The chili pepper is a member of the deadly nightshade family, Solanaceae, which includes potatoes (Solanum tuberosum L.) except for sweet potatoes, the berry fruit of tomatoes (Solanum lycopersicum), eggplants (Solanum melongena), tobacco (Nicotiana tabacum), and the poisonous deadly nightshade (Atropa belladonna). The chili plants originated in Central and South America, as well as the Caribbean, and were first cultivated over 5,000 years ago. Chilies are one of the world’s most used spices, which includes the dried forms of chili powder, cayenne, and paprika. There are 2,000 to 3,000 varieties of chilies grown, but only a few are commonly grown. The five domesticated species of chili peppers that are commonly grown are Capsicum annuum, Capsicum chinense, Capsicum frutescens, Capsicum pubescens, and Capsicum baccatum.
Chili species are diverse, but what the chilies have in common is that they contain the chemical trans-8-methyl-N-vanillyl-6-nonenamide. This chemical is known by the common name of capsaicin, and it is the active component in chilies that causes a burning sensation when ingested or topically applied. The Scoville scale measures the “hotness” of a chili pepper or any products that are derived from chili peppers, such as hot sauce. This scale is named after Wilbur Scoville, who developed the test in 1912; at certain levels, capsaicin can be injurious or lethal. For example, pepper spray is oleoresin capsicum derived from the oil of capsaicin, with a Scoville rating of 2,000,000 to 5,300,000 Scoville heat units. This can cause several types of injuries, some life threatening. Skin exposure to pepper spray can cause concentrated pain, burning of the skin, and even blistering. Pepper spray exposure can aggravate skin conditions like allergic dermatitis. Oleoresin capsicum can cause a burning pain in the eyes and inflammation, as well as temporary blindness and long-term eye damage such as corneal abrasions. Pepper spray can cause a burning throat, wheezing, gagging, and general difficulty with breathing. In more pronounced cases, oleoresin capsicum can cause laryngospasm, which is an inability to speak or breathe. This is dangerous for people who have respiratory problems such as asthma or who have heart disease. Pepper spray, in some incidences, can cause life-threatening anaphylactic shock.
The oleoresin capsicum in pepper spray is not the only dangerous ingredient. Pepper spray is impure capsaicin and has numerous additives that can add to the capsaicin’s injurious capacity. The chemical mixture, depending on the brand, may include water, alcohol, or organic solvents as liquid carriers and propellants to discharge the spray, such as nitrogen, carbon dioxide, or halogenated hydrocarbons such as Freon (used in air conditioning coolant), tetrachloroethylene (used for dry-cleaning and metal degreasing), and methylene chloride (used in paint removal technology and metal degreasing).
While capsaicin is sometimes used for injurious purposes, the chemicals in chilies can be useful. There is some evidence, but still scientific doubt, about capsaicin creams that are used to treat osteoarthritis pain and may alleviate diabetic neuropathy. Osteoarthritis is a degenerative disease where the protective cartilage on the ends (the joints), of the bones wear down as a person ages. The disease can damage any joint in the body, but the common ones affected are the hands, lower back, neck, knees, and hips. Symptoms can include sore or stiff joints, stiffness that goes away with exercise, and pain that worsens after activity or toward the end of the day. Results are inconclusive, but some studies indicate that capsaicin may function as a pain reliever for this condition, and it works on osteoarthritis pain by inhibiting a neuropeptide, a nerve chemical, called Substance P that transmits pain from the nerves to the brain. This Substance P can cause swelling in nerve fibers that results in problems such as cluster headaches, migraines, and sinus headaches. Capsaicin, in theory, blocks Substance P from transmitting pain signals between nerves, and the epidermal nerves that are causing the pain degenerate with consistent use of capsaicin, thus relieving and preventing headaches. The chemical in chilies decreases pain from not only arthritis and headaches but also shingles and peripheral diabetic neuropathy, which is a disease causing tingling or numbness in the extremities such as the feet or hands.
Other components of capsaicin’s healing power may come from salicylates, a natural pain-relieving compound similar to that found in aspirin. Furthermore, capsaicin causes vasodilation. The chemical in chilies dilates capillaries (small blood vessels) and quickly stimulates blood flow to injured areas to heal the wounds, while it acts as a nerve blocker to reduce pain. There is scientific doubt about the efficacy of capsaicin as a pain reliever, and a cautionary note about topical capsaicin is necessary. Capsaicin used on the skin can sometimes cause serious burns. It is advised not to use over-the-counter capsaicin on broken or irritated skin. There is also a danger if the person using the topical cream accidentally rubs the cream or lotion in the eyes since corneal erosion and lesions can occur. Topical, long-term capsaicin use has been shown to increase skin carcinogenesis (i.e., skin cancer formation) in test mice treated with a tumor promoter. Such results show that caution is needed when topical applications containing capsaicin are used in the presence of a tumor promoter, such as exposure to sunlight. There is also concern that ingested capsaicin in chili extract can have a promoting effect on the development of stomach and liver tumors. Red chili powder is a possible risk factor for cancer of the oral cavity, pharynx (the tube that connects the mouth and nasal passages with the esophagus), esophagus (the tube that carries food and liquids as well as saliva from the mouth to the stomach), and of the larynx (commonly called the voice box). Hot peppers might be associated with an increased risk of cancer, especially that of the gallbladder (an organ that is used to store bile that is necessary for breaking down fats) and gastric (stomach) cancer. People with coronary or respiratory diseases should use capsaicin lotions, creams, and patches with caution. There have been reported cases of people with cardiac disease having harmful effects from capsaicin use.
Despite the negative effects of capsaicin, there is some evidence that it can help kill prostate cancer, lung cancer, and other cancers including colon adenocarcinoma (cancers that form in mucous-producing tissues), pancreatic cancer, hepatocellular (liver) carcinoma, breast cancer, and others. Capsaicin causes apoptosis, or cell death, in many types of malignant cell lines.
Research into the medical properties of capsaicin use is both troubling and promising. This herb will require further investigation in the future.
See Also: Traditional Medicine: Central America.
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