When it comes to tolerating spicy foods, not all mouths are created equal. Findings published today in the journal Science help explain why that is the case. Researchers have identified a lipid molecule that plays a critical role in controlling the severity of a burning sensation.

Scientists have known for some time that it is a compound known as capsaicin that gives chili peppers their kick. In the mouth, the capsaicin receptor (TRPV1) governs the level of pain that can accompany a spicy meal. Elizabeth D. Prescott and David Julius of the University of California, San Francisco, investigated a specific binding site within TRPV1. They discovered that a lipid molecule known as PIP2 is usually bound to the receptor, but in the presence of capsaicin, it is released, creating a painful sensation. The strength with which PIP2 is bound to TRPV1, the researchers found, thus determines how sensitive the neurons are to the spice.

For the average person, the amount of heat that is tolerable merely influences food choice. But the new results could hold promise for sufferers of oral conditions such as Burning Mouth Syndrome. The authors suggest that modification of PIP2 binding--perhaps by genetic, biochemical or pharmacological means--could make mouth nerves much less receptive and thus ease the burn.