The burning sensation caused by hot chili peppers is due to special chemical compounds called capsaicinoids. Professor Joshua Tewksbury of the University of Washington has compelling evidence to support his theory that the plant produces these chemicals to protect itself against grazing animals, harmful bacteria and fungi. The potent chemicals in hot peppers are isolated for human use in ointments and salves to reduce painful inflammation.
Capsaicin
Capsaicin is the most predominant capsaicinoid that causes the burning sensation in hot peppers. The Scoville heat units (SHU), a scale that indicates the amount of capsaicin present, rates pure capsaicin at 15,000,000 to 16,000,000. By comparison, a jalapeño pepper falls between 2,500 and 8,000 SHUs. Capsaicin is typically 22 percent of a hot peeper's chemical makeup. This is also the primary ingredient in defensive pepper sprays.
Dihydrocapsaicin
Dihydrocapsaicin is the second most pungent ingredient in hot peppers. This chemical is usually 22 percent of the total capsaicinoid content in chili peppers. The balance of this compound and capsaicin account for most of this plant's flavor, which gardeners have been cultivating since 7,500 B.C.
Minor Capsaicinoids
To a lesser degree, minor capsaicinoids also influence the warming effect of hot peppers. Clinical Herbalist Todd Caldecott notes that cayenne peppers contain 7.4 percent nordihydrocapsaicin, 2 percent homodihydrocapsaicin and 2 percent homocapsaicin. Although these chemicals trigger a burning sensation on their own, the fact that they exist in trace amounts in peppers diminishes their overall effect.
Medical Use
The University of Maryland Medical Center (UMMC) explains that capsaicin is a counterirritant that temporarily counteracts a body chemical called substance P, which carries pain messages to the brain. When substance P is depleted, the pain messages no longer reach the brain, thus bringing relief to the patient.
Warning
Hot peppers can cause painful burning, which is easily diluted with vinegar or milk. Hot pepper can also cause stomach upset. People with allergies to latex, bananas, kiwi, chestnuts and avocado have also reported allergic symptoms to chili peppers.
