People who prefer their coffee black also tend to prefer dark chocolate, according to new research that may have implications regarding both consumer preference and human health.
The reason those preferences are aligned, according the study author, Northwestern University Associate Professor of Preventive Medicine Marilyn Cornelis, is due to a common genetic variant.
The research shows that coffee drinkers who more quickly metabolize caffeine prefer black coffee for its bitter taste. The same genetic variant exists for people who prefer more bitter dark chocolate over smoother milk chocolate.
However, the preference is not strictly a matter of taste, but rather psychoactive stimulus. Cornelis was also behind the 2018 study that found that people who prefer black coffee for its bitterness do so because they associate it with the mental boost they get from the caffeine.
“Our interpretation is these people equate caffeine’s natural bitterness with a psycho-stimulation effect,” Cornelis said in an announcement of the most recent studies. “They learn to associate bitterness with caffeine and the boost they feel. We are seeing a learned effect. When they think of caffeine, they think of a bitter taste, so they enjoy dark coffee and, likewise, dark chocolate.”
Both studies used data from the UK Biobank project. The most recent paper, “Genetic determinants of liking and intake of coffee and other bitter foods and beverages,” was published last month in Scientific Reports.