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For All the Coffee and Chocolate

Researchers have tied genetic variation associated with the faster metabolism of caffeine to a preference for drinking coffee black and for eating dark chocolate, WTTW in Chicago reports.

In a new analysis, Marilyn Cornelis from Northwestern University and Rob van Dam of George Washington University examined whether loci linked through genome-wide association studies to taste were also tied to drinking black coffee or drinking coffee with milk or sugar using data from the UK Biobank and elsewhere. Moderate coffee consumption and the consumption of dark chocolate have been linked to lower risk of some diseases like Parkinson's disease, heart disease, and type 2 diabetes, WTTW notes.

As they write in Scientific Reports this week, the researchers found that while bitter taste perception was linked to coffee consumption, there was a stronger link between genetically determined caffeine sensitivity and drinking black coffee. They further found a similar pattern for dark chocolate and, to a lesser extent, for tea.

"Our interpretation is these people equate caffeine's natural bitterness with a psycho-stimulation effect," Cornelis says, according to WTTW. "They learn to associate bitterness with caffeine and the boost they feel. We are seeing a learned effect."