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The Journal Gazette

Sunday, September 10, 2017 1:00 am

Caffeine can bolster our craving for sweets

Maura Judkis | Washington Post

If you're frequently tempted to buy a treat from the pastry case at your favorite coffee shop, there's a good reason – and it's not just your lack of willpower. A new study on coffee has found that caffeine can affect the way we perceive sweetness and might make us crave sweets more strongly.

Caffeine gives us an energy jolt because it blocks receptors in our brain for adenosine, a chemical that can make us feel sleepy. Previous research established that adenosine also helps us taste sweet flavors.

For this study, a team of scientists at Cornell University gave participants a cup of lightly sweetened coffee, and didn't tell them whether it contained caffeine (the purely decaf cups contained quinine, to make sure both types of coffee had the same level of bitterness). The participants were “unable to estimate the caffeine content of their sample,” the study said, which confirms “the strong placebo effect to coffee consumption.”

But even though many of the participants guessed there was a normal amount of caffeine in their cups, the ones who drank caffeine perceived their coffee to be less sweet than those who unknowingly drank decaf. When the participants were asked to taste and rate a sucrose solution more than 15 minutes later, the caffeinated participants still reported tasting lower levels of sweetness.