Ginger and chilli peppers may inhibit the growth of certain cancers, said scientists at a meeting of the American Association for Cancer Research.
"Patients are using natural products either in place of or in conjunction with chemotherapy, and we don't know if they work or how they work. There's no good clinical data," explained J. Rebecca Liu, from the University of Michigan, author of the ginger study.
The rhizome of the ginger plant (Zingiber officinale) is a rich source of antioxidants, including gingerols, shogaols, zingerones and other ketone derivatives. It has long been used as a remedy for nausea, especially associated with morning sickness.
The Michigan scientists studied the effect of gingerol on ovarian cancer cell lines and found that the ginger extract inhibited cancer progression by promoting two types of cell death, apoptosis (programmed cell death) and autophagic cell death (the cells digest themselves).
"Ginger induced cell death in all ovarian cancer cell lines tested," reported Liu and colleagues (abstract number 4510).
Apoptosis is the body's natural mechanism for removing damaged or useless cells, but the mechanism is faulty in cancer cells, leading to continued growth.
Although experts have stressed that stopping the growth of ovarian cancer in a lab experiment is not the same as real humans, the results offer areas of further study against a disease that is diagnosed in almost 200,000 women worldwide every year.
According to the European School on Oncology, the highest rates of ovarian cancer are in the USA and Northern Europe.
"Our preliminary results indicate that ginger is a nutraceutical that may have significant therapeutic benefit for ovarian cancer patients," concluded Liu.
Ginger has been given a class one safety rating by the American Herbal Products Association (AHPA), indicating that a wide dosage range is safe.
Capsaicin, the compound that gives red chilli pepper its characteristic heat, inhibited pancreatic cancer cell growth in mice, said researchers from the University of Pittsburgh (abstract number LB-351).
"In our study, we discovered that capsaicin fed orally to mice with human pancreatic tumours was an extremely effective inhibitor of the cancer cell process, inducing apoptosis in cancer cells," said lead researcher Sanjay Srivastava.
The Pittsburgh researchers fed med with human pancreatic tumours different amounts of capsaicin for three or five days per week, depending on the size of the mouse. When compared to mice receiving only a saline solution (control group) the scientists found that the capsaicin groups all had tumours only half the size of the control group.
They also found that the test mice had increased levels of proteins associated with apoptosis.
Interestingly, the healthy pancreatic cells showed no signs of any negative effects.
Researchers from the University of California, Los Angeles recently reported that the same chilli pepper compound could inhibit the growth of prostate cancer cells in vitro.
Experts warned against upping people's weekly intake of the hottest known chillies, stressing that high intake of hot chillies has been linked with stomach cancers in populations of India and Mexico.