Bitter equals poisonous - at least according to our brain. There seems to exist only one exception from this evolutionary dislike for bitterness: coffee. Why many of us cannot even imagine a morning without a cup of espresso or latte, although its bitter taste should make our body issue a poison alert?
Researchers from the Northwestern Medicine and QIMR Berghofer Medical Research Institute in Australia discovered that, paradoxically, genetic sensitivity to bitter taste makes us even more likely to drink larger amounts of coffee.
“You’d expect that people who are particularly sensitive to the bitter taste of caffeine would drink less coffee,” argues Dr. Marilyn Cornelis, the assistant professor of preventive medicine at the Northwestern University Feinberg School of Medicine in Chicago and senior author of the study. “The opposite results of our study suggest coffee consumers acquire a taste or an ability to detect caffeine due to the learned positive reinforcement (i.e. stimulation) elicited by caffeine.”
This means that people with high sensitivity to bitterness of caffeine form positive associations with coffee - and enjoy more cups a day than their friends without this genetic variant.
Researchers studied genes and daily coffee consumption of over 40,000 participants from the UK. “Using the genes related to our ability to taste bitterness, we were able to assess whether those that have a higher genetic predisposition to tasting bitterness are more likely to prefer tea over coffee,” explained Jue Sheng Ong, the lead author of the paper, a PhD student in the Department of Genetics and Computational Biology at the QIMR Berghofer Medical Research Institute in Brisbane.
They found out that people with genes responsible for recognising the bitterness of tonic water or green vegetables, for example Brussel sprouts, tend to prefer tea over coffee. Interestingly, in comparison to people without such gene variants, they are also less likely to drink alcohol, in particular red wine. This result could potentially help improving treatments for alcohol addictions.
Ong admitted that they did not consider milk, cream, sugar or other additions often put into coffee cups. They focused on the general links between genes and coffee consumption.
Taste remains one of our most secretive senses, but this study contributed to its understanding. And I will stop fighting my coffee addiction - what can I do, it’s in my genes!