Q. Are cruciferous vegetables really helpful for fighting cancer?

A. There’s no question that cruciferous vegetables, which include broccoli, cauliflower and brussels sprouts as well as turnips and dark leafy greens like kale and arugula, are good for you. They’re high in fiber, low in calories and rich in nutrients, including vitamins C, E and K, folate and minerals.

Whether eating them also helps prevent cancer is a subject of intense research, said Vandana R. Sheth, a spokeswoman for the Academy of Nutrition and Dietetics.

“While studies in lab animals find significant benefits as far as protecting DNA and anti-inflammatory benefits,” she said, “the results of human studies are mixed.”

All cruciferous vegetables contain glucosinolates, natural substances that break down during chopping, cooking, chewing and digestion into biologically active compounds called isothiocyanates and indoles. In laboratory experiments in rats and mice, these compounds have been found to inhibit cancers of the bladder, breast, colon, liver, lung and stomach. They protect cells from DNA damage by inactivating carcinogens and decreasing inflammation. They can also help inhibit the formation of blood vessels and the migration of tumor cells, processes that help spread cancer.