The substance that gives ginger its flavor appears to inhibit the growth of human colorectal cancer cells, according to research at the University of Minnesota's Hormel Institute in Austin, Minn. Working with mice that lack an immune system, research associate professor Ann Bode and her colleagues found slower rates of cancer growth in mice given thrice-weekly feedings of -gingerol - the main active component of ginger. Bode and co-author Zigang Dong, will discuss the work at a meeting of the American Association for Cancer Research in Phoenix. "Plants of the ginger family have been credited with therapeutic and preventive powers and have been reported to have anti-cancer activity," said Bode. "The substance called -gingerol is the main active compound in ginger root and the one that gives ginger its distinctive flavor."
The researchers tested -gingerol's powers by feeding a half milligram to 20 mice three times a week before and after injecting human colorectal tumor cells into their flanks. Control mice were treated the same, except their food contained no -gingerol. Tumors were allowed to grow until they reached a size of one cubic centimeter (0.06 cubic inch), after which the mice were euthanized.
The mice, known as athymic nude mice, are often used in such studies because they provide a living-body environment in which tumors can grow without interference from an immune system.
The first tumors appeared 15 days after the cells were injected. At that time, 13 tumors of measurable size had appeared among the control mice, four among the -gingerol-treated mice. Mice consuming -gingerol lagged in both the number of animals with measurable tumors and the average size of tumors within the group. For example, all the mice in the control group had measurable tumors by the 28th day following injection of the cells. But it wasn't until the 38th day that the -gingerol group reached that milestone--but even then, one mouse still had no measurable tumors. As of the 49th day following injection, all control mice had been euthanized due to tumor sizes of one cubic centimeter. In contrast, 12 of the 20 -gingerol mice were still alive on that day, and their average tumor 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. Because mice were not allowed to live with tumors 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 tumors, but it looks that way," she said.
Preliminary results also suggested that tumors in the control mice had spread, or metastasized, more than tumors in the -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 tumor cells were administered. In their next round of experiments, the researchers plan to feed ginger to mice only after they have grown tumors to a certain size.
"The new experiments should be more clinically relevant," said Bode. "They will get at the question of whether a patient could eat ginger to slow the metast of a nonoperable tumor."