Spicy food lovers are likely to be familiar with one immediate physical reaction — sweating.
That’s because some of the spiciest foods contain compounds that bind to nerve receptors along the gastrointestinal tract, including the mouth, which are activatedby heat.
Chillies, the flavourful backbone of many spicy dishes, contain the compound capsaicin, which binds to those receptors and then sends a pain signal to the brain, as Julius discovered in his Nobel Prize-winning work on the topic.
The main chemicals found in peppercorns, horseradish and mustard also bind to the same receptors, albeit much less potently.
These nerves send similar signals to the brain as they would if you came into contact with actual fire, which is why you might start sweating or become flushed; that’s the body’s way of cooling itself down.
“Capsaicin fools your body into thinking the temperature has risen, and so your brain thinks it needs to shed heat,” Julius said. “In humans, we mostly do that by sweating.”
Eating spicy food can produce a variety of physiological reactions, such as a tingling in the tongue and lips, as well as sweating, said David Julius, who is a physiologist at the University of California, San Francisco in the US.