The substance that gives ginger its flavour appears to inhibit the growth of human colorectal cancer cells, according to research presented yesterday at a major meeting of cancer experts in the US.
Researchers from the University of Minnesota's Hormel Institute said that they found slower rates of cancer growth in mice without an immune system who were fed [6]-gingerol - the main active component of ginger and the one that gives it its flavour - three times a week.
Research associate professor Ann Bode explained that plants of the ginger family have previously been credited with therapeutic and preventive powers and have been reported to have anti-cancer activity.
The researchers tested [6]-gingerol's powers by feeding a half milligram to 20 mice three times a week before and after injecting human colorectal tumour cells into their flanks. Control mice were treated the same, except their food contained no [6]-gingerol.
Tumours were allowed to grow until they reached a size of one cubic centimeter (0.06 cubic inch), after which the mice were euthanised. The mice, known as athymic nude mice, provide a living-body environment in which tumours can grow without interference from an immune system.
The first tumours appeared 15 days after the cells were injected - 13 among the control mice and four among the [6]-gingerol-treated mice. The [6]-gingerol mice also had on average smaller tumours than the other group.
Even at day 38, one mice in the [6]-gingerol group still had no measurable tumours. At the 49th day following injection, all control mice had been euthanised due to tumour sizes of one cubic centimeter. In contrast, 12 of the 20 [6]-gingerol mice were still alive on that day, and their average tumour size was about 0.5 cubic centimeter, or half the maximum allowable size.
"These results strongly suggest that ginger compounds may be effective chemopreventive and/or chemotherapeutic agents for colorectal carcinomas," said Bode. She added that because mice were not allowed to live with tumours bigger than one cubic centimeter, "it's difficult to know if the ginger-treated mice would have lived longer if left to die of their tumours, but it looks that way."
Preliminary results also suggested that tumours in the control mice had spread, or metastasised, more than tumours in the [6]-gingerol mice, but whether a significant difference actually exists remains to be verified, Bode said.
In these experiments, mice were fed ginger before and after tumour cells were administered. In their next round of experiments, the researchers plan to feed ginger to mice only after they have grown tumours to a certain size.
"The new experiments should be more clinically relevant. They will get at the question of whether a patient could eat ginger to slow the metast of a nonoperable tumour," said Bode.
The University of Minnesota has applied for a patent on the use of [6]-gingerol as an anti-cancer agent, and the technology has been licensed to Pediatric Pharmaceuticals (Iselin, N.J.) The work was supported by the Hormel Foundation and Pediatric Pharmaceuticals.
The work was discussed at the Frontiers in Cancer Prevention Research, a meeting of the American Association for Cancer Research currently taking place in Phoenix, USA.