Coffee’s bitterness is a natural warning system

Researchers at Northwestern University say that given its bitter taste people should want to spit it out, but drink it they do, because that bitterness is a natural warning system.

It turns out that the more sensitive people are to the bitter taste of caffeine, the more coffee they drink, concluded researchers from Northwestern Medicine and QIMR Berghofer Medical Research Institute in Australia.

That sensitivity is caused by a genetic variant, the researchers said in a study published by EurekAlert, the online publication of the American Association for the Advancement of Science.

While one would expect people who are particularly sensitive to the bitter taste of caffeine would drink less coffee the opposite results suggest coffee consumers acquire a taste or an ability to detect caffeine due to the learned positive reinforcement elicited by caffeine, said Marilyn Cornelis, assistant professor of preventive medicine at Northwestern’s Feinberg School of Medicine.

In other words, people who have a heightened ability to taste coffee’s bitterness, and particularly the distinct bitter flavor of caffeine, learn to associate good things with it, Carnelis said.

The study was published on Nov. 15 in Scientific Reports.


The study also found that people sensitive to the bitter flavors of quinine and of PROP, a synthetic taste related to compounds in cruciferous vegetables like cabbage, broccoli, cauliflower, kale and bok choy, avoided coffee. For alcohol, a higher sensitivity to the bitterness of PROP resulted in lower alcohol consumption, particularly of red wine, researchers said.