CHICAGO Marilyn Cornelis has been thinking about coffee for most of her life. As a child, the Northwestern University Feinberg School of Medicine preventive medicine professor watched her father down cup after cup a couple of pots a day and made a game of daring her siblings to lick the spoon he used to stir it. It was so bitter to us, she says, her voice still registering a little of the face-twisting shock.
That reaction to bitter tastes is universal, and its coded into our DNA at a time when human beings needed to constantly seek food to sustain life, an aversion to bitter tastes kept people from jamming poisonous things into their mouths as they sought to stave off hunger. Humans who hated bitter tastes lived to forage another day, which gave them the opportunity to spawn descendants, who are currently standing in line at Starbucks.
Cornelis, whose academic research has centered on genetics and caffeine for her entire career, is sometimes among them, she admits, though it takes some milk and sugar to get her to down the bitter brew. I still cant drink it black, she says. Yet, in research published by Cornelis earlier this month, she and 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 or those who are sensitive to other bitter tastes such as quinine.
Cornelis says the finding was surprising. Typically, humans avoid bitter tastes, and caffeine is one of those compounds, but people who were genetically sensitive to the taste of caffeine actually drank more coffee. So it might be that when you taste caffeine, you have learned to link that to the stimulant effects of caffeine.
In other words, the desire for the stimulant effects of caffeine is so strong, we are willing to seek out a bitter taste in order to get it.
That stimulant-seeking behavior is controlled by different genetic variants those that control the bodys ability to metabolize caffeine. If your genes are programmed to metabolize caffeine efficiently, you will burn through its stimulant effect more quickly, which is why youll spend more time at the office coffee pot than colleagues. We are all sort of constantly titrating our own caffeine levels, says Cornelis.
But a genetic test for coffee junkies isnt what researchers are after. Instead, studying caffeine and genetics may one day unlock some of the mysteries of caffeines protective effects on general health and diseases like diabetes and heart disease.
Large-scale studies have shown a link between lifespan and coffee consumption people who drink around four cups per day live longer, and as scientists work to understand those effects, they may be able to harness that knowledge to combat disease.
But Cornelis says her research simply shows that those who are sensitive to the taste of caffeine are naturally attuned to finding it, in an effort to get that little extra burst of energy. They still may like the taste of something sugary better which brings us back to the coffee shop.
The genius of Starbucks, says Cornelis, isnt that it is perfectly positioned to take advantage of human genetics or eons of learned experience. Where Starbucks is really keyed in, she says, is that the bitterness of coffee can be easily masked. Its all about What else do you want in your drink?
