New research out of UCLA finds that a naturally occurring compound found in broccoli and other cruciferous vegetables may help protect against respiratory inflammation that causes conditions like asthma, allergic rhinitis, and chronic obstructive pulmonary disease.
The researchers found that sulforaphane, a chemical in broccoli, triggers an increase of antioxidant enzymes in the human airway that offers protection against the onslaught of free radicals inhaled every day in polluted air, pollen, diesel exhaust, and tobacco smoke. Supercharged forms of oxygen, free radicals can cause oxidative tissue damage, which leads to inflammation and respiratory conditions like asthma.
"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," says principal investigator Marc Riedl, MD, an assistant professor of clinical immunology and allergy at the David Geffen School of Medicine at UCLA.
"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," says Riedl . "This strategy may offer protection against inflammatory processes and could lead to potential treatments for a variety of respiratory conditions."
For the study, 65 volunteers were given varying oral doses of either broccoli or alfalfa sprout preparations for 3 days. Broccoli sprouts are the richest natural source of sulforaphane; the alfalfa sprouts, which do not contain the compound, served as a placebo.
Rinses of nasal passages were collected at the beginning and end of the study to assess the gene expression of antioxidant enzymes in cells of the upper airways. Results showed significant increases of antioxidant enzymes at broccoli sprout doses of 100 gm and higher, compared with the placebo group.
"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," Riedl said.
The research is published in the March edition of the journal Clinical Immunology.