Wednesday October 16 2013
Could the humble cabbage protect against radiation?
"The humble cabbage could be the key to protecting people from the side effects of radiotherapy during cancer treatment," the Mail Online reports. The story comes from a study looking at a compound called 3,3'-diindolylmethane, or DIM, which is derived from cruciferous vegetables such as cabbage, broccoli and cauliflower.
Researchers wanted to see if DIM could help protect rats against lethal doses of radiation. They found that irradiated rats injected with DIM survived longer than those left untreated.
This early stage study suggests that DIM might be useful in protecting against the effects of radiation, whether exposure occurs accidentally or during medical treatment.
However, the experiment was performed in rodents. Far more research is required before it is known if similar effects could be achieved in humans.
Radiotherapy is highly effective at controlling several types of cancer, but it can also damage healthy tissue, leading to side effects such as fatigue and sore skin, although most of these are temporary.
This research could be the first step in producing a treatment that provides some protection against these side effects. Until then, we know cabbage is good for you in moderation, but whether it can protect against radiation damage in humans is open to question.
Where did the story come from?
The study was carried out by researchers from Georgetown University and Wayne State University in the US and Soochow University and the Chinese Academy of Medical Sciences, China.
It was funded by the US Public Health Service, the Drug Discovery Program at Georgetown University and a Dean's Pilot Research Award.
The study was published in the peer-reviewed Proceedings of the National Academy of Sciences on an open access basis, so it is free to read online or download.
The Mail's coverage implied that cabbage might protect against the effects of radiation, which is potentially misleading. DIM is in fact derived from a phytochemical in cabbage called I3C.
Researchers injected different doses of DIM into irradiated rats and mice. It is not clear how the doses of DIM used in the study relate to the amount of cabbage a human would have to eat to receive a comparable dosage.
If DIM proved effective against radiation damage in humans, it is likely it would be developed as a medicine.
What kind of research was this?
This was a laboratory study using rats and mice. Its aim was to test whether DIM could protect against the effects of exposure to radiation.
The authors point out that a diet rich in cruciferous vegetables such as cabbage, broccoli and cauliflower is linked to a reduced risk of several human cancers. They say that DIM is already being investigated for its potential to prevent cancer.
What did the research involve?
The researchers conducted a series of experiments in irradiated rats and mice, some of which were injected with DIM and some of which were left untreated.
The researchers used different doses of radiation and various doses of DIM, either before and up to 24 hours after radiation.
The rats were treated with a daily injection of DIM for two weeks. Most injections were into the abdomen, but a further experiment tried injections given just under the skin.
Researchers also implanted human breast cancer cells into mice and irradiated them, with or without DIM injection.
What were the basic results?
The researchers found that rats given the multiple doses of DIM survived longer than untreated rats. This was true whether the treatment started before or up to 24 hours after radiation.
In one experiment, while control animals had died by day 10, up to 60% of treated rats survived 30 days, with the higher doses of DIM resulting in longer survival times.
They also found that about half the rats survived 30 days if a far lower dose of DIM was given before exposure to radiation.
Injecting DIM under the skin appeared to be less effective at protecting the rats against the effects of radiation, with fewer surviving to 30 days.
In the mice implanted with human breast cancer cells, giving DIM did not affect the growth of the tumours, whether they were irradiated or left untreated.
How did the researchers interpret the results?
The researchers say that DIM appeared to work by stimulating repair of the DNA damage caused by radiation and stopping the cell "suicide" that occurs after radiation.
They suggest that DIM could be used by doctors either to reduce radiation sickness in people accidentally exposed to radiation, such as the accident that occurred at the nuclear reactor in Chernobyl, or to prevent or reduce the damage to normal tissue caused by radiotherapy.
The researchers also point out that it is particularly useful that DIM has the ability to protect when given 24 hours after radiation exposure, as access to treatment may be delayed in an accident. They say DIM can be given to humans safely without side effects.
This early stage rodent study suggests that DIM might be useful in protecting against the effects of radiation, whether exposure occurs accidentally or during medical treatment. However, the experiment was performed in rats and mice and it is uncertain whether similar effects could be achieved in humans.
It would be ethically impossible to irradiate humans so the effects of DIM could be tested, although research could be undertaken in patients undergoing radiotherapy for cancer. Far more research is required before DIM could be considered an effective agent against the effects of radiation.
If you have been recommended a course of radiotherapy, bear in mind that while the side effects can be unpleasant, in most cases they will pass once the treatment comes to an end. Thanks to advances in techniques and safety, long-term side effects are now rare.
Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter.