"Broccoli and broccoli sprouts kill a bacterium which a lot of us actually have," Jed W. Fahey of the Johns Hopkins University School of Medicine told CBS Radio News. "It doesn't make most of us sick, but some of us it can give ulcers to and eventually lead to stomach cancer."
In laboratory tests the chemical sulforaphane killed helicobacter pylori, a bacteria that causes stomach ulcers and often fatal stomach cancers.
"Sulforaphane does protect against tumors or cancer at multiple organ sites in many animal models," said Fahey. "It looks very much like it is also protective in humans."
And the good news is there appears to be enough of it in broccoli sprouts and some varieties of broccoli to benefit people who eat the vegetables.
The researchers could not say how much broccoli one would have to eat for there to be an impact, something they said could not be determined without long-term tests involving humans.
"The levels were well within the range that you would expect to achieve by eating a serving of broccoli," Fahey said.
The findings are reported in Tuesday's issue of Proceedings of the National Academy of Science. Broccoli sprouts are tiny three-day-old plants that resemble alfalfa sprouts and have a peppery flavor.
"I feel quite comfortable suggesting people eat more fruits and vegetables, specifically cruciferous vegetables, specifically broccoli," Fahey said. "We know it's safe and healthy...we know sulforaphane is effective in protecting against cancers."
Dr. Paul Talalay, a co-researcher at Johns Hopkins, had previously reported sulforaphane is an effective anticancer agent and the new studies extended that work to the bacteria that causes stomach cancer and ulcers.
In the lab, the scientists found that sulforaphane even killed helicobacter that was resistant to commonly used antibiotics.
They also showed it can kill the bacterium whether it's inside or outside cells. In people the bacteria can hide in cells lining the stomach, making it more difficult to get rid of the infection, said Fahey.
While president, George Bush declared he would not eat broccoli, no matter how it was prepared, banned it from Air Force One and told White House chefs not to serve it to him.
"I haven't liked it since I was a little kid and my mother made me eat it," the well-known junk food aficionado told reporters in March 1990. "And I'm president of the United States, and I'm not going to eat any more broccoli."
The more-recent studies concentrated on mice and the researchers will now seek to determine of the same effect occurs in humans.
"If future clinical studies show that a food can relieve or prevent diseases associated with this bacterium in people, it could have significant public health implications in the United States and around the world," Fahey said.
"In some parts of Central and South America, Africa and Asia, as much as 80 percent to 90 percent of the population is infected with helicobacter, likely linked to poverty and conditions of poor sanitation," said Fahey, a plant physiologist.
The bacteria can usually be treated with antibiotics, but these are too costly and scarce in many parts of the world, he noted.
Perhaps "people in some of these very poor areas, where it's almost impossible to even conceive of antibiotic therapy...might, by a relatively minor change in diet, be able to heal themselves," he said.
Dr. Carlos F. Quiros of the University of California, Davis, said he was not surprised by the findings, commenting that many compounds found in vegetables inhibit the growth of pathogens.
Sulforaphane has been shown to have anti-cancer properties, Quiros said, but the amount present varies widely among varieties of broccoli. Quiros, who was not part of Fahey's research group, said he is doing research to develop varieties of broccoli with higher levels of the chemical.
The paper also noted that Fahey, Talalay and Johns Hopkins University own stock in Brassica Protection Products, a company whose mission is to develop chemoprotective food products and which sells broccoli sprouts. Fahey founded the company.
Working with them on the research was a group of scientists from the French National Scientific Research Center led by Alain Lozniewski.