In the March, 2009 issue of Clinical Immunology, researchers from the David Geffen School of Medicine at the University of California, Los Angeles and the U.S. Environmental Protection Agency report that sulforaphane, a compound that occurs in cruciferous vegetables such as broccoli, may help protect against respiratory inflammation and the diseases it causes, including asthma, chronic obstructive pulmonary disease, and allergic rhinitis.
For their study, the team administered doses ranging from 25 to 200 grams of a preparation of broccoli sprouts, which contain high amounts of sulforaphane, or a preparation of alfalfa sprouts, which do not contain significant amounts of the compound, to 65 men and women for three days. Gene expression of phase II antioxidant enzymes was evaluated in nasal passage rinse samples collected before and after treatment. These enzymes, which include glutathione-s-transferase M1, glutathione-s-transferase P1, NADPH quinine oxidoreductase, and hemoxygenase-1, scavenge free radicals which are believed to be the mechanism by which air pollution and ozone cause airway inflammation.
Increases in the expression of antioxidant enzymes were observed among participants who received 100 grams or more broccoli sprouts, while no phase II enzyme induction was observed among those who received alfalfa sprouts. For subjects who received the highest dose of broccoli sprouts, there was a 101 percent increase in glutathione-s-transferase P1 and a 199 percent increase in NADPH quinine oxidoreductase compared to those who received alfalfa sprouts. No significant side effects were observed.
“This is one of the first studies showing that broccoli sprouts — a readily available food source — offered potent biologic effects in stimulating an antioxidant response in humans,” announced lead researcher Marc A. Riedel, who is an assistant professor of clinical immunology and allergy at the David Geffen School of Medicine. “A major advantage of sulforaphane is that it appears to increase a broad array of antioxidant enzymes, which may help the compound’s effectiveness in blocking the harmful effects of air pollution.”
“We found a two- to three-fold increase in antioxidant enzymes in the nasal airway cells of study participants who had eaten a preparation of broccoli sprouts,” Dr Riedl noted. “This strategy may offer protection against inflammatory processes and could lead to potential treatments for a variety of respiratory conditions.”