University Library
  • Login
A gateway to Melbourne's research publications
Minerva Access is the University's Institutional Repository. It aims to collect, preserve, and showcase the intellectual output of staff and students of the University of Melbourne for a global audience.
View Item 
  • Minerva Access
  • Medicine, Dentistry & Health Sciences
  • Melbourne School of Population and Global Health
  • Melbourne School of Population and Global Health - Theses
  • View Item
  • Minerva Access
  • Medicine, Dentistry & Health Sciences
  • Melbourne School of Population and Global Health
  • Melbourne School of Population and Global Health - Theses
  • View Item
JavaScript is disabled for your browser. Some features of this site may not work without it.

    Associations between dietary factors, lung function and bronchial responsiveness in middle-aged and older Australians

    Thumbnail
    Download
    Final thesis file (18.35Mb)

    Citations
    Altmetric
    Author
    Byrne, Stephanie Miriam
    Date
    2020
    Affiliation
    Melbourne School of Population and Global Health
    Metadata
    Show full item record
    Document Type
    PhD thesis
    Access Status
    Open Access
    URI
    http://hdl.handle.net/11343/265152
    Description

    © 2020 Stephanie Miriam Byrne

    Abstract
    Studies of relationships between dietary factors, lung function and bronchial responsiveness (BR) are limited and findings inconsistent. My aim was to investigate these relationships in middle-aged and older adults. A secondary aim was to identify a more suitable statistical method to assess factors associated with BR and compare its findings to those from the common regression model of the log-transformed dose-response slope (logDRS). I used data from two cross-sectional studies – the Tasmanian Longitudinal Health Study (TAHS) 2010 follow-up and the Chronic Obstructive Pulmonary Disease (COPD) Study. The TAHS is a respiratory study of Tasmanian school children born in 1961. In 2010-2012, an asthma and bronchitis enriched subsample completed spirometry, a methacholine challenge and a questionnaire. I used a linear mixed model (LMM) to examine “known” predictors of BR and compared the findings to those from regression of the logDRS. I used multivariable linear regression to investigate associations between fruit and vegetable intakes and lung function and LMMs to examine associations with BR. The COPD study is a population-based cross-sectional study of adults aged 45-69 years living in inner south-east Melbourne. A random subsample completed spirometry, a methacholine challenge, and questionnaires including a semi-quantitative food frequency questionnaire. I derived dietary patterns from nutrient intakes using principal component analysis and calculated an energy-adjusted dietary inflammatory index (E-DII) as a measure of the inflammatory potential of the diet. I examined associations between these dietary factors and lung function and BR using linear regression and LMMs, respectively. I explored sex, BMI, smoking, asthma status and atopy as effect modifiers of these associations. Results from the LMM differed to those from regression of the logDRS. In particular, sex predicted BR in the regression model but not the LMM. I found relationships between several dietary factors and lung function in those with current asthma only. In this group, higher vegetable intake, higher intakes of a “high potassium & magnesium” dietary pattern, indicating a diet high in fruits, vegetables and wholegrains, and higher intakes of a “low calcium & sugars” dietary pattern, indicating a diet high in vegetables and low in sugar and dairy products, were associated with better lung function. A higher E-DII, indicating a more proinflammatory diet high in animal products and low in fruits and vegetables, was associated with poorer lung function. I also found higher fruit intake was associated with increased BR. Conversely, in those with current asthma, higher scores for several dietary patterns were associated with less BR. In conclusion, I demonstrated results from an LMM can differ to those from regression of the logDRS, and recommend using the LMM to investigate factors associated with BR. My findings suggest a diet low in animal products and high in fruit, vegetables and wholegrains may be beneficial for lung function in adults with asthma. Therefore, a dietary modification program in this group may improve lung function and reduce the prevalence and severity of asthma and COPD. However, further studies are needed to establish causality of the diet-lung function associations and clarify relationships with BR.
    Keywords
    fruit; vegetables; bronchial hyperresponsiveness; linear mixed model; diet; nutrition; dietary patterns; dietary inflammatory index; lung function; forced expired volume in one second; forced vital capacity; bronchial responsiveness

    Export Reference in RIS Format     

    Endnote

    • Click on "Export Reference in RIS Format" and choose "open with... Endnote".

    Refworks

    • Click on "Export Reference in RIS Format". Login to Refworks, go to References => Import References


    Collections
    • Minerva Elements Records [52694]
    • Melbourne School of Population and Global Health - Theses [262]
    Minerva AccessDepositing Your Work (for University of Melbourne Staff and Students)NewsFAQs

    BrowseCommunities & CollectionsBy Issue DateAuthorsTitlesSubjectsThis CollectionBy Issue DateAuthorsTitlesSubjects
    My AccountLoginRegister
    StatisticsMost Popular ItemsStatistics by CountryMost Popular Authors