Capsaicin, the substance found in chili peppers that’s responsible for their spicy and pungent flavor, was found to reduce depression symptoms in rats.
Mexican researchers at the University of Colima were interested in studying capsaicin because it is a TRPV1 antagonist. TRPV1 is a channel found in the limbic system which has been associated with mood management. The fact that the researchers hail from a country where the greatest chili consumers in the world live also inspired them to pursue this work.
During experiments, the researchers gave rats varying doses of capsaicin (0.001–0.25 mg/kg) and found that the rodents moved around more during a forced swim test. This is a test commonly used to screen for antidepressant properties — shorter immobility time and longer swim time are both associated with antidepressant properties.
According to the findings published in Physiology & Behavior, rats treated with a combination of very low doses of capsaicin, which were not effective on their own, and a subthreshold dose of amitriptyline (an antidepressant) displayed less immobility than those treated with a maximally effective dose of amitriptyline.
The findings suggest that even very low doses of capsaicin could ease depression symptoms. Apart from its pungent taste, chili is broadly available all over the globe and has far less intense side effects than current antidepressant drugs. For people that find chilis a bit too spicy, there are topical ointments available that contain capsaicin.
Previously, studies established that capsaicin can diminish the production of substance P, which is the chemical responsible for delivering pain signals to the brain. By hindering the transmission of substance P, capsaicin might provide temporary relief from ailments such as diabetic neuropathy, headaches, rheumatoid arthritis, and shingles. Capsaicin is also known to increase brain endorphin levels and — remarkably enough — lifespan.
In the future, the Mexican researchers plan on conducting further research in order to establish whether capsaicin has any effects on depressive symptoms in humans.