Scientists Discover Hidden ‘Anti-Spice’ Compounds In Chili Peppers That Turn Down The Heat

COLUMBUS, Ohio — Ever wondered why some chili peppers burn your mouth more than others, even when they contain the same amount of capsaicin? A study out of Ohio State University shows that chili peppers also harbor natural compounds that act like built-in fire extinguishers—suppressing the fiery sensation we associate with spicy food.

Researchers identified five compounds in chili peppers that were negatively correlated with perceived pungency. Of those, three — capsianoside I, roseoside, and gingerglycolipid A — were shown to significantly reduce the burn when consumed alongside capsaicin, the compound typically blamed for chili heat.

This discovery adds a surprising twist to what actually determines how hot a pepper feels.

“Despite normalizing for the total amount of the two major capsaicinoids (capsaicin and dihydrocapsaicin), the maximum intensity ranged from 7.1 to 11.8 units across the samples,” the researchers note in their paper, published in the Journal of Agricultural and Food Chemistry. Even when peppers contained identical amounts of the compounds traditionally thought to cause spiciness, they felt dramatically different to taste testers.

Consider two glasses of water, each with the same dose of hot sauce. Conventional wisdom says they’d taste equally spicy. But the study shows that one might contain natural “cooling” compounds that significantly reduce the perceived burn — even if the capsaicin levels are identical.

When the researchers added capsianoside I, roseoside, and gingerglycolipid A to a capsaicin solution, trained sensory panelists consistently rated the mixtures as less spicy than capsaicin alone.

Putting Anti-Spice Theory To The Test

To explore this mystery, scientists analyzed ten varieties of chili peppers from four Capsicum species, including familiar types like Serrano and Scotch Bonnet as well as more exotic ones like African Bird’s Eye and Wiri Wiri. They adjusted all pepper samples to contain the same amount of capsaicin and dihydrocapsaicin—equivalent to 800 Scoville Heat Units—before testing began.

Nine trained panelists evaluated the peppers using time-intensity analysis, rating the burn sensation over eight minutes. But to get an even more precise comparison, the team employed a “half-tongue” test: 37 volunteers had filter papers soaked in either pure capsaicin or capsaicin plus one of the suppressing compounds applied to opposite sides of their tongue at the same time.

Participants consistently judged the capsaicin-only side as more intense. The suppressing compounds reduced perceived heat by 0.7 to 1.2 points on a 15-point scale—a statistically significant and perceptible difference.

How These Natural Fire Suppressors Work

While the exact mechanism is still being investigated, the researchers propose that these compounds may reduce capsaicin’s interaction with TRPV1 receptors—the molecular sensors responsible for detecting heat and pain. One of the compounds, gingerglycolipid A, has previously been shown in animal studies to activate TRPV1 without causing a burning sensation, suggesting it may block capsaicin’s full effect.

When tested alone in water, the three compounds had no detectable taste. Their role seems to be purely as modulators, influencing the body’s heat sensors without contributing flavor of their own.

What This Means for Spicy Food Lovers

This discovery helps explain why some peppers feel milder than others despite high capsaicin levels—and why the Scoville scale doesn’t always reflect what your mouth feels. It turns out that pungency isn’t just about how much capsaicin is present, but also about what other compounds are tagging along.

Food manufacturers could potentially use these natural suppressors to engineer more precisely tuned spicy products. Meanwhile, pepper breeders may someday select for specific combinations of these compounds to dial the heat up or down without touching capsaicin content.

“If you’re at home and you’ve ordered cuisine that has spice to it that’s a little too hot for some tastes, you can just sprinkle on a form of chili pepper that has got these suppressant agents in them that will dial it down,” said senior study author Devin Peterson, a professor of food science and technology at The Ohio State University in a statement. “I think the idea of using a natural material as an anti-spice, especially for somebody with kids, would have value as a household ingredient.”