If you live in a region with lots of air pollution, you might not always breathe easy. So it might help to sit back, relax and enjoy a helping or two of broccoli.
Better yet, have a stiff cup of broccoli-sprout tea.
It might not be the advice you expect to protect yourself from pollution.
But a study that Thomas Kensler and his team began at Johns Hopkins University and completed at the University of Pittsburgh School of Medicine found that a molecule generated during broccoli consumption, and with higher concentrations found in broccoli-sprout tea, helps purge the body of air-pollution toxins, including carcinogenic benzene. The molecule works rapidly and with staying power.
And neither a broccoli-laden diet nor a gallon of tea is necessary.
A daily cup of the sprout tea or two small helpings totaling 150 grams of broccoli can help rid toxic pollutants from the body, the study found. The vegetable from the cabbage family, often described as a superfood, provides fiber, vitamins K and C and other nutrients, such as the one that eliminates toxins from the body. That's what makes it a widely recommended addition to any diet.
Benzene is a known human carcinogen and lung irritant, according to the study published online recently in the journal Cancer Prevention Research. "Thus, intervention with broccoli sprouts enhances (detoxification) of some airborne pollutants," with expected reductions in health risks from pollution that raises the risk of lung cancer and cardiopulmonary diseases.
The study focuses on the molecule glucoraphanin in broccoli that, when chewed or crushed, produces sulforaphane, which is known to help prevent cancer. Glucoraphanin levels are significantly higher in broccoli stems and seeds than in the mature vegetable itself.
The International Agency for Research on Cancer recently classified air pollution and particulate matter from air pollution as carcinogenic to humans, with outdoor air-pollution levels in China among the world's highest. The research team led by Kensler, who holds a Ph.D. in toxicology and serves as assistant professor at Pitt's medical school, recruited 291 people from a rural area of Qidong in the Yangtze River delta region, 50 miles north of Shanghai, to participate in the study. That region "is the fastest growing economic development area of China," the study says. Pollution levels there are steadily in the unhealthy range with fairly common surges into the very unhealthy and even hazardous range - a pollution level that only rarely occurs nowadays in more polluted areas of the United States.
"Air pollution from expanding industrialization in this region masks the horizon on many days, especially during the winter months. Increases in fossil fuels use in China's industry, transport and residential sectors have resulted in a steep increase in emissions," the study states.
During the 12-week human clinical trial, those in the control group drank a beverage - produced commercially for the study to guarantee dosage levels - comprising bottled water, pineapple and lime juice - while the beverage for the treatment group additionally included a dissolved freeze-dried powder made from broccoli sprouts that contained glucoraphanin and sulforaphane. Urine and blood samples collected throughout the trial were tested to measure and compare air-pollution toxin levels excreted from the bodies of study participants from both groups.
The research team found that those receiving the broccoli-sprout beverage experienced an excretion rate of benzene 61 percent higher than the control group did, beginning the first day of the trial and continuing throughout the 12-week period. The rate of excretion of another airborne pollutant, the nose and throat irritant acrolein, "rapidly and durably" increased 23 percent for the treatment group, compared with the control group, during the course of the trial.
Further analysis by investigators found that sulforaphane may be protective by activating a signaling molecule, NRF2, which elevates a cell's capacity to adapt to and survive a broad range of environmental toxins. "This strategy may also be effective for some contaminants in water and food," the study concludes.
Particulate matter poses significant health risks to the public, especially fine particulates known as PM 2.5, which are so small that they are inhaled deep into the lungs. But a recent European study found that particulate matter, irrespective of particle size, contributes to lung-cancer incidence. Such particles include heavy metals, carcinogenic hydrocarbons and volatile organic chemicals that include benzene and aldehydes, which increase the risk of lung cancer.
Based on the study, broccoli provides a "frugal, simple and safe means" to reduce long-term health risks associated with pollution, the study states. Next the team plans to evaluate optimal dosage levels and consumption frequency of the broccoli sprout beverage in the same region of China.
"Dr. Kensler is a superb scientist and he has strong evidence that broccoli's constituents can help detoxify carcinogens and toxins and enhance their elimination from the body," said Gary Stoner, a professor at the Medical College of Wisconsin whose research focus includes cancer prevention. "This is excellent science."