Dietary intake data quality in the clinical research setting: Implications of quality improvement

Food-based randomised controlled trials (RCTs) provide the highest level of evidence on diet-disease relationships, which is used in decision-making for dietary recommendations. Such decision-making processes largely rely on dietary intake data. Thus, high-quality dietary intake data is a prerequisite for better information and decision-making for dietary recommendations. Dietary intake data is generated by the process of collection and coding, emphasising that dietary intake data is generated via a stepwise process. The stepwise process of dietary intake data derivation was used as the conceptual framework for this thesis. Moreover, due to the use of open-ended dietary intake assessment tools in food-based RCTs, dietary intake data coding from dietary intake data source documents (e.g., food records) to the nutrition analysis software is commonly required. Therefore, sources of measurement error may be unique to RCTs. However, little is currently known about the quality of the self reported dietary intake data in food-based RCTs.