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Citing their new "demonstration of principle" study, a Johns Hopkins researcher and an international team of scientists caution that eating sprouts containing sulforaphane did not cure infection by the bacterium Helicobacter pylori (H. pylori). They do not suggest that eating this or any amount of broccoli sprouts will protect anyone from stomach cancer or cure GI diseases.
However, the study does show that eating a daily dose of broccoli sprouts reduced by more than 40 percent the level of HpSA, a highly specific measure of the presence of components of H. pylori shed into the stool of infected people. There was no HpSA level change in control subjects who ate alfalfa sprouts. The HpSA levels returned to pretreatment levels eight weeks after people stopped eating the broccoli sprouts, suggesting that although they reduce H. pylori colonization, they do not eradicate it.
"The highlight of the study is that we identified a food that, if eaten regularly, might potentially have an effect on the cause of a lot of gastric problems and perhaps even ultimately help prevent stomach cancer," says Jed W. Fahey, MS, ScD, an author of the paper who is a nutritional biochemist in the Lewis B. and Dorothy Cullman Cancer Chemoprotection Center at the Johns Hopkins University School of Medicine.
The discovery that sulforaphane is a potent antibiotic against H. pylori was reported in 2002 by Fahey and colleagues at Johns Hopkins. "Broccoli sprouts have a much higher concentration of sulforaphane than mature heads," Fahey explains, adding that further investigation is needed to affirm the results of this clinical trial and move the research forward. The study, published April 6 in Cancer Prevention Research, builds on earlier test-tube and mouse studies at Johns Hopkins and elsewhere about the potential value of sulforaphane, a naturally occurring biochemical found in relative abundance in fresh broccoli sprouts. Sulforaphane appears to trigger cells in the body, including in the gastrointestinal tract, to produce enzymes that protect against oxygen radicals, DNA-damaging chemicals, and inflammation.
In the new report, the team also shows that when H. pylori-infected mice sipped broccoli-sprout smoothies for eight weeks, there was up to a fourfold increase in the activity of two of these key enzymes that protect cells against oxidative damage. In addition, the number of Helicobacter bacteria in the mice's stomachs decreased by almost a hundredfold it did not change in infected control animals that drank plain water. The researchers also noted a greater than 50 percent reduction in inflammation of the primary target of this bacterium – the body of the stomach – in treated mice but not in controls.
In a related experiment, the team fed the same dose of broccoli sprouts for the same amount of time to H. pylori-infected mice that had been genetically engineered to lack the Nrf2 gene that activates protective enzymes. "These knock-out mice didn't respond," Fahey says, which confirms previous findings for a role of Nrf2 in protection against H. pylori-induced inflammation and gastritis.