title: Cod liver oil supplement consumption and health: cross-sectional results from the EPIC-Norfolk cohort study.
abstract: Supplement users (SU) make healthy lifestyle choices; on the other hand, SU report more medical conditions. We hypothesised that cod liver oil (CLO) consumers are similar to non-supplement users, since CLO use might originate from historical motives, i.e., rickets prevention, and not health consciousness. CLO consumers were studied in order to identify possible confounders, such as confounding by indication. The European Prospective Investigation into Cancer (EPIC) investigates causes of chronic disease. The participants were 25,639 men and women, aged 40-79 years, recruited from general practices in Norfolk, East-Anglia (UK). Participants completed questionnaires and a health examination between 1993 and 1998. Supplement use was measured using 7-day diet diaries. CLO was the most common supplement used, more prevalent among women and associated with not smoking, higher physical activity level and more favourable eating habits. SU had a higher occurrence of benign growths and bone-related diseases, but CLO was negatively associated with cardiovascular-related conditions. Although the results of SU characteristics in EPIC-Norfolk are comparable with studies worldwide, the CLO group is different from SU in general. Confounding by indication takes place and will need to be taken into account when analysing prospective associations of CLO use with fracture risk and cardiovascular diseases.
authors.affiliation: Department of Public Health and Primary Care, Strangeways Research Laboratories, University of Cambridge, 2 Worts Causeway, Cambridge CB1 8RN, UK. marleen.lentjes@phpc.cam.ac.uk.
authors.forename: Marleen A H
authors.initials: MA
authors.lastname: Lentjes
authors.affiliation: Department of Population Health and Primary Care, Norwich Medical School, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK. a.welch@uea.ac.uk.
authors.forename: Ailsa A
authors.initials: AA
authors.lastname: Welch
authors.affiliation: Department of Public Health and Primary Care, Strangeways Research Laboratories, University of Cambridge, 2 Worts Causeway, Cambridge CB1 8RN, UK. angela.mulligan@phpc.cam.ac.uk.
authors.forename: Angela A
authors.initials: AA
authors.lastname: Mulligan
authors.affiliation: Department of Public Health and Primary Care, Strangeways Research Laboratories, University of Cambridge, 2 Worts Causeway, Cambridge CB1 8RN, UK. robert.luben@phpc.cam.ac.uk.
authors.forename: Robert N
authors.initials: RN
authors.lastname: Luben
authors.affiliation: Medical Research Council, Epidemiology Unit, Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge CB2 0QQ, UK. nick.wareham@mrc-epid.cam.ac.uk.
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Wareham
authors.affiliation: Clinical Gerontology Unit, School of Clinical Medicine, University of Cambridge, Addenbrooke's Hospital, Cambridge CB2 2QQ, UK. kk101@medschl.cam.ac.uk.
authors.forename: Kay-Tee
authors.initials: KT
authors.lastname: Khaw
mesh_terms: D000367:Age Factors; D000368:Aged; D003060:Cod Liver Oil / Q000008:administration & dosage*; D015331:Cohort Studies; D015986:Confounding Factors, Epidemiologic; D003430:Cross-Sectional Studies; D004034:Diet Surveys / Q000706:statistics & numerical data; D019587:Dietary Supplements / Q000706:statistics & numerical data*; D005247:Feeding Behavior; D005260:Female; D006801:Humans; D008019:Life Style; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D012737:Sex Factors; D012907:Smoking; D011795:Surveys and Questionnaires
chemical_list: D003060:Cod Liver Oil