title: The influence of survey duration on estimates of food intakes and its relevance for public health nutrition and food safety issues.
abstract: OBJECTIVE
  To examine the influence of food consumption survey duration on estimates of percentage consumers, mean total population intakes and intakes among consumers only and to consider its relevance for public health nutrition and food safety issues.
  
  
  METHODS
  Prospective food consumption survey.
  
  
  METHODS
  A multicentre study in five centres in the European Union-Dublin, Ghent, Helsinki, Potsdam and Rome.
  
  
  METHODS
  Teenage subjects were recruited through schools; 948 (80%) out of 1180 subjects completed the survey.
  
  
  METHODS
  14-day food diaries were used to collect the food consumption data.
  
  
  RESULTS
  For mean total population intakes, 53% of the foods had slopes significantly different to 0 (P<0.05). In practical terms (g/day), these differences were small, with 41% of foods having differences of </=1 g/day and a further 35% having differences of 1-5 g/day. Estimates of percentage consumers based on 3 days and 14 days were 1.9 and 3.6 times the 1-day estimate, respectively. For 72% of foods, at least 50% of non-consumers on day 1 became consumers over the subsequent 13 days. Estimates of mean consumer only intakes based on 3 days and 14 days were 53% and 32% of the 1 day value.
  
  
  CONCLUSIONS
  In practical terms, survey duration influences estimates of percentage consumers and intakes among consumers only but not mean total population intakes. Awareness of this influence is important for improved interpretation of dietary data for epidemiological studies, development of food-based dietary guidelines and food chemical intakes.
  
  
  BACKGROUND
  The Institute of European Food Studies, a non-profit research organization based in Trinity College Dublin. European Journal of Clinical Nutrition (2000) 54, 166-173
authors.affiliation: Institute of European Food Studies, Biotechnology Institute, Trinity College, Dublin 2, Ireland. iefs@iefs.ie
authors.forename: J
authors.initials: J
authors.lastname: Lambe
authors.forename: J
authors.initials: J
authors.lastname: Kearney
authors.forename: C
authors.initials: C
authors.lastname: Leclercq
authors.forename: H F
authors.initials: HF
authors.lastname: Zunft
authors.forename: S
authors.initials: S
authors.lastname: De Henauw
authors.forename: C J
authors.initials: CJ
authors.lastname: Lamberg-Allardt
authors.forename: A
authors.initials: A
authors.lastname: Dunne
authors.forename: M J
authors.initials: MJ
authors.lastname: Gibney
mesh_terms: D000293:Adolescent; D015992:Body Mass Index; D002648:Child; D015930:Diet Records; D004034:Diet Surveys; D002149:Energy Intake; D005060:Europe; D005260:Female; D005502:Food; D006801:Humans; D008297:Male; D009747:Nutritional Physiological Phenomena; D011446:Prospective Studies; D011634:Public Health; D012449:Safety; D013997:Time Factors