A study published in the June 9 online edition of Cancer Prevention Research showed that drinking a half-cup of broccoli-sprout beverage turbocharged the body’s ability to rid itself of certain air pollutants. Air pollution is the cause, according to the World Health Organization, of as many as 7 million deaths worldwide every year. Scientists from Johns Hopkins Bloomberg School of Public Health University and Minnesota’s Masonic Cancer Center may have found an inexpensive way to combat these numbers. They performed a trial that included 291 participants from one of China’s most polluted regions, a rural farming community in Jiangsu Province located 40 miles north of Shanghai. The participants, 229 women and 62 men, were between 21 and 65 years of age. For the 12-week study, those in the treatment group drank one half-cup mixture per day of pineapple and lime juice, sterilized water, and freeze-dried broccoli-sprout powder. The control group drank the same daily beverage minus the broccoli-sprout powder. Urine and blood samples were taken throughout the trial.
The researchers monitored the levels of benzene and acrolein that participants excreted. These pollutants were chosen for their molecular stability, which allows them to be more accurately monitored. Benzene, a chemical found in plastics, gasoline, cigarette smoke, and pesticides, has been cited by the U.S. Environmental Protection Agency as a carcinogen. Acrolein, created by burning gasoline, oil, and organic matter, is a toxic respiratory irritant. Within 24 hours of drinking their first broccoli-sprout beverage, participants in the treatment group were excreting 61 percent more benzene than before. This percentage was maintained or increased throughout the trial. The control group’s excretion rate of acrolein increased 23 percent over the 12 weeks of the study.
The key to this boost in the body’s ability to excrete toxic substances is sulfuraphane. The enzyme myrosinase, located both in the plant itself as well as the microflora of the human gut, transforms glucoraphanin into the molecule sulfuraphane when the plant is damaged by, for example, chewing or the digestion process. In experimental models, sulfuraphane has been shown to exhibit anticancer and antimicrobial properties. Glucoraphanin, the precursor to sulfuraphane, is present in high amounts in the sprouts of broccoli. A secondary analysis by the research team says that sulfuraphane’s protective actions may be activating a signaling molecule called NRF2. This signaling molecule increases the ability of human cells to survive and adapt to a wide range of environmental toxins. Thomas Kensler, an author of the study and researcher at both Johns Hopkins and the University of Pittsburgh School of Medicine, said that researchers “wanted to boost the defense mechanism that accelerates the rate that these [substances] are cleared from the body so there is less opportunity for harm to be evoked by chemicals.”
Broccoli sprouts, which are two to four-day-old broccoli seedlings, have a much greater concentration of glucoraphanin than mature broccoli, especially mature broccoli that has been cooked. On the other hand, broccoli sprouts contain about half the vitamin A and one-third the vitamin C of mature broccoli. Rather, it is its anti-cancer, anti-diabetes, and antioxidant-activity phytonutrients that broccoli sprouts are prized for. According to research done over 15 years ago at Johns Hopkins University, three-day-old broccoli sprouts contain as much as 50 times the amount of these phytonutrients than are contained in mature broccoli. Back in the 90s, the university formed a company called Brassica Protection Products and took out a patent on growing broccoli sprouts. Brassica CEO Tony Talalay points out that if people grow broccoli sprouts at home, they are technically “infringing (on our patent).” However, says Talalay, the company does not discourage homesprouters.
That is fortuitous because homesprouting has proved to be an easy and safe way to consume broccoli sprouts. Since 1996 up to the present time, and with the latest incident occurring last month, various salmonella and E. coli food poisoning outbreaks have been traced to raw sprouts. The FDA’s solution is for consumers to thoroughly cook the sprouts that they purchase. Of course, this kills most of the sprouts’ nutrients. The explanation for these outbreaks goes that they are likely contaminated during the seeding process by water runoff from animal production facilities, or manure fertilizer that has been poorly balanced, or unsanitary seed harvesting. As a result of these E. coli and salmonella outbreaks, non-organic sprouts are often rinsed with chlorine to kill bacteria. Luckily, it is quite easy (and inexpensive) to grow one’s own organic broccoli sprouts at home. Experienced homesprouters advise that seeds should be bought from vendors approved by the International Sprout Growers Association (ISGA).
There are a couple of caveats to the Hopkins’ study. The detoxification effect of the broccoli-sprout beverage is only known to extend to pollutants that have been recently encountered. Researchers are not sure if the beverage has any effect on the harmful chemicals that have been in the body a while such as DDT, dioxin, and pesticides that are stored in fat cells. Also, researchers do not yet know how many broccoli sprouts one must consume in order to achieve the most benefit. However, it is important to note that the increased excretion rates of benzene and acrolein did not taper off throughout the study. Kensler said that researchers initially thought the pathway might respond, but that sulfuraphane would wear out its welcome and “the body would tune out.” Kensler noted that only definitive trial will affirm whether rates of disease are decreased when this approach is taken for months or years. For now, Kensler is optimistic that the benefits of broccoli sprouts may extend beyond increasing the body’s ability to excrete benzene and acrolein: “Almost for certain we think that other toxins will be influenced in similar ways.”
By Donna Westlund