If you can't get through the morning without a cup of coffee (or two), you might want to look away now, because your caffeine addiction could be altering your taste buds.
Caffeine works by suppressing the adenosine receptors. These things play an important role in sleep and can affect how relaxed or sleepy you feel, which explains why a shot of espresso makes you more alert and energized.
The thing is, it also decreases your ability to taste sweet food. Frustratingly, this may make you crave sugar more.
Researchers at Cornell University ran a blind study to test how caffeine affects our sense of taste. The results were published in the Journal of Food Science earlier this week.
The team split the 107 participants into two groups: One was given a sample of decaffeinated coffee spiked with 200 milligrams of caffeine – roughly the same amount you'll find in a strong cup of coffee – while the second group drank decaffeinated coffee.
Interestingly, even though each coffee drink had been sweetened with the same amount of sugar, those with decaf rated their coffee sweeter than those who'd had caffeine added.
"When you drink caffeinated coffee, it will change how you perceive taste – for however long that effect lasts," says senior author Robin Dando, assistant professor of food science, in a statement. The coffee, however, did not have an influence on bitter, sour, salty, or umami perception.
That isn't all. Researchers then asked participants how alert they felt after drinking the coffee. People from both groups reported similar levels of alertness. They weren't even able to work out if they'd been given the decaff or caffeinated coffee.
It seems that the act of drinking coffee is enough to produce the alertness we associate with the drink. Basically, it has a placebo effect.
"Think Pavlov's dog. The act of drinking coffee – with the aroma and taste – is usually followed by alertness," says Dando. "So the panelists felt alert even if the caffeine was not there."
"What seems to be important is the action of drinking that coffee," he continues. "Just the action of thinking that you've done the things that make you feel more awake, makes you feel more awake."