A team of US researchers has discovered that an anti-cancer compound present in cruciferous vegetables, such as cabbage, cauliflower and broccoli, also protects rodents from lethal doses of radiation.

The compound, called 3,3′-diindolylmethane, and known more simply as “DIM,” is already shown to be safe in humans, and so the researchers expect it could serve as a shield to protect healthy tissue in human cancer patients from damage by radiation therapy, or lessen its side effects.

The team, from Georgetown University Medical Center (GUMC) in Washington, DC, reports its findings in the latest online issue of the Proceedings of the National Academy of Sciences (PNAS).

One of the researchers, Eliot Rosen, a professor of oncology, biochemistry and cell and molecular biology, and radiation medicine at Georgetown Lombardi Comprehensive Cancer Center, a part of GUMC, says:

“DIM has been studied as a cancer prevention agent for years, but this is the first indication that DIM can also act as a radiation protector.”

For their study, the team exposed rats to lethal doses of gamma rays and then gave some of them a daily injection of DIM for 2 weeks, while leaving the others untreated.

Prof. Rosen, who describes the results as “stunning,” says:

All of the untreated rats died, but well over half of the DIM-treated animals remained alive 30 days after the radiation exposure.”

The team also tested the treatment on mice, with the same results. In addition, they found the treated mice showed less loss of red blood cells, white blood cells and blood platelets, which are typical side effects in cancer patients who have radiation therapy.

The findings suggest DIM could have two uses: it could protect healthy tissue in cancer patients undergoing radiotherapy, and it could also offer protection in the event of a nuclear disaster.

When they treated the rats, the team found it did not matter whether they started the treatment 24 hours before, or 24 hours after radiation exposure, DIM’s protective effect was the same.

Georgetown University has filed a patent for using DIM and DIM-related compounds as protection against radiation.

Grants from the US Public Health Service, the Center for Drug Discovery at Georgetown University, and other Georgetown funding helped finance the study.

In 2006, Prof. Rosen and his team published a study where they showed another compound also found in cruciferous vegetables, called I3C, improves DNA repair in cells, which in turn helps stop them becoming cancerous.