Broccoli and similar vegetables appear to offer special protection from cancer for smokers, researchers reported.

They found that former smokers and, especially, people still smoking heavily got special benefits from eating the vegetables.

“The most significant effect was in heavy smokers,” Li Tang of Roswell Park Cancer Institute in Buffalo, New York, who led the study, said. People who smoked more than 20 cigarettes a day were considered heavy smokers.

Broccoli and other so-called cruciferous vegetables such as cabbage, cauliflower and Brussels sprouts have been known to lower the risk of cancer in general, perhaps through compounds called isothiocyanates.

Dr Tang and colleagues studied 948 cancer patients and 1,743 people being screened for cancer who turned out not to have it.

All answered detailed questionnaires about habits, including their diet and smoking history.

People who ate cruciferous vegetables, especially raw, were between 20 per cent and 55 per cent less likely to have cancer than those who did not or only rarely ate these foods, Dr Tang told a meeting of the American Association for Cancer Research.

The reduction in risk depended on the type of vegetable consumed and the duration and intensity of smoking.

“A significant effect was only observed among the former smokers and current smokers. We didn't see a significant association among never-smokers,” Dr Tang said.

“These findings are not strong enough to make a public health recommendation yet,” she added.

And, she cautioned: “If you smoke long enough, nothing can help.”

Smoking raises the risk of many types of cancer, including lung cancer, head and neck cancer and bladder cancer.

Reuters