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Human brains have adapted to like coffee’s bitter flavour, says study

Cup of coffee with coffee beans spilling out of bag

Scientists in Australia believe genetic influences help explain why so many people love the bitter taste of beverages like coffee.

From an evolutionary perspective, when something that you eat or drink tastes bitter it is meant to alert the body that it is harmful and should be ejected forthwith. So why is it that so many people the world over like the bitter taste of coffee?

Indeed, according to a study that explored the genetic influences on perception of caffeine’s taste, people with a higher sensitivity to the bitter caffeine taste drink more coffee. As senior author of the study Marilyn Cornelis, Assistant Professor of Preventive Medicine at the Northwestern University Feinberg School of Medicine in Australia says: “You’d expect that people who are particularly sensitive to the bitter taste of caffeine would drink less coffee. But the opposite results of our study suggest coffee consumers acquire a taste or an ability to detect caffeine due to the learned positive reinforcement — ie, stimulation — elicited by caffeine.”

In other words, people who have a heightened ability to taste coffee’s bitterness — and particularly the distinct bitter flavour of caffeine — learn to associate “good things with it,” Cornelis says.

The study, which involved collaboration between Northwestern University researchers and colleagues at Brisbane’s QIMR Berghofer Medical Research Institute, has been published by Scientific Reports and involved testing the causal relationship between bitter taste and beverage consumption in more than 400,000 men and women in the UK.

The researchers concluded that the more sensitive people are to the bitter taste of caffeine, the more coffee they drink, and that that sensitivity is caused by a genetic variant.

In the study population, people who were more sensitive to caffeine and were drinking a lot of coffee consumed low amounts of tea. But that could just be because they were too busy drinking coffee, Cornelis points out.

The study also found people sensitive to the bitter flavours of quinine and PROP, a synthetic taste related to the compounds in cruciferous vegetables such as cauliflower, cabbage and brussels sprouts, avoided coffee. For alcohol, a higher sensitivity to the bitterness of PROP resulted in lower alcohol consumption, particularly of red wine.

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

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