title: Dietary zinc is associated with a lower incidence of depression: findings from two Australian cohorts.
abstract: BACKGROUND
  Several animal and human studies have shown that zinc plays a role in reducing depression, but there have been no longitudinal studies in both men and women on this topic. The aim of this study was to investigate dietary zinc, and the zinc to iron ratio, as predictors of incident depression in two large longitudinal studies of mid-age and older Australians.
  
  
  METHODS
  Data were self-reported, as part of the Australian Longitudinal Study on Women׳s Health (women aged 50-61 years) and Hunter Community Study (men and women aged 55-85 years). Validated food frequency questionnaires were used to assess dietary intake. Energy-adjusted zinc was ranked using quintiles and predictors of incident depression were examined using multivariate logistic regression.
  
  
  RESULTS
  Both studies showed an inverse association between dietary zinc intake and risk of depression, even after adjusting for potential confounders. Compared to those with the lowest zinc intake those with the highest zinc intake had significantly lower odds of developing depression with a reduction of about 30-50%. There was no association between the zinc to iron ratio and developing depression in either study.
  
  
  CONCLUSIONS
  Dietary assessment was carried out only at baseline and although adjustments were made for all known potential confounders, residual confounding cannot be entirely excluded.
  
  
  CONCLUSIONS
  Low dietary zinc intake is associated with a greater incidence of depression in both men and women, as shown in two prospective cohorts. Further studies into the precise role of zinc compared to other important nutrients from the diet are needed.
authors.affiliation: Centre for Clinical Epidemiology & Biostatistics, School of Medicine & Public Health, University of Newcastle, Australia. Electronic address: Khanrin.vashum@newcastle.edu.au.
authors.forename: Khanrin Phungamla
authors.initials: KP
authors.lastname: Vashum
authors.affiliation: Centre for Clinical Epidemiology & Biostatistics, School of Medicine & Public Health, University of Newcastle, Australia. Electronic address: Mark.mcevoy@newcatle.edu.au.
authors.forename: Mark
authors.initials: M
authors.lastname: McEvoy
authors.affiliation: Centre for Clinical Epidemiology & Biostatistics, School of Medicine & Public Health, University of Newcastle, Australia. Electronic address: Milton.hasnat@newcastle.edu.au.
authors.forename: Abul Hasnat
authors.initials: AH
authors.lastname: Milton
authors.affiliation: Centre for Clinical Epidemiology & Biostatistics, School of Medicine & Public Health, University of Newcastle, Australia. Electronic address: Patrick.mcelduff@newcastle.edu.au.
authors.forename: Patrick
authors.initials: P
authors.lastname: McElduff
authors.affiliation: Centre for Clinical Epidemiology & Biostatistics, School of Medicine & Public Health, University of Newcastle, Australia; Hunter Medical Research Institute, Newcastle, Australia. Electronic address: Alexis.hure@newcastle.edu.au.
authors.forename: Alexis
authors.initials: A
authors.lastname: Hure
authors.affiliation: Research Centre for Gender, Health and Ageing, University of Newcastle, Newcastle, New South Wales, Australia. Electronic address: Julie.byles@newcastle.edu.au.
authors.forename: Julie
authors.initials: J
authors.lastname: Byles
authors.affiliation: Centre for Clinical Epidemiology & Biostatistics, School of Medicine & Public Health, University of Newcastle, Australia; Hunter Medical Research Institute, Newcastle, Australia; Research Centre for Gender, Health and Ageing, University of Newcastle, Newcastle, New South Wales, Australia; Department of General Medicine, John Hunter Hospital, Newcastle, Australia. Electronic address: John.attia@newcastle.edu.au.
authors.forename: John
authors.initials: J
authors.lastname: Attia
mesh_terms: D000368:Aged; D001315:Australia / Q000453:epidemiology; D003863:Depression / Q000453:epidemiology* / Q000517:prevention & control; D003866:Depressive Disorder / Q000453:epidemiology* / Q000517:prevention & control; D005247:Feeding Behavior; D005260:Female; D006801:Humans; D015994:Incidence; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012306:Risk; D057566:Self Report; D015032:Zinc / Q000008:administration & dosage*
chemical_list: D015032:Zinc
keywords: Australia; Cohort; Depression; Diet; Zinc