According to a new study published in the Journal of Food Science, caffeine tempers taste buds temporarily, making food and drink seem less sweet.

“Caffeine is a powerful antagonist of adenosine receptors, which promote relaxation and sleepiness,” the study authors said.

“Suppressing the receptors awakens people but decreases their ability to taste sweetness — which, ironically, may make them desire it more.”

“Our research demonstrates taste modulation in the real world,” said senior author Dr. Robin Dando, of Cornell University.

“When you drink caffeinated coffee, it will change how you perceive taste — for however long that effect lasts.”

“So if you eat food directly after drinking a caffeinated coffee or other caffeinated drinks, you will likely perceive food differently.”

In the blind study, 107 participants were assigned to two groups, sampling decaffeinated coffee supplemented with either 200 mg of caffeine (about the level found in a strong cup of coffee) or an equally bitter concentration of quinine. Both groups had sugar added.

Participants who drank the caffeinated brew rated it as less sweet.

In a secondary part of the study, the participants disclosed their level of alertness and estimated the amount of caffeine in their coffee.

Further, they reported the same increase in alertness after drinking either the caffeinated or decaffeinated samples, all the while panelists could not predict if they had consumed the decaffeinated or the caffeinated version.

“We think there might be a placebo or a conditioning effect to the simple action of drinking coffee,” Dr. Dando said.

“Think Pavlov’s dog. The act of drinking coffee — with the aroma and taste — is usually followed by alertness. 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 added.

“Just the action of thinking that you’ve done the things that make you feel more awake, makes you feel more awake.”

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Ezen Choo et al. Caffeine May Reduce Perceived Sweet Taste in Humans, Supporting Evidence that Adenosine Receptors Modulate Taste. Journal of Food Science, published online August 23, 2017; doi: 10.1111/1750-3841.13836