New research findings reveal how this powerful pepper provides pain and itching relief, increases circulation and prevents inflammation. Marilyn Sterling, R.D., reports.
Cayenne's active ingredient is called capsaicin, which stimulates nerve cells in neuron vanilloid receptors—the subject of extensive research since their recent discovery. Vanilloids are a group of compounds that are structurally related to capsaicin. They presumably act on vanilloid receptors. When capsaicin locks into these receptors, it initially causes an increased perception of pain/heat, but upon repeated exposure, the nociceptors (pain detectors), or thermosensitive neurons, are desensitised and cease firing.1
Scientists now believe this process also is the body's danger-sensing mechanism.2 The naturally produced endogenous capsaicin-like substances, the vanilloids, send danger signals when the body experiences injury or intense heat. For example, inflammation stimulates this natural capsaicin, which then triggers pain. Scientists are trying to understand more precisely how vanilloid receptors function in the body—from regulating temperature to preventing pain.
Hot Climates, Hot Foods
When cayenne stimulates the hypothalamus, where body heat is regulated, could it affect body temperature? Researchers are studying the possible correlation between hot climates and the propensity of people who live in them to eat spicy foods. Researchers don't have the definitive answer yet because animal and human experiments yield contrasting results.
In animals, capsaicin simultaneously increases heat production by raising the metabolic rate and increases heat loss by causing the blood vessels to dilate, drawing warm blood toward the skin surface, where heat can dissipate.3
In humans, however, cayenne seems to have the opposite effect. In a recent study, researchers found people given a cayenne supplement before exposure to a temperature of 38°C (100.4°F) had lower skin temperature than those consuming the placebo.4 In another experiment, six young healthy men who ate Tabasco hot sauce with dinner had an elevated body temperature during the first sleep cycle, making it harder for them to fall asleep and to sleep well.5 While cayenne's effect on body temperature is still a mystery, scientific investigations are revealing other secrets.
Cayenne And Circulation
One of cayenne's most remarkable properties is its ability to suppress pathogenic adhesion of clotting cells without interfering with normal blood coagulation. Because clot formation and clumping of clotting cells, or platelets (part of atherogenesis), can lead to stroke and heart attack, many physicians prescribe a daily aspirin to their patients with heart disease to prevent platelet adhesion. However, because aspirin also may inhibit appropriate blood coagulation and increase the risk of hemorrhaging in some patients, taking a baby aspirin daily may be a safer choice. In one study, capsaicin prevented death caused by pulmonary thromboembolism in animals more effectively than aspirin.6
Unlike aspirin, capsaicin decreases the danger of excessive bleeding, and another animal study showed capsaicin reduced bleeding time by 26 percent.7
Animal studies suggest capsaicin helps protect blood vessels in several other ways. It increases heart rate and flow of blood through the heart.8 This powerful spice also dilates and relaxes blood vessel walls.9 Thus, cayenne can increase circulation, carrying more oxygen to all parts of the body.
Peppers And Pain
Researchers are experimenting with capsaicin as a topical pain reliever for a variety of conditions because of its ability to desensitize pain nerves. When hot peppers are applied directly to the skin, there is an initial pain sensation, followed by decreased pain sensitivity. Capsaicin now is being used clinically to treat extreme pain in patients suffering from diabetic neuropathy, HIV, and phantom limb pain.10,11 Numerous over-the-counter topical creams containing capsaicin are effective for treating common pain associated with arthritis, injuries, neck pain and cluster headaches.12
Capsaicin also has been shown to be equally as effective as drugs in relieving itching associated with cirrhosis, injury healing and allergies—economically and with no side effects.13 Cayenne has even been shown to inhibit the itching and pain produced by histamines.14
Cayenne stimulates vanilloid receptors, signaling the brain to release neuropeptides (calcitonin gene-related peptide [CGRP] and substance P), which then travel through the bloodstream and moderate the body's response to environmental stimuli. For example, the vasodilation caused by capsaicin is mediated by CGRP.15 Inflammation and the inflammatory process may be stimulated by substance P, so by stimulating the vanilloid receptors with capsaicin, both the pain and inflammation can be inhibited.
A recent animal study found that stimulating vanilloid receptors with capsaicin in one part of the body can prevent inflammation in another part of the body, possibly by releasing somatostatin, the neurons' anti-inflammatory agent.16 Substance P also catalyzes shock syndrome, and animal studies show cayenne protects against life-threatening shock.17 In the future, it is conceivable that emergency rooms might use cayenne to treat pain and trauma.
Capsaicin is poised to become a dietary supplements best seller, jumping from the frying pan into the medicine cabinet. For those who enjoy hot peppers in their food, it may be just a matter of time before they discover its extensive medicinal and economic value.
Marilyn Sterling, R.D., M.P.H., is a consultant to the natural products industry, a freelance health writer and a clinical nutritionist in Trinidad, California.
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