Researchers at Ohio State University reported at the recent IFT show in New Orleans that isothiocyanates hindered the growth of bladder cancer cells in the lab, with the most profound effect on the most aggressive form of bladder cancer they studied.
The findings build on a major study conducted six years ago by Harvard and Ohio State universities that found that men who ate two or more half-cup servings of broccoli per week had a 44 per cent lower incidence of bladder cancer compared to men who ate less than one serving each week.
In the UK, bladder cancer is the fifth most common cancer, while in the US, some 63,000 people will be diagnosed with the disease this year, according to the American Cancer Society. More than 13,000 of these will die.
Steven Schwartz, a professor of food science and technology at Ohio State University, and colleagues isolated compounds called glucosinolates from broccoli sprouts.
During chopping, chewing and digestion, these phytochemicals morph into isothiocyanates - the anti-cancer compounds - but the scientists used an enzymatic process to convert the glucosinolates to isothiocyanates.
They then treated two human bladder cancer cell lines and one mouse cell line with varying amounts of glucosinolates and isothiocyanates. Even though glucosinolates are converted to isothiocyanates, the researchers wanted to know if the former would have any effect on controlling the growth of cancer cells.
The isothiocyanates decreased proliferation in all three cell lines. The strongest effect was on the most aggressive of these lines - human invasive transitional cell carcinoma.
The glucosinolates had no such effect.
The researchers are now investigating the mechanism for this anti-cancer action.
"We're now studying more of those compounds to determine if they work together or independently, and what kind of effects they have on cancer cells," said Steven Clinton, a study co-author and an associate professor of haematology and oncology at Ohio State.
He added: "There's no reason to believe that this is the only compound in broccoli that has an anti-cancer effect. There are at least a dozen interesting compounds in the vegetable."