The same component of jalapeño peppers that makes them burn the tongue also appears to kill prostate cancer cells. Prostate tumours in mice treated with the compound, called capsaicin, shrank to one-fifth the size of those in non-treated mice, found a new study.
To explore capsaicin’s effect, Phillip Koeffler of the Cedars-Sinai Medical Center in Los Angeles, US, and colleagues exposed human prostate cancer cells in a laboratory dish to the natural compound. They found that capsaicin dramatically slowed the proliferation of the cells in the dish.
And this effect increased as the dose of the chilli compound was raised. Three per cent of prostate cancer cells committed “suicide” – programmed cell death – at low concentrations, rising to up to 75% of tumour cells dying at a higher dose.
Koeffler says this is the first experimental evidence supporting the notion that capsaicin stops the growth of prostate cancer cells.
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Human cancer
He believes that capsaicin jump starts a pathway that triggers cell death. Molecular tests suggest that it achieves this by causing a cascade of events inside the cell that inhibits the release of a protein complex called NF-kappa B, which subsequently causes the cell to self-destruct. This is crucial since cancer is characterised by the uncontrolled growth of cells.
The team also found that capsaicin suppressed the growth of human prostate cancer cells by about 80%. These cells were grafted into mice with suppressed immune systems.
But Koeffler says that men concerned about prostate cancer should not interpret these findings as a reason to up their consumption of hot peppers. He stresses that the compound has not been shown to prevent prostate cancer but instead simply slows its growth. And he adds that he hopes to see human trials in the next two years assessing capsaicin’s effect on prostate cancer.
Take a chilli pill
After prostate cancer is surgically removed, it tends to reappear in about a quarter of patients, the researchers note. For this reason, they say that capsaicin may be most effective in slowing cancer’s return instead of stopping it from first developing.
He adds that one also must take dosages into consideration. A 200-pound (90-kilogram) person would have to eat about 10 fresh habañera peppers – one of the hottest chillies around – per week to consume an amount of capsaicin equivalent to the levels received by Koeffler’s mice.
A habañera typically contains 300,000 Scoville units – a scale used to measure the hotness of chillis – making them positively scorching to the mouth in comparison with the more popular jalapeños, which contain roughly 2500 to 5000 Scoville units. For this reason, he says it is unreasonable to imagine anyone eating fresh peppers to prevent the return of prostate cancer: “You would have to take it in pill form.”
Journal reference: Cancer Research (DOI: 10.1158/0008-5472.CAN-05-0087)
![Astronomers have long known that understanding how star clusters come to be is key to unlocking other secrets of galactic evolution. Stars form in clusters, created when clouds of gas collapse under gravity. As more and more stars are born in a collapsing cloud, strong stellar winds, harsh ultraviolet radiation and the supernova explosions of massive stars eventually disperse the cloud, and their light can bear down on other star-forming regions in the galaxy. This process is called stellar feedback, and it means that most of the gas in a galaxy never gets used for star formation. Researching how star clusters develop can answer questions about star formation at a galactic scale. Now, the state of the art has been further developed with both Hubble and Webb working together to provide a broad-spectrum view of thousands of young star clusters. An international team of astronomers has pored over images of four nearby galaxies from the FEAST observing programme (#1783), trying to solve this mystery. Their results show that it is the most massive star clusters that clear away their gaseous shroud the fastest, and begin lighting their galaxy the earliest. The team identified nearly 9000 star clusters in the four galaxies in different evolutionary stages: young clusters just starting to emerge from their natal clouds of gas, clusters that had partially dispersed the gas (both from Webb images), and fully unobstructed clusters visible in optical light (found in Hubble images). With Webb???s ability to peer inside the gas clouds, they were able to then estimate the mass and age of each cluster from its light spectrum. This image shows a section of one of the spiral arms of Messier 51 (M51), one of the four galaxies studied in this work, as seen by Webb???s Near-Infrared Camera (NIRCam). The thick clumps of star-forming gas are shown here in red and orange, representing infrared light emitted by ionised gas, dust grains, and complex molecules such as polycyclic aromatic hydrocarbons (PAHs). Within these gas complexes, each tens or hundreds of light years across, Webb reveals the dense, extremely bright clusters of massive stars that have just recently formed. The countless stars strewn across the arm of the galaxy, many of which would be invisible to our eyes behind layers of dust, are also laid bare in infrared light. [Image description: A large, long portion of one of the spiral arms in galaxy M51. Red-orange, clumpy filaments of gas and dust that stretch in a chain from left to right comprise the arm. Shining cyan bubbles light up parts of the gas clouds from within, and gaps expose bright star clusters in these bubbles as glowing white dots. The whole image is dotted with small stars. A faint blue glow around the arm colours the otherwise dark background.]](https://images.newscientist.com/wp-content/uploads/2026/05/13114322/SEI_296271016.jpg)
