Researchers led by biochemist Sanjay K. Srivastava studied the effect of capsaicin, the chemical that makes pepper hot, on aggressive cancer cells. Within 38 days of a group of laboratory mice implanted with pancreatic cancer cells, the mice given capsaicin had tumors half the size of the animals given saline solution. Gastrointestinal problems were not seen with the mice being given capsaicin which could have been a problem if we carry this treatment to humans.
In a related study on prostate cancer tumors, mice given capsaicin orally saw their tumors shrink by ¼ in only 4 weeks. This was another powerful study that seemingly verifies findings done by Japanese researchers 5 years ago that capsaicin killed leukemia cells in test tubes.
How capsaicin does its magic is under debate. One group found that it induced apoptosis (suicide) in the cancer cells and another team of researchers found signs that the compound slowed down cell growth and apoptosis. Either way, the old adage of an apple a day keeps the doctor away may need another line; a jalapeño a day may keep cancer away.