Eat Broccoli, Beat Bacteria: Plant compound kills microbe behind ulcers and a cancer

A chemical that’s abundant in broccoli and certain other vegetables kills ulcer-causing bacteria in the laboratory and inhibits stomach cancer in mice, according to new research. The findings suggest that adding more of the right plants to the diets of people infected with Helicobacter pylori might take a bite out of several stomach disorders.

Among the most prevalent of pathogens in people, H. pylori has been implicated in the development of inflammation, ulcers, and cancers of the stomach (SN: 12/16/00, p. 389: Antibiotics, vitamins stall stomach cancer).

Poor sanitation abets the spread of the bacteria, which infect 70 to 90 percent of the population in some Asian, African, and South American countries.

Antibiotics are currently the best treatment for H. pylori infection, but financial and logistical constraints limit the use of these drugs in many seriously affected countries. Furthermore, the bacteria occasionally evade the drugs by taking refuge inside cells that line the stomach, only to reemerge when treatment ends.

Some H. pylori strains have also developed resistance to certain antibiotics.

To better combat H. pylori, Jed W. Fahey of the Johns Hopkins University School of Medicine in Baltimore and his colleagues there and in Vandoeuvre-les-Nancy, France, look to sulforaphane. This compound, common in cruciferous vegetables such as broccoli, broccoli sprouts, and cauliflower, discourages foraging insects–and picky children–with its pungent taste.

Past research suggested that the compound fights some other harmful microbes and also boosts the production of carcinogen-neutralizing enzymes (SN: 3/24/01, p. 182: Veggies prevent cancer through key protein). The new research indicates that both these actions might fend off stomach disorders.

Fahey and his colleagues first compared the efficacy of sulforaphane to that of three antibiotics currently used to treat H. pylori. In lab conditions intended to simulate the environment inside the stomach, sulforaphane inhibited the proliferation of all 48 strains of bacteria the researchers tested.

The researchers then tested different concentrations of sulforaphane against two of the H. pylori strains. Importantly, Fahey and his colleagues found that sulforaphane killed H. pylori even when the bacteria had taken shelter inside human stomach cells that were growing in flasks.

One strain survived less than a day when exposed to a concentration of at least 2 micrograms per milliliter. The other died off rapidly only at twice that concentration, the researchers report in the May 28 Proceedings of the National Academy of Sciences. People who eat broccoli could achieve similar concentrations in their blood, Fahey says.

In separate experiments, Fahey and his colleagues gave mice a chemical known to produce multiple stomach tumors. Although they were not infected with H. pylori, mice fed a high-sulforaphane diet before, during, and after they were exposed repeatedly to the carcinogen developed only 61 percent as many tumors, on average, as carcinogen-treated mice on a regular diet did. That observation suggests that sulforaphane could fight stomach cancer independently of its effects on Helicobacter infections.

When it comes to battling H. pylori, purified sulforaphane might become a useful weapon, especially against strains that have become resistant to conventional drugs, suggests Leonard Bjeldanes of the University of California, Berkeley.

However, Bjeldanes says, it “remains to be established . . . whether the substance is effective against human infections at concentrations possible from the diet.” He further cautions that excessive intake of sulforaphane-rich vegetables could expose people to toxic compounds, such as pesticides, that those foods might contain.

While broccoli isn’t likely to replace antibiotics in the campaign against H. pylori, dietary changes could help. “People with ulcers could try two or three servings [of cruciferous vegetables] a day prior to going on antibiotic therapy,” Fahey suggests. He and coauthor Paul Talalay, also at Johns Hopkins, own stock in a company that sells broccoli sprouts.