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Marilyn Cornelis has been thinking about coffee for most of her life. As a child, Professor of Preventive Medicine at the Feinberg School of Medicine at Northwestern University watched her father one cup at a time, "two pots a day," and made sure that his siblings dared to lick the spoon with which he moved. "It was so bitter for us," she says, her voice still recording a bit of shock.
This reaction to bitter tastes is universal and it is coded in our DNA – at a time when humans were constantly having to fetch food to survive, an aversion to bitter tastes prevented people from sticking to their mouths with poisoned things . out of hunger. Humans who hated bitter tastes lived to look for food the other day, giving them the opportunity to breed offspring who are currently lining up at Starbucks.
Cornelis, whose academic research is focused on genetics and caffeine throughout her career, is sometimes part of it, she admits, although it needs milk and sugar to make her lose herself. "I still can not drink the black," she says. Yet in a study published by Cornelis on Thursday, she and her colleagues at the QIMR Berghofer Medical Research Institute in Australia found that people who are genetically predisposed to be sensitive to the bitter taste of caffeine drink more coffee than those who are less sensitive to caffeine. to other bitter tastes such as quinine.
Cornelis says the discovery was surprising. "In general, humans avoid bitter flavors, and caffeine is one of those compounds, but people who are genetically sensitive to the taste of caffeine drink more coffee, so it may be that when you taste caffeine you have learned stimulating effects of caffeine. "
In other words, the desire for the stimulating effects of caffeine is so strong that we are ready to look for a bitter taste to get it.
This stimulant-seeking behavior is controlled by different genetic variants – those that control the body's ability to metabolize caffeine. If your genes are programmed to metabolize caffeine effectively, you will burn more quickly its stimulating effect. That's why you will spend more time in coffee than your colleagues. "We are all constantly titrating our own caffeine," said Cornelis.
She and other researchers have identified about eight genetic variants that affect caffeine metabolism and, as a result, predict levels of consumption. But a genetic test for coffee addicts is not what researchers are looking for. Instead, studying caffeine and genetics may one day reveal some of the mysteries of the protective effects of caffeine on health in general and on diseases such as diabetes and heart disease.
Large-scale studies have shown a link between shelf life and coffee consumption – people who drink about four cups a day live longer and, as scientists strive to understand these effects, may use this knowledge to fight the disease.
The genetic link with bitter tastes has also been studied with care. Scientists have shown that supertasters, which have more taste buds and taste everything more vividly than the rest of us, tend to avoid strong spices and have a stronger dislike for the taste buds. bitter. On the other hand, there are some special cases that express a true as for bitter tastes (compared to a learned tolerance). Correlations have been shown between this affinity for bitter tastes and "malicious traits associated with a psychopathic personality, particularly the characteristic known as" daily sadism, "writes Rachel Herz, neuroscientist at Brown University.
Herz's book titled "Why You Eat What You Eat" explores the intersection of science and eating habits, and also points out that the enjoyment of bitter tastes has implications for alcohol consumption and the consumption of alcohol. vulnerability to alcoholism. A study conducted at the University of Indiana showed that beer drinkers had a dopamine release mimicking the feeling of being intoxicated simply by tasting a bitter taste like the beer. This is a classic Pavlovian answer: to transfer the answer to beer into a simple taste signal. Study participants with a family history of alcoholism found an even greater release of dopamine by the bitter taste, indicating a genetic predisposition to expect a bitter taste reward.
Most of us who queue for coffee, however, do not have affinity for bitter tastes. Part of the coffee draw can be explained by cultural and even meteorological considerations – people in cold weather tend to drink more coffee.
Chicago, the city of posters for cold winters, has always been a big consumer of coffee (we had the first Starbucks store in 1987), and it's nothing compared to places like Finland, where coffee consumption by inhabitant is about twice that the United States
But Cornelis (who has never drunk coffee before moving to Chicago) says his research simply shows that those who are sensitive to the taste of caffeine are naturally eager to find it for the purpose. to get that little extra boost of energy. They can still enjoy the taste of something sweet better – which brings us back to coffee.
According to Cornelis, the genius of Starbucks is not that it is perfectly positioned to take advantage of human genetics or a profusion of acquired experiences. "Where Starbucks is really involved," she says, "is that the bitterness of the coffee can be easily masked, so they always come out with a new drink, a new flavor." Caffeine is what we all seek, but for most of us, there is only one question that matters, she says: "It's all about" What do you want? you in your drink? "
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