The influence of survey duration on estimates of food intakes and its relevance for public health nutrition and food safety issues

Objective: To examine the influence of food consumption survey duration on estimates of percentage consumers, mean total population intakes and intake s among consumers only and to consider its relevance for public health nutr ition and food safety issues. Design: Prospective food consumption survey. Setting: A multicentre study in five centres in the European Union-Dublin, Ghent, Helsinki, Potsdam and Rome. Subjects: Teenage subjects were recruited through schools: 948 (80%) out of 1180 subjects completed the survey. Interventions: 14-day food diaries were used to collect the food consumptio n data. Results: For mean rotal population intakes. 53% of the foods had slopes sig nificantly different to 0 (P < 0.05). In practical terms (g/day), these dif ferences were small, with 41% of foods having differences of less than or e qual to 1 g/day and a further 35% having differences of 1-5 g/day. Estimate s of percentage consumers based on 3 days and 14 days were 1.9 and 3.6 time s the 1-day estimate, respectively. For 72% of foods, at least 50% of non-c onsumers on day 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. Conclusion: In practical terms, survey duration influences estimates of per centage consumers and intakes among consumers only but nor mean total popul ation intakes. Awareness of this influence is important for improved interp retation of dietary data for epidemiological studies, development of food-b ased dietary guidelines and food chemical intakes Sponsorship: The institute of European Food Studies, a non-profit research organization based in Trinity College Dublin. Descriptors: food consumption: survey duration.