Marilyn Cornelis has thought of coffee for most of her life. As a child, Northwestern University professor of preventive medicine at the University of Feinberg observed his father under cup by cup – "several pots a day" and made a game challenging his brothers to lick the spoon he used to stir it. "It's very bitter for us," he said, his voice still slightly tapering.
The reaction to bitter taste is universal, and it is encoded into our DNA – when humans are needed to constantly search for food to sustain life, a hatred of the bitter taste makes people not put toxic things into their mouths when they try to prevent hunger. Humans who hate the bitter taste of life are looking for food on other days, which gives them the opportunity to spawn offspring, who are currently lining up at Starbucks.
Cornelis, whose academic research centered on genetics and caffeine for his entire career, sometimes among them, he acknowledged, although it needed milk and sugar to get him down from bitter drinks. "I still can't drink it black," he said. However, in a study published by Cornelis on Thursday, he and his colleagues at QIMR Berghofer Medical Research Institute in Australia found that people who genetically tend to be sensitive to the bitter taste of caffeine drink more coffee than those who are less sensitive or those who are sensitive against other bitter tastes like quinine.
Cornelis said the discovery was surprising. "Usually, humans avoid bitter taste, and caffeine is one of those compounds, but people who are genetically sensitive to caffeine taste really drink more coffee. So maybe when you feel caffeine, you have learned to connect it with a caffeine stimulant effect. "
In other words, the desire for the stimulant effect of caffeine is so strong, we are willing to look for the bitter taste to get it.
Stimulant seeking behavior is controlled by different genetic variants – they control the body's ability to metabolize caffeine. If your genes are programmed to metabolize caffeine efficiently, you will burn through the stimulant effect more quickly, which is why you will spend more time in office than your coworkers. "We all continue to do our own caffeine titration," Cornelis said.
He and other researchers have identified about eight genetic variants that act on caffeine metabolism and, as a result, predict consumption levels. But genetic testing for coffee addicts is not what researchers want. Conversely, studying caffeine and genetics might one day open up some mysteries of the effects of caffeine protection on general health and diseases such as diabetes and heart disease.
Large-scale studies have shown an association between age and coffee consumption – people who drink about four cups per day live longer, and when scientists work to understand these effects, they may be able to use that knowledge to fight disease.
Genetic relationships with bitter taste have also been carefully studied. Scientists have shown that supertaster, which has more taster and really feels everything more clearly than all of us, tends to avoid strong spices and has a stronger aversion to bitter. On the other hand, there are a number of outliers that say true like bitter taste (versus tolerance learned). Correlation has been shown between this affinity for bitter taste and "the evil nature associated with psychopathic personality, specifically the characteristic known as" sadism every day "," wrote Brown University neurologist Rachel Herz.
Herz Books & # 39; Why You Eat What You Eat & # 39; explore the intersection of science and eating habits, and also show that bitter taste pleasure has implications for drinking and susceptibility to alcoholism. A study at Indiana University shows that beer drinkers experience dopamine release that mimics the feeling of being drunk just by tasting bitter taste like beer. This is the classic Pavlovian response: transferring responses to beer to a simple taste signal. Study participants with a family history of alcoholism experienced greater dopamine release than bitter taste, signaling a genetic tendency to expect a reward from a bitter taste.
Most of us who are lining up for coffee, however, do not have an affinity for bitter taste. Part of the draw to the coffee shop can be explained by cultural considerations and even meteorology – people in cold weather climates tend to drink more coffee.
Chicago, the city of posters for winter, has always been a big consumer of coffee (we were home to Starbucks's first expansion store in 1987), and that's nothing compared to places like Finland, where per capita coffee consumption is about twice that of America Union
But Cornelis (who never drank coffee until he moved to Chicago) said that his research only shows that those who are sensitive to the taste of caffeine are naturally accustomed to finding it, in an effort to get extra bursts of energy. They may still like the taste of something sweeter – which brings us back to the coffee shop.
The genius of Starbucks, said Cornelis, is not perfectly positioned to take advantage of human genetics or thousands of years of learning experience. "Where Starbucks really gets noticed," he said, "is that the bitterness of coffee can be easily disguised. So they always come out with new drinks, new flavors." Caffeine is what we are all looking for, but for most of us, there is only one important question, he said: "It's all about & # 39; What else do you want in your drink? & # 39;"