A study has shown for the first time how sulforaphane, the powerful cancer-fighting agent in found broccoli, is triggered into action by the digestive system, and how the body is able to effectively absorb this beneficial substance to gain considerable anti-cancer benefits from it. Even minimal amounts of this compound - less than a serving a day of broccoli, is enough to have an anti-cancer effect.

Sulforaphane is found not only in broccoli, but in all cruciferous vegetables such as cauliflower, cabbage and Brussels sprouts. It is already known to have anti-cancer and anti-microbial properties, but researchers have wondered exactly how, and how well, the compound is assimilated into the body. According to these findings, this powerful compound is released from its parent compound by bacteria in the lower gut and absorbed into the body, where it provides a direct anti-cancer effect.

"This discovery raises the possibility that we will be able to enhance the activity of these bacteria in the colon, increasing broccoli's cancer-preventive power," one of the researchers said.

"It's also comforting because many people overcook their broccoli, unwittingly destroying the plant enzyme that gives us sulforaphane. Now we know the microbiota in our digestive tract can salvage some of this important cancer-preventive agent even if that happens," they said.

The scientists found for the first time that the intestine was able to perform this important function. They proved it by injecting glucoraphanin, the parent compound for sulforaphane, into the ligated lower gut of rats and demonstrating that sulforaphane is present in blood from the mesenteric vein, which flows from the gut to the liver.

"The presence of sulforaphane in measurable amounts shows that it's being converted in the lower intestine and is available for absorption in the body," they said.

The cecum, the part of the rat's lower gut into which the scientists infused the glucoraphanin, houses bacteria that aid in digestion and metabolism, similar to the human colon.

Sulforaphane is found in high amounts in broccoli and other cruciferous vegetables and it is an extremely potent cancer-fighting agent, so minimal amounts of it are required. One of the researchers explained: "The amount that you get in three to five servings a week - that's less than one daily serving of broccoli - is enough to have an anti-cancer effect. With many of the other bioactive foods you hear about, vast amounts are required for a measurable outcome."

But having a healthy digestive system with well-functioning gut microbiota is vital for obtaining the most benefits from this cancer-fighting compound, which is why the authors stress the importance of eating plenty of prebiotics and probiotics as part of a healthy diet.

"One way (to boost bacteria in the colon and enhance the anti-cancer effects of sulforaphane) might be to feed the desirable bacteria with prebiotics like fiber to encourage their proliferation," they said. "Another way would be to use a probiotic approach - combining, say, broccoli with a yogurt sauce that contains the hydrolyzing bacteria, and in that way boosting your cancer protection."

Research Paper Details

Lai R-H, Miller MJ, Jeffery E. Glucoraphanin hydrolysis by microbiota in the rat cecum results in sulforaphane absorption. Food Funct., 2010.