This week in the journal Cancer Prevention Research, scientists from Johns Hopkins and China's Qidong Liver Cancer Institute report that daily consumption of a half-cup of "broccoli-sprout beverage"—a tea made with broccoli sprouts—produced rapid, sustained, high-level excretion of benzene in research subjects' urine. Their conclusion, building on prior research, is that broccoli helps the human body break down benzene and excrete its byproducts. As benzene is a known human carcinogen commonly found in polluted air in both urban and rural areas, voiding it is an unmitigated virtue.
The broccoli-sprout beverage also increased the levels of the lung irritant acrolein, another common air pollutant, in the subjects' urine.
So every alt-juice shop that sells a $14 broccoli-sprout smoothie on its "cleansing" merits is technically not entirely lying.
The broccoli-sprout beverage is understood to be a vehicle for the compound sulforaphane, which has been shown to have cancer-preventive qualities in animal studies, apparently by activating a molecule called NRF2 that enhances cells' abilities to adapt to environmental toxins. In another study earlier this year, sulforaphane-rich broccoli sprout preparations decreased people's nasal allergic responses to diesel exhaust particles.
The researchers found that among participants who drank the broccoli-sprout beverage, excretion of benzene increased 61 percent—beginning the first day and continuing throughout the 12-week study. Excretion of acrolein increased by 23 percent.
Outdoor air pollution is associated with cardiorespiratory mortality, chronic obstructive pulmonary disease, lung cancer, and overall decreased lung function. According to the World Health Organization, air pollution kills around seven million people every year. It might seem absurd to suggest putting the onus on individual dietary choices, but that's basically what's happening here. Environmental researchers call it chemoprevention. A quarter of the world is breathing unsafe air, and while government officials are hard at work implementing regulatory policies to improve air quality and reduce reliance on fossil fuels, which they surely are, we get to eat more broccoli.
"This study points to a frugal, simple, and safe means that can be taken by individuals," said lead researcher Thomas Kensler, a professor at Johns Hopkins Bloomberg School of Public Health, in a press statement, "to possibly reduce some of the long-term health risks associated with air pollution."
Regular broccoli also contains sulforaphane, though in considerably lower quantities than the sprouts studied here, which the researchers found to be "the maximum tolerated dose."
"The more bitter your broccoli, perhaps the better," Kensler told The Wall Street Journal, adding that one would have to consume roughly 1.5 cups of broccoli every day to get the same amount consumed in this study—even more if it's boiled, which is just no way to prepare broccoli.
Chemoprevention could empower people who live in areas with high levels of air pollution, and this study will provide leverage for broccoli-pushing parents everywhere. "Eat your broccoli, child, or the air will get you. Chemicals that the corporations put in the air will give you cancer. Finish it. The air is coming for you. Finish your broccoli. Eat your broccoli. Don't you. No. Don't you talk to me about policy reform. The only person you can count on in this world is yourself. Swallow. Eat it."