People who like to order their coffee very dark for breakfast or after dinner also prefer other bitter drinks such as dark chocolate, a new study from Northwestern Medicine has revealed. Interestingly, the reason must be found in their genes.
Scientists at this center have discovered that coffee drinkers who have a genetic variant that reflects a faster metabolism of caffeine prefer bitter black coffee. And the same genetic variant is found in people who prefer the bitterest dark chocolate to the smoothest milk chocolate.
The reason is not because they like the taste, but rather because they associate the bitter taste with the boost in mental alertness they expect from caffeine. “That’s interesting because these genetic variants are related to faster metabolism of caffeine and are not related to taste,” said the study’s lead author, Marilyn Cornelis, an associate professor of preventive medicine in nutrition. “These people metabolize caffeine faster, so the stimulant effects wear off faster as well. So, they need to drink more.”
These new findings are believed to enhance future research on the health benefits of coffee and dark chocolate.
“Our interpretation is that these people equate the natural bitterness of caffeine with a psychostimulatory effect,” Cornelis said. “They learn to associate bitterness with caffeine and the rush they feel. We are seeing a learned effect. When they think of caffeine, they think of a bitter taste, so they enjoy black coffee and, similarly, dark chocolate.” according to the conclusions of the article that has been published in Scientific Reports.
The dark chocolate connection may also be related to the fact that it contains a small amount of caffeine, but predominantly theobromine, a compound related to caffeine, also a psychostimulant.
Why is this link between genetics, coffee and health important?
The consumption of coffee and dark chocolate has been shown to reduce the risk of certain diseases. Thus, moderate coffee consumption reduces the risk of Parkinson’s disease, cardiovascular disease, type 2 diabetes and several types of cancer. Dark chocolate, meanwhile, appears to reduce the risk of heart disease.
Currently, when scientists study the health benefits of coffee and dark chocolate, they must rely on epidemiological studies, which only confer an association with health benefits rather than a stronger causal link.
Cornelis’ new research shows that these genetic variants can be used more precisely to study the relationship between coffee and health benefits. Previously, scientists used genetic markers for coffee drinkers in general. The new findings suggest that they are stronger markers for particular types of coffee drinkers: black coffee drinkers. This impacts the interpretation of these genetic studies of coffee and health.
“Drinking black coffee versus coffee with cream and sugar is very different for your health,” Cornelis said. “The person who wants black coffee is different from a person who wants coffee with cream and sugar. According to our findings, the person who drinks black coffee also prefers other bitter foods such as dark chocolate. So we’re digging deeper into a more accurate way to measure the actual health benefits of this drink and other foods.”
The benefits of black coffee are based on a moderate consumption of two to three cups a day, Cornelis explained. The current study used genetic, dietary, and food preference data available from the UK Biobank and two US cohorts, the Nurses’ Health Study and the Health Professionals Follow-up Study.
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