The study was published in the March edition of the journal Clinical Immunology, and showed that the chemical sulforaphane, present in vegetables including broccoli, triggers an increase of antioxidant enzymes in the human airway that offers protection against free radicals that we breathe in every day in polluted air, pollen, diesel exhaust and tobacco smoke. Free radicals can cause oxidative tissue damage, which leads to inflammation and respiratory conditions like asthma, as well as cancer.
Dr. Marc Riedl, the study's principal investigator and an assistant professor of clinical immunology and allergy at UCLA said:
"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,
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.
This strategy may offer protection against inflammatory processes and could lead to potential treatments for a variety of respiratory conditions."
65 volunteers were given varying oral doses of either broccoli or alfalfa sprout preparations for three 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. Researchers found significant increases of antioxidant enzymes at broccoli sprout doses of 100 grams 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," lead author Riedl said.
According to the authors, no serious side effects occurred in study participants receiving broccoli sprouts, demonstrating that this may be an effective, safe antioxidant strategy to help reduce the inflammatory impact of free radicals.
They recommend including broccoli and other cruciferous vegetables as part of a healthy diet.
Details of the study:
Riedl MA, Saxon A, Diaz-Sanchez, D. Oral sulforaphane increases Phase II antioxidant enzymes in the human upper airway, Clinical Immunology, 130 (3), p.244-251, Mar 2009
Adapted from article on Science Daily.
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