Broccoli is already well known as a superfood - it is a highly nutritious vegetable and a potent cancer-fighter. Scientists now believe that it could hold the key to the fight against breast cancer, because it contains a chemical capable of targeting the cells which fuel the growth of tumors.

A component of broccoli called sulforaphane targets and kills cancer stem cells, as well as preventing new tumors from growing, according to researchers at the University of Michigan.

Current chemotherapies do not work against cancer stem cells, which is why cancer recurs and spreads. Researchers believe that eliminating the cancer stem cells is key to controlling cancer.

For the study, scientists tested the effects of sulforaphane in experiments involving mice and cell cultures.

The author of the study said: "Sulforaphane has been studied previously for its effects on cancer, but this study shows that its benefit is in inhibiting the breast cancer stem cells.

"This new insight suggests the potential of sulforaphane or broccoli extract to prevent or treat cancer by targeting the critical cancer stem cells."

Researchers took mice with breast cancer and injected varying concentrations of sulforaphane from the broccoli extract.

They then used several established methods to assess the number of cancer stem cells in the tumors.

These measures showed a marked decrease in the cancer stem cell population after treatment with sulforaphane, with little effect on the normal cells.

Cancer cells from mice treated with sulforaphane were also unable to generate new tumors. The researchers then tested sulforaphane on human breast cancer cell cultures in the lab, finding similar decreases in the cancer stem cells.

Researchers are currently developing a method to extract and preserve sulforaphane.

The concentrations of sulforaphane used in the study were higher than what can be achieved by simply eating broccoli. However, broccoli is a highly valuable addition to the diet because it is an excellent source of Vitamin C and also provides other beneficial nutrients like Vitamin A and folic acid. There are also numerous studies that have linked the sulfur-containing compounds found in broccoli to fighting breast and prostate cancers.

Research Paper Details:

Li Y, Zhang T, Korkaya H, et al. Sulforaphane, a Dietary Component of Broccoli/Broccoli sprouts, Inhibits breast cancer Stem Cells. Clinical cancer Research May 2010 16; 2580.