent study.

Researchers at Northwestern University have found that drinking coffee defies evolutionary logic. Human taste buds have learned over time to spit out bitter-tasting substances. So it would seem logical that people who drink coffee have underdeveloped taste buds.

That would be an incorrect assumption. Coffee drinkers, it turns out, love coffee because of its bitterness. Their taste buds are actually more sensitive to bitter flavors, particularly the uniquely bitter taste of caffeine. They have come to associate that strong flavor with a greater jolt of stimulating good feelings. Thus, a preference for coffee over tea is all in our genes.

“You’d expect that people who are particularly sensitive to the bitter taste of caffeine would drink less coffee,” says Marilyn Cornelis, an assistant professor of preventive medicine at the university’s Feinberg School of Medicine, in a news release. “The opposite results of our study suggest coffee consumers acquire a taste or an ability to detect caffeine due to the learned positive reinforcement (i.e., stimulation) elicited by caffeine.”

Scientists used what’s known as the Mendelian randomization method to determine the influence of genetic variations on coffee, tea and alcohol consumption. More than 400,000 men and women from the United Kingdom participated in the study. Researchers considered the genetic variants involved in identifying caffeine, quinine and PROP (an artificial taste associated with the compounds of cruciferous vegetables). Participants self-reported on the amount of coffee, tea and alcohol they consume.

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The authors found that participants with heightened sensitivity to caffeine’s bitter flavors drank a lot more coffee and a lot less tea. Cornelis notes that these results could simply be because participants were drinking so much coffee, they did not have time to drink tea.

The study determined that those who are more sensitive to quinine and PROP shun coffee. Participants who could more easily detect the bitter flavors of PROP in cruciferous vegetables were less likely to drink alcohol, especially red wine.

“The findings suggest our perception of bitter tastes, informed by our genetics, contributes to the preference for coffee, tea and alcohol,” Cornelis says.

With such strong opinions voiced by our beverages of choice, researchers want to know more about what is going on behind the scenes.

“Taste has been studied for a long time, but we don’t know the full mechanics of it,” Cornelis said. “Taste is one of the senses. We want to understand it from a biological standpoint.”

For coffee drinkers, there is no need to apologize. You just know it’s better when it’s bitter.

The study was published in the November 15, 2018 edition of Scientific Reports.

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