The influence of survey duration on estimates of food intakes - relevance for food-based dietary guidelines

Development of food-based dietary guidelines relies on correct identificati on and interpretation of current dietary intake patterns. The process invol ves assessing Which foods discriminate between those with desirable and und esirable intakes of particular nutrients. It is therefore important that th ose involved in this task are aware of any source of variability in the und erlying food consumption data that cannot be attributed to true differences between individuals. A short survey duration can introduce a high degree o f within-person variation and not reflect usual or more long-term food or n utrient intakes. As survey duration increases, the % consumers identified b y a survey increases and the intakes among consumers only decrease while th e total population intakes do not change. A short survey duration may also lead to misclassification of individuals into high and low consumers. Surve y duration is therefore an issue that should be considered in the interpret ation of dietary data when developing food-based dietary guidelines.