title: Dietary intake is associated with respiratory health outcomes and DNA methylation in children with asthma.
abstract: BACKGROUND
  Asthma is an increasingly common chronic disease among children, and data point toward a complex mechanism involving genetic, environmental and epigenetic factors. Epigenetic modifications such as DNA hypo- or hyper-methylation have been shown to occur in response to environmental exposures including dietary nutrients.
  
  
  METHODS
  Within the context of the asthma randomized trial of indoor wood smoke (ARTIS) study, we investigated relationships between diet, asthma health measures, and DNA methylation. Asthma health measures included a quality of life instrument, diurnal peak flow variability (dPFV) and forced expiratory volume in the first second (FEV1). Dietary intake was assessed with a food frequency questionnaire. Methylation levels of LINE-1 repetitive element and two promoter CpG sites for interferon gamma (IFNγ, -186 and -54) from buccal cell DNA were measured using pyrosequencing assays.
  
  
  RESULTS
  Data were collected on 32 children with asthma living in western Montana who were recruited to the ARTIS study. Selenium and several methyl donor dietary nutrients were positively associated with the asthma quality of life measure. Intake of methyl donating nutrients including folate was positively associated LINE-1 methylation and negatively associated with IFNγ CpG-186. Higher levels of LINE-1 methylation were associated with greater dPFV.
  
  
  CONCLUSIONS
  We identified several nutrients that were associated with improved quality of life measures among children with asthma. The IFNγ promoter CpG site -186 but not -54 was associated with the intake of selected dietary nutrients. However, in this small population of children with asthma, the IFNγ promoter CpG sites were not associated with respiratory health measures so it remains unclear through which epigenetic mechanism these nutrients are impacting the quality of life measure. These findings add to the evidence that dietary nutrients, particularly foods containing methyl donors, may be important for epigenetic regulation as it pertains to the control of asthma.Trial registrationClincialTrials.gov NCT00807183. Registered 10 December 2008.
authors.affiliation: School of Public Health, University of Michigan, 1420 Washington Heights, Ann Arbor, MI 48109 USA.
authors.forename: L
authors.initials: L
authors.lastname: Montrose
authors.affiliation: Center for Environmental Health Sciences, University of Montana, 32 Campus Drive-159 Skaggs, Missoula, MT 59812 USA.
authors.forename: T J
authors.initials: TJ
authors.lastname: Ward
authors.affiliation: Center for Environmental Health Sciences, University of Montana, 32 Campus Drive-159 Skaggs, Missoula, MT 59812 USA.
authors.forename: E O
authors.initials: EO
authors.lastname: Semmens
authors.affiliation: Center for Environmental Health Sciences, University of Montana, 32 Campus Drive-159 Skaggs, Missoula, MT 59812 USA.
authors.forename: Y H
authors.initials: YH
authors.lastname: Cho
authors.affiliation: Department of Health and Human Performance, University of Montana, 32 Campus Drive, Missoula, MT 59812 USA.
authors.forename: B
authors.initials: B
authors.lastname: Brown
authors.affiliation: Center for Environmental Health Sciences, University of Montana, 32 Campus Drive-159 Skaggs, Missoula, MT 59812 USA.
authors.forename: C W
authors.initials: CW
authors.lastname: Noonan
keywords: Asthma; Children; Diet; Epigenetics; Methylation; Nutrition; Quality of life; Spirometry