The compound in broccoli and other Brassica vegetables such as cabbage, kale and Brussels sprouts -- 3,3'-diindolylmethane also known as DIM -- is also effective in augmenting the immune response in mice, said study leader Leonard Bjeldanes.

"We provide clear evidence that DIM is effective in augmenting the immune response for the mice in the study and we know that the immune system is important in defending the body against infections of many kinds and cancer," Bjeldanes said in a statement. "This finding bodes well for DIM as a protective agent against major human maladies."

The study, published in the Journal of Nutritional Biochemistry, found increased blood levels of cytokines -- proteins which help regulate the cells of the immune system -- in mice fed solutions containing doses of DIM.

The study also found DIM doubled the number of white blood cells, or lymphocytes, which help the body fight infections by killing or engulfing pathogens.