A new study indicates that among nearly 300 adults living in one of China’s most polluted areas, drinking a beverage daily made from broccoli sprouts improved the effects of exposure to high levels of pollution. Only a half cup of the beverage daily helped participants quickly excrete benzene, a known human cancer-causing agent, and acrolein, a lung irritant.
The beverage provides a substance called “sulforaphone,” a plant compound already shown to possess cancer-preventing qualities in animal studies, according to researchers from the Johns Hopkins Bloomberg School of Public Health, working with colleagues at several U.S. and Chinese institutions.
“Air pollution is a complex and pervasive public health problem,” notes John Groopman, PhD, Anna M. Baetjer Professor of Environmental Health at the Johns Hopkins Bloomberg School of Public Health and one of the study’s co-authors. “To address this problem comprehensively, in addition to the engineering solutions to reduce regional pollution emissions, we need to translate our basic science into strategies to protect individuals from these exposures. This study supports the development of food-based strategies as part of this overall prevention effort.”
Air pollution causes as many as seven million deaths a year worldwide, according to the World Health Organization. China in particular has the worst air pollution levels in many parts of the country. Air pollution has been classified as a cause for cancer by the WHO’s International Agency for Research on Cancer in Lyon, France.
Diets rich in cruciferous vegetables, such as broccoli, have been found to reduce risk of chronic degenerative diseases, including cancer. Broccoli sprouts are a source of glucoraphanin, a compound that generates sulforaphane when the plant is chewed or the beverage swallowed. It acts to increase enzymes that enhance the body’s capacity to rid itself of air pollutants.
The 12-week study included 291 participants who live in a rural farming community in Jiangsu Province, China, about 50 miles north of Shanghai, one of China’s more heavily industrialized areas. Participants in the control group drank a beverage made of sterilized water, pineapple and lime juice while the beverage for the treatment group additionally contained a dissolved freeze-dried powder made from broccoli sprouts that contained glucoraphanin and sulforaphane.
Sixty-two men (21 percent) and 229 women (79 percent) with a median age of 53 (ranging from 21 to 65) years were enrolled in the study. Researchers took urine and blood samples over the course of the study to measure levels of inhaled air pollutants.
The researchers found that among participants receiving the broccoli sprout beverage, the rate of excretion of the carcinogen benzene increased 61 percent beginning the first day and continuing throughout the 12-week period. In addition, the rate of excretion of the irritant acrolein, rapidly and strongly increased 23 percent during the 12-week trial.
In another analysis, the investigators found that the sulforaphane may be exerting its protective actions by activating a signaling molecule called NRF2, which increases the capacity of cells to adapt to and survive a broad range of environmental toxins. This strategy may also be effective for some pollutants in water and food.
“This study points to a frugal, simple and safe means that can be taken by individuals to possibly reduce some of the long-term health risks associated with air pollution,” notes Thomas Kensler, PhD, professor at the Johns Hopkins Bloomberg School and one of the study’s co-authors. “This while government leaders and policy makers define and implement more effective regulatory policies to improve air quality.”