Certain vegetables can help protect against bladder cancer if they are eaten raw, according to new research.

Scientists at Roswell Park Cancer Institute in Buffalo, N.Y., said cruciferous vegetables such as broccoli, cauliflower and cabbage provide the protection.

"People who consume at least three or more servings of cruciferous vegetables a month had about a 40 percent reduction in risk of bladder cancer," said researcher Susan McCann.

Scientists said in a news release, however, than when these same vegetables are cooked, something makes them less effective.

Other cruciferous vegetables include brussels sprouts and mustard and turnip greens.

A news release about the benefit did not say if the 40 percent figure was based on a controlled experiment, or if researchers corrected for other factors such as general diet or lifestyle differences between groups that got cancer and those that did not.