The Capsicum genus originated in the New World but has been adopted into cuisines around the globe.
It contains as many as five species, with an untold number of variants, giving rise not only to the familiar green bell pepper, but also to paprika and a wide range of “hot peppers.”
The flavors of these fruits have been much appreciated as spices for a very long time. Archaeologists have found remains of chilies in Mexican sites dating to 7000 b.c., and hot peppers played an important role in Aztec and Maya mythology.
The spiciness of edible peppers varies dramatically. The active ingredient in hot peppers, capsaicin, is so strong that people can detect it at a concentration as low as just one part in eleven million.
Most people have no trouble telling a mild pepper from a torrid one, but it was the medicinal use of cayenne that led to a way to compare them consistently.
When capsaicin is applied to the skin, it provokes a feeling of warmth and stimulates circulation in the area. As a consequence, these fruits are popular ingredients in liniments or rubs for arthritis.
Back in 1912 Wilbur Scoville, a pharmacologist working for Parke Davis, needed to standardize the pepper extract used to make Heet Liniment. He started with an organoleptic scale that required a panel of tasters to measure pepper hotness.
Using Scoville’s scale, the capsaicin in a capsicum fruit is currently determined by high-tech machines rather than sensitive palates.
The “hotness” of peppers can range from 3,000 to 5,000 Scoville units for a jalapeño to about 50,000 Scoville units for a cayenne pepper. The very hottest, the habañeros, weigh in at 200,000 to 300,000 Scoville units.
The part of the plant used medicinally is the fruit. To flavor food, it may be used fresh or dried, but in herbal products it is generally dried.
Although referred to as “cayenne,” not all botanicals containing C. annuum are derived from the variety that connoisseurs of hot peppers would recognize as cayenne.
As with other plants, growing conditions and variety can alter the composition of capsicum fruit.
Capsicum peppers are rich in nutrients, especially vitamin C and a range of carotenes. Not only beta-carotene (which is in abundant supply), but also such compounds as lutein, zeaxanthin, and others are found in these fruits.
But the ingredient that is responsible for most of the medicinal effects of cayenne is capsaicin, a pungent phenolic compound structurally similar to eugenol, a pain-relieving compound found in cloves and some other spices.
The principal use of both cayenne and of capsaicin derived from it is in topical ointments or creams. Such rubs have long been used to alleviate joint pain due to arthritis or the pain of muscle spasms.
When applied to the skin, capsicum results in a feeling of warmth, which may in some people become a perception of heat or even of burning.
With repeated applications, the capsaicin depletes substance P from nerves in the skin. Because substance P is apparently crucial to the transmission of pain sensation, its depletion results in diminished pain.
This action led to the development of over-the-counter creams containing 0.025 percent capsaicin to treat postherpetic neuralgia, diabetic , and trigeminal neuralgia. A higher-potency product, Zostrix-HP, with three times as much capsaicin, is also available.
Other painful conditions such as phantom limb syndrome, postmastectomy pain, and reflex sympathetic dystrophy are being studied to see if capsaicin can be helpful.
Preliminary research suggests that capsaicin may be helpful for the treatment of cluster headache, and a nasal spray has been tested at Johns Hopkins Asthma and Allergy Center for the treatment of chronic runny nose.
Traditionally, cayenne was recommended to stimulate the appetite and aid digestion.
Although people often think of chili peppers as irritating to the digestive tract, studies in rats have actually shown that pretreatment of the stomach lining with capsaicin solution (similar to Tabasco sauce) prevented damage from subsequent aspirin exposure.
It also prevented damage due to alcohol; this research was carried out in rats, and its applicability to humans is uncertain. Clinicians have established, however, that capsicum ingestion does not slow the healing of ulcers.
Preliminary studies suggest that chili peppers may help lower cholesterol or slow blood clotting. Further research is needed for confirmation of these uses.
Topical use of capsaicin in over-the-counter or herbal preparations requires repeated applications. Varro E. Tyler suggests four or five applications daily over a period of four weeks.
At least three days of applications are needed to determine the effect. There are no time limits on topical use of cayenne preparations unless you develop a reaction.
Semi-liquid preparations contain 0.02 to 0.05 percent capsaicin; liquids contain 0.005 to 0.01 percent capsaicin; and poultices may contain 10 to 40 g capsaicin and related compounds per square centimeter.
Tolerance of cayenne for internal use varies with the individual. In capsules, the usually recommended dose ranges from 30 to 120 mg three times a day.
Capsaicin-containing preparations must not be applied to broken skin.
Great care must be taken when handling chili peppers or capsaicin creams. Capsaicin is extremely irritating to the eyes or delicate mucous membranes, and it is not very soluble in water.
As a consequence, using the fingers to apply a rub may mean that touching the eyes much later can result in a painful burning sensation. Handling contact lenses could also result in burning eyes. Use of gloves or an applicator may be advisable.
To remove capsaicin from the hands, milk or vinegar may be more effective than water.
Skin treated with capsaicin should not be bandaged or exposed to heating pads.
People with a history of asthma should take care not to inhale capsicum fumes, which can be irritating to the lungs.
Capsaicin may stimulate the bowel and is not generally considered appropriate for people with irritable bowel syndrome or chronic bowel inflammation.
Redness, irritation, stinging, or burning sensations occur in at least 30 percent of people using topical capsaicin preparations, especially when a person has not been applying the cream regularly.
Allergic reactions have been reported on occasion.
Inhalation of powdered cayenne or of fumes from heated or burned chilies can cause coughing or chest tightness in susceptible people.
Ingestion of capsicum fruit can result in burning sensations of the digestive tract. To minimize this problem, reduce the dose, remove the seeds before consuming the peppers, or eat bananas to ease the discomfort.
There have been no reports of capsicum interacting with medications.
If indeed this herb has the potential to prolong clotting time, however, people taking Coumadin or other anticoagulants should exercise caution before eating quantities of chili peppers.
Topical application may not pose a threat of interaction.
Some reports suggest that capsicum may interfere with MAO inhibitors such as Nardil or Parnate and with certain blood pressure medications. Capsaicin inhibits liver enzymes (CYP1A2) and thus slows the metabolism of Anafranil, Clozaril, Cognex, Coumadin, imipramine, theophylline, Zyflo, and Zyprexa.