A
clinical trial involving nearly 300 Chinese men and women residing in one of
China’s most polluted regions found that daily consumption of a half cup of
broccoli sprout beverage produced rapid, significant and sustained higher
levels of excretion of benzene, a known human carcinogen, and acrolein, a lung
irritant. Researchers from the Johns Hopkins Bloomberg School of Public Health,
working with colleagues at several U.S. and Chinese institutions, used the
broccoli sprout beverage to provide sulforaphane, a plant compound already
demonstrated to have cancer preventive properties in animal studies. The study
was published in the June 9, 2014 online edition of the journal Cancer
Prevention Research.
“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, an increasing global problem, causes as many as seven million deaths
a year worldwide, according to the World Health Organization, and has in recent
years reached perilous levels in many parts of China. Last year, the
International Agency for Research on Cancer classified air pollution and
particulate matter (PM) from air pollution as carcinogenic to humans. Diets
rich in cruciferous vegetables, of which broccoli is one, 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 expunge these types of the pollutants.
The
12-week trial included 291 participants who live in a rural farming community
in Jiangsu Province, China, approximately 50 miles north of Shanghai, one of
China’s more heavily industrialized regions. 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%) and 229 women (79%) with a median age of 53
(ranging from 21 to 65) years were enrolled in the study. Urine and blood samples
were taken over the course of the trial to measure the fate of the inhaled air
pollutants.
The
research team found that among participants receiving the broccoli sprout
beverage, the rate of excretion of the carcinogen benzene increased 61%
beginning the first day and continuing throughout the 12-week period. In
addition, the rate of excretion of the irritant acrolein, rapidly and durably
increased 23% during the 12-week trial. Secondary analyses by the investigators
indicated that the sulforaphane may be exerting its protective actions by
activating a signaling molecule, NRF2, that elevates the capacity of cells to
adapt to and survive a broad range of environmental toxins. This strategy may
also be effective for some contaminants 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.”
The
clinical trial targeting prevention is notable in that it evaluated a possible
means to reduce the body burden of toxins following unavoidable exposures to
pollutants. The majority of clinical trials involve treatments of diseases that
have already presented or advanced into later stages. Further clinical trials,
to evaluate optimal dosage and frequency of the broccoli sprout beverage, are
planned in the same general region of China.
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