Broccoli Sprouts Deter Cancers in Rats

Souped-UpBroccoli, Broccoli Sprouts Deter Cancers in Rats

By Judy McBride
November 15, 2001

USDA ARS

Specially grown broccoli–containing hundreds of times moreselenium than grocery store varieties–protected laboratory rats against mammarytumors in a Roswell Park Cancer Institute laboratory at Buffalo, N.Y.

And high-selenium broccoli sprouts protected rats againstprecancerous lesions in the colon in an Agricultural Research Service laboratoryin Grand Forks, N.D. Whether the findings translate to humans, either forefficacy or safety, will require further study.

John W. Finley, a nutritionist at ARS’ Grand Forks Human NutritionResearch Center, and colleagues recently reported the findings together withClement Ip at Roswell Park, Buffalo; Phil D. Whanger at Oregon State University,Corvallis, and others.

The broccoli heads and sprouts used in these studies were producedfor experimental purposes and are not available commercially. The rats weregiven enough to approximate a human dose of about 200 micrograms daily. Severalhuman studies have shown that taking a 200 mcg-selenium supplement–that’sabout three times the Reference Daily Intake–can reduce the incidence ofseveral types of cancer. But it will not reverse tumors once they develop.

The researchers enriched broccoli because it stores selenium in aunique form, called SeMSC for short. It’s easy for people and animals toconvert SeMSC into the active anticancer agent compared to a much longer processfor other selenium compounds. In earlier studies, when Finley and co-workerschallenged rats with known carcinogens, the animals that had eaten thehigh-selenium broccoli had far fewer precancerous colon lesions than the groupsgiven selenium salts–selenate or selenite.

In the latest studies, Ip and coworkers at the Buffalo lab found asimilar protective effect of high-selenium broccoli against mammary tumors,using a rat model for such tumors. The rats got about 30 times more seleniumfrom the specially grown broccoli than they would in a standard diet.

Meanwhile, Finley and coworkers at the Grand Forks lab testedhigh-selenium broccoli sprouts in a rat model for colon cancer and saw the sameprotective effect they had earlier gotten with high-selenium broccoli. Found inmany health food stores, broccoli sprouts are known to be rich in otheranticancer compounds, but commercially available broccoli sprouts are notenriched in selenium.

ARS is the chief scientific research agency of the U.S. Departmentof Agriculture.