Vegetables like broccoli and cabbage, known as 'cruciferous' vegetables after the cross-shape that their flowers grow in, contain glucosinolate. This is broken down into active sulforaphane compounds when the plant is cut or chewed.
Sulphoraphane was isolated from broccoli by scientists at John Hopkins University in 1992. In 2002, Dr Jed Fahey and his team demonstrated in a mouse model that sulforaphane can inhibit Helicobacter infections and block the formation of gastric tumors.
H. pylori, is known to cause gastritis and is believed to be a major factor in peptic ulcers and stomach cancer. In humans the cells lining the stomach can act as reservoirs of helicobacter, making it more difficult to get rid of the infection. Nonetheless, in all but 15 to 20 percent of cases it can be tackled with antibiotics.
Unfortunately, in parts of the world where H. pylori is most rampant - such as parts of Central and South America, Africa and Asia, where as much as 80 per cent to 90 per cent of the population may be infected - antibiotics are also in short supply.
"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," said Fahey, when his study was published in the Proceedings of the National Academy of Sciences (2002 May 28;99(11):7610-5).
Now, it seems, this hope is a step closer to becoming reality.
The findings of the new study, led by Akinori Yanaka of the University of Tsukuba, were presented yesterday at the American Association for Cancer Research's Frontiers in Cancer Prevention Research meeting in Baltimore.
The study involved 40 people who were infected with H. pylori. Over a two-month period, 20 of them received 100g of two- to three- day old broccoli sprouts with their food each day. At this young age, broccoli sprouts contain the highest concentrations of sulforaphane.
The other 20 received 100g of fresh alfalfa sprouts.
The rationale for testing broccoli sprouts against alfalfa was that the chemical constituents are very similar. However while broccoli sprouts contain 250mg of sulforaphane glucosinolate per 100g, alfalfa sprouts contain neither sulforaphane nor sulforaphane glucosinolate.
Yanaka and his team measured the presence of H. pylori before the intervention and at one and two months after the intervention had begun through urea breath tests and by evaluating H. pylori-specific stool antigen. They measured the level of pepsinogen in the blood to ascertain gastroenteritis and gastric atrophy.
After two months, the broccoli group showed significantly less H. pylori, although the bacterium was not completely eradicated. Participants' pepsinogen were also reduced. In the alfalfa group however, both H. pylori and pepsinogen remained at pre-intervention levels.
Further tests conducted two months after the end of the intervention showed that both H. pylori and pepsinogen returned to their previous levels when participants stopped consuming the broccoli sprouts.
Commenting on the findings, Yamaka said: "Even though we were unable to eradicate H. pylori, to be able suppress it and relieve the accompanying gastritis by means as simple as eating more broccoli sprouts is good news for the many people who are infected."
He concluded that a diet rich in sulforaphane glucosinolate may help protect against gastric cancer, and hypothesized that this is due to the activation of gastric mucosal antioxidant enzymes that can protect the cells from H. pylori-induced DNA damage.