Effect of broccoli sprouts on nasal response to live attenuated influenza virus in smokers: a randomized, double-blind study

PLoS One. 2014 Jun 9;9(6):e98671. doi: 10.1371/journal.pone.0098671. eCollection 2014.


Background: Smokers have increased susceptibility and altered innate host defense responses to influenza virus infection. Broccoli sprouts are a source of the Nrf2 activating agentsulforaphane, and short term ingestion of broccoli sprout homogenates (BSH) has been shown to reduce nasal inflammatory responses to oxidant pollutants.

Objectives: Assess the effects of BSH on nasal cytokines, virus replication, and Nrf2-dependent enzyme expression in smokers and nonsmokers.

Methods: We conducted a randomized, double-blind, placebo-controlled trial comparing the effects of BSH on serially sampled nasal lavage fluid (NLF) cytokines, viral sequence quantity, and Nrf2-dependent enzyme expression in NLF cells and biopsied epithelium. Healthy young adult smokers and nonsmokers ingested BSH or placebo (alfalfa sprout homogenate) for 4 days, designated Days -1, 0, 1, 2. On Day 0 they received standard vaccine dose of live attenuated influenza virus (LAIV) intranasally. Nasal lavage fluids and nasal biopsies were collected serially to assess response to LAIV.

Results: In area under curve analyses, post-LAIV IL-6 responses (P = 0.03) and influenza sequences (P = 0.01) were significantly reduced in NLF from BSH-treated smokers, while

Nad(p)h: quinoneoxidoreductasein NLF cells was significantly increased. In nonsmokers, a similar trend for reduction in virus quantity with BSH did not reach statistical significance.

Conclusions: In smokers, short term ingestion of broccoli sprout homogenates appears to significantly reduce some virus-induced markers of inflammation, as well as reducing virus quantity. Nutritional antioxidant interventions have promise as a safe, low-cost strategy for reducing influenza risk among smokers and other at risk populations.

Trial registration: ClinicalTrials.gov NCT01269723.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Adult
  • Brassica / chemistry*
  • Double-Blind Method
  • Female
  • Gene Expression Regulation / drug effects
  • Heme Oxygenase-1 / genetics
  • Humans
  • Influenza A Virus, H1N1 Subtype / immunology
  • Influenza A Virus, H3N2 Subtype / immunology
  • Influenza Vaccines / immunology*
  • Male
  • NAD(P)H Dehydrogenase (Quinone) / genetics
  • Nasal Lavage Fluid / immunology
  • Nose / drug effects*
  • Nose / immunology
  • Nose / pathology
  • Orthomyxoviridae / immunology*
  • Plant Extracts / pharmacology*
  • Plant Shoots / chemistry*
  • Smoking*
  • Vaccines, Attenuated / immunology


  • Influenza Vaccines
  • Plant Extracts
  • Vaccines, Attenuated
  • HMOX1 protein, human
  • Heme Oxygenase-1
  • NAD(P)H Dehydrogenase (Quinone)
  • NQO1 protein, human

Associated data

  • ClinicalTrials.gov/NCT01269723