title: Opposites don't attract: high spouse concordance for dietary supplement use in the European Prospective Investigation into Cancer in Norfolk (EPIC-Norfolk) cohort study.
abstract: OBJECTIVE
  Dietary supplements are commonly consumed but may not be beneficial for everyone. It is known that supplement users have healthy behaviour characteristics but until now concordance between spouses living in the same household has not been investigated and concordance may be an important behavioural determinant.
  
  
  METHODS
  Prospective cohort study, cross-sectional data analysis.
  
  
  METHODS
  European Prospective Investigation into Cancer in Norfolk (EPIC-Norfolk) in the UK, recruitment between 1993 and 1998.
  
  
  METHODS
  Married (or living as married) participants sharing a household, who attended a health examination and completed a 7 d diet diary were included in the analysis (n 11 060). The age range was 39-79 years.
  
  
  RESULTS
  Nearly 75 % of the households in EPIC-Norfolk were concordant in their supplement use, with 46·7 % not using supplements and 27·0 % using supplements. Concordance increased with age; the percentage of concordant couples varied less by other sociodemographic characteristics. Participants who had a spouse who used a supplement were nearly nine times more likely to use a supplement (unadjusted). Depending on participants' sex and type of supplement used, odds ratios for 'supplement use by spouse' in the prediction of participants' supplement use varied between 6·2 and 11·7 adjusted for participants' age, smoking status, BMI, social class, education level and physical activity.
  
  
  CONCLUSIONS
  'Supplement use by spouse' is an independent and the strongest predictor of participants' supplement use. This phenomenon can be useful in the design of studies and health interventions; or when assessing risk of excessive intake from dietary supplements.
authors: 1University of Cambridge,Department of Public Health and Primary Care, EPIC-Norfolk Study,2 Worts Causeway,Strangeways Research Laboratories,Cambridge CB1 8RN,UK.
authors: Marleen A H
authors: MA
authors: Lentjes
authors: 2University of East Anglia,Norwich Medical School,Department of Population Health and Primary Care,Norwich,UK.
authors: Ailsa A
authors: AA
authors: Welch
authors: 3London School of Hygiene and Tropical Medicine, Department of Medical Statistics and Faculty of Epidemiology and Public Health,London,UK.
authors: Ruth H
authors: RH
authors: Keogh
authors: 1University of Cambridge,Department of Public Health and Primary Care, EPIC-Norfolk Study,2 Worts Causeway,Strangeways Research Laboratories,Cambridge CB1 8RN,UK.
authors: Robert N
authors: RN
authors: Luben
authors: 4University of Cambridge,School of Clinical Medicine,Clinical Gerontology Unit,Cambridge,UK.
authors: Kay-Tee
authors: KT
authors: Khaw
mesh_terms: D000328:Adult; D000368:Aged; D016588:Anticarcinogenic Agents / Q000627:therapeutic use*; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D015930:Diet Records; D019587:Dietary Supplements; D004739:England / Q000453:epidemiology; D005195:Family Relations; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008960:Models, Psychological; D009043:Motor Activity; D009369:Neoplasms / Q000453:epidemiology / Q000517:prevention & control*; D011446:Prospective Studies; D012307:Risk Factors; D012727:Sex Characteristics; D018454:Spouses
chemical_list: D016588:Anticarcinogenic Agents
keywords: Sociodemographic variables