Food
Because of the burning sensation caused by capsaicin when it comes in contact with mucous membranes, it is commonly used in food products to give them added spice or "heat" (pungency). In high concentrations capsaicin will also cause a burning effect on other sensitive areas of skin. The degree of heat found within a food is often measured on the Scoville scale.Cold milk is the most effective solution against the burning sensation (due to caseins having a detergent effect on capsaicin) and cold sugar solution (10%) at 20°C/68°F is almost as effective. The burning sensation will slowly fade away in about 6–8 hours (maximum) if no actions are taken.
It is common for people to experience pleasurable and even euphoriant effects from eating capsaicin-flavored foods. Folklore among self-described "chiliheads" attributes this to pain-stimulated release of endorphins, a different mechanism from the local receptor overload that makes capsaicin effective as a topical analgesic. In support of this theory, there is some evidence that the effect can be blocked by naloxone and other compounds that compete for receptor sites with endorphins and opiates.
Medical
Capsaicin is currently used in topical ointments, as well as a high-dose dermal patch (trade name Qutenza, one 30- to 60-minute-application every 90 days), to relieve the pain of peripheral neuropathy such as post-herpetic neuralgia caused by shingles. It may be used in concentrations of between 0.025% and 0.075%. It may be used as a cream for the temporary relief of minor aches and pains of muscles and joints associated with arthritis, simple backache, strains and sprains, often in compounds with other rubefacients. The treatment typically involves the application of a topical anesthetic until the area is numb. Then the capsaicin is applied by a therapist wearing rubber gloves and a face mask. The capsaicin remains on the skin until the patient starts to feel the "heat", at which point it is promptly removed. Capsaicin is also available in large bandages that can be applied to the back.Capsaicin creams are used to treat psoriasis as an effective way to reduce itching and inflammation.
According to animal and human studies, the oral intake of capsaicin may increase the production of heat by the body for a short time. Due to the effect on the carbohydrates breakdown after a meal, cayenne may also be used to regulate blood sugar levels. Further research is required to see if capsaicin would be useful to treat obesity.
In 1997, a research team led by David Julius of UCSF showed that capsaicin selectively binds to a protein known as TRPV1 that resides on the membranes of pain and heat sensing neurons. TRPV1 is a heat activated calcium channel, which opens between 37 and 45 °C. When capsaicin binds to TRPV1, it causes the channel to open below 37 °C (normal human body temperature), which is why capsaicin is linked to the sensation of heat. Prolonged activation of these neurons by capsaicin depletes presynaptic substance P, one of the body's neurotransmitters for pain and heat. Neurons that do not contain TRPV1 are unaffected.
The result appears to be that the chemical mimics a burning sensation, the nerves are overwhelmed by the influx, and are unable to report pain for an extended period of time. With chronic exposure to capsaicin, neurons are depleted of neurotransmitters, leading to reduction in sensation of pain and blockade of neurogenic inflammation. If capsaicin is removed, the neurons recover.
Capsaicin is being explored as a possible prophylaxis for Type 1 diabetes by researchers in Toronto, Canada; capsaicin was injected subcutaneously affecting pancreatic sensory nerves of mice with Type 1 diabetes because of a suspected link between the nerves and diabetes.
The American Association for Cancer Research reports studies suggesting capsaicin is able to kill prostate cancer cells by causing them to undergo apoptosis. The studies were performed on tumors formed by human prostate cancer cell cultures grown in mouse models, and showed tumors treated with capsaicin were about one-fifth the size of the untreated tumors. There have been several clinical studies conducted in Japan and China that showed natural capsaicin directly inhibits the growth of leukemic cells.
Another study carried out at the University of Nottingham suggests capsaicin is able to trigger apoptosis in human lung cancer cells as well.
Capsaicin is also the key ingredient in the experimental drug Adlea, which is in Phase 2 trials as a long-acting analgesic to treat post-surgical and osteoarthritis pain for weeks to months after a single injection to the site of pain. More over, it reduces pain resulted rheumatoid arthritis as well as joint or muscle pain from fibromyalgia or other causes.
Other uses
Capsaicin may help treat ear infections such as otitis. There is some evidence that capsaicin may help treat heartburn and circulatory problems such as heart disease from atherosclerosis or plaque that block the arteries to the heart. Capsaicin may also help in reducing risks of arrhythmia.Proposed drug abuse deterrent
Clifford Woolf, the Richard J. Kitz Professor of Anesthesia Research at Harvard Medical School, has suggested using capsaicin to deter abuse of certain extended-release drugs such as OxyContin and Ritalin. When taken as prescribed, opioid prescription drugs such as OxyContin or stimulant drugs such as Adderall XR release their active chemical over time, but when crushed and snorted, taken as a suppository, chewed, or injected, the larger than normal dosage is absorbed all at once and a much stronger effect is produced that can be highly habit forming and dangerous due to the higher risk of overdose. Woolf has argued that adding capsaicin into the capsules would be a safe way to deter abuse. A person taking the capsule in the prescribed way (''i.e.,'' swallowing it whole) would suffer no ill effects from the additive. However, a person crushing it would expose the irritant. Anyone then chewing it, snorting it, or injecting it would be exposed to the full power of the chemical. "Imagine snorting an extract of 50 jalapeño peppers and you get the idea," Woolf said in an interview with the Harvard University Gazette. As of 2006, Woolf's proposal is still in the preliminary stages of development and the additive has not yet entered the production stage.
Less-lethal force
Capsaicin is also the active ingredient in riot control and personal defense pepper spray chemical agents. When the spray comes in contact with skin, especially eyes or mucous membranes, it is very painful, and breathing small particles of it as it disperses can cause breathing difficulty, which serves to discourage assailants. Refer to the Scoville scale for a comparison of pepper spray to other sources of capsaicin.In large quantities, capsaicin can cause death. Symptoms of overdose include difficulty breathing, blue skin, and convulsions. The large amount needed to kill an adult human and the low concentration of capsaicin in chilies make the risk of accidental poisoning by chili consumption negligible.
Pest deterrent
Capsaicin is also used to deter mammalian pests. A common example is the use of ground-up or crushed dried chili pods in birdseed to deter squirrels, since birds are unaffected by capsaicin. Another example is the use of chili peppers by the Elephant Pepper Development Trust to improve crop security for rural communities in Africa.Although hot chili pepper extract is commonly used as a component of household and garden insect repellent formulas, it is not clear that the capsaicinoid elements of the extract are responsible for its repellency.
There are manufacturers that do sell a capsaicin-based gel product that is reported to be a pigeon (feral columbia) deterrent from specific roosting and/loafing areas. Some of these products do have an EPA label and NSF approval.
Equestrian sports
Capsaicin is a banned substance in equestrian sports because of its hypersensitizing and pain relieving properties. At the show jumping events of the 2008 Summer Olympics, four horses tested positive for the substance, resulting in disqualification.Adapted from the Wikipedia article Capsaicin, under the G. N. U. Free Documentation License. Please also see http://en.wikipedia.org/wiki
