Living With Herbs: Fire Power

It doesn't matter who you are, or what you've done, or what you think you can do. There's a confrontation with destiny awaiting you. Somewhere, there's a chile pepper you cannot eat.
—Daniel Pinkwater

It's a mystery. How can an herb that causes an intense burning sensation, tears, and sweating be one of the most popular in America? And how can a plant that packs a painfully disabling wallop also lessen the disabling pain of arthritis, shingles, and herpes? Mystery or not, it's a fact. The popular, painful chile pepper can knock you down—and pick you right up again.

The most fascinating feature of the chile pepper is its ability to inflict pain and create pleasure at the same time. This personality quirk is caused by a plant alkaloid called capsaicin (cap-say-a-cin), unique to chiles, which causes the sensation of heat. How hot? The chile pepper's fire power is measured in "Scoville units," named for the courageous taste-tester Wilbur Scoville. On the Scoville scale, a bell pepper clocks in at 0 units, a jalapeño at 5,000, and the fiery habanero at a blistering 300,000. Capsaicin itself is an inferno, measured at 15 million units. When you're in pain (a natural consequence of eating a jalapeño), the nerve endings release a neurotransmitter called Substance P, which travels to the brain with the message, "Hey, I'm hurting!" In response, the brain releases neurotransmitters called endorphins, which produce the pleasurable sense of well-being that chile-heads call "the hot sauce high."

Something similar happens when peppers are used medicinally. In an ointment, capsaicin has been shown to reduce arthritis pain and inflammation, ease cluster headaches, prevent herpes flare-ups, treat psoriasis, and alleviate surgical and burn pain. Dr. Roy Altman, of the University of Miami School for Medicine says: "The mystery is that it took us so long to figure out just how to use this stuff."

For more (lots and lots more!) about chiles:
The Chile Pepper Encyclopedia, by Dave Dewitt