Scientists found that the compound, called sulforaphane, hindered the growth of human breast cancer cells in the lab. It did so by apparently disrupting the action of protein 'microtubules' within the cells, which are vital for the success of cell division.

The findings are published in the Journal of Nutrition.

Past research has suggested a role for sulforaphane in preventing cancer, possibly due to its effects on detoxification enzymes that can defend against cancer-promoting substances. A study in rats showed that oral sulforaphane blocked the formation of breast tumors, and scientists have found that the chemical can push colon cancer cells to commit suicide.

This latest research suggests a new mechanism -- microtubule disruption -- by which sulforaphane may bestow anti-cancer benefits, according to study co-author Dr. Keith Singletary, a professor of nutrition at the University of Illinois at Urbana-Champaign.

What's "intriguing" about this finding, he told Reuters Health, is that certain cancer drugs work in a similar manner. It's possible that sulforaphane, perhaps in combination with other compounds or drugs, could eventually aid in the prevention or treatment of cancer, according to Singletary.

Whether a diet rich in broccoli and other sulforaphane-containing foods packs enough of the compound to lower cancer risk is unknown. Numerous studies in the general population have linked high vegetable and fruit intake to a lower risk of cancer, including breast cancer -- but zeroing in on which components of these foods may deserve the credit is a tough task.

Much remains to be learned about the chemicals in plant foods, Singletary noted, and scientists generally believe that it's important to get the full complement of nutrients and chemicals in these foods.

"Most people would recommend eating a variety of whole vegetables and fruits," he said.

SOURCE: Journal of Nutrition, September 2004.