In nutritional epidemiology, development of valid dietary assessment instruments specific to populations in diverse settings is of paramount importance. Such instruments are essential when trying to characterise dietary patterns and intake, investigate diet-disease associations, inform and evaluate nutrition interventions, assess nutrient-gene interactions, conduct cross-country comparison studies and monitor nutrition transitions. The FFQ is a relatively inexpensive tool for measuring long-term dietary intake for large populations and for allowing researchers to track dietary changes over time. However, FFQ must be population specific to capture the local diet and available foods. Collecting 24-h dietary recalls and utilising community feedback to build the FFQ ensures that a culturally appropriate instrument is developed. This article presents several examples describing FFQ development and utilisation in different settings globally. In the Canadian Arctic, FFQ were developed and utilised to inform and evaluate a communitybased intervention programme, characterise the diet and track dietary changes occurring among Inuit and Inuvialuit, populations experiencing rising rates of chronic disease and likely to be extremely vulnerable to the potential effects of climate change. Another example is an FFQ developed to assess sodium intake and evaluate a sodium reduction trial in a high-risk population in Barbados. An example is provided from Brazil, where an FFQ was developed to assess associations between diet, heterocyclic aromatic amines and colorectal adenoma among Japanese Brazilians and to conduct cross-country comparisons. These and other case studies highlight the diversity in dietary intake between populations and the need for FFQ to be developed to capture this diversity.
FFQ: Nutritional epidemiology: Interventions: Multi-ethnic populations
Dietary assessment methodologiesIn nutritional epidemiology, a variety of different approaches can be used to measure food and nutrient intakes in individuals and populations. These range from relatively simple techniques such as 24-h dietary recalls, estimated or weighed food records, narrative diet histories and FFQ, to the more complex biochemical approach of measuring static or functional markers of nutrient intake in blood, urine or other biological samples. The selection of a dietary assessment methodology depends on the population under investigation and typically involves a compromise between the desired level of accuracy and organisational or financial constraints (1) . Biochemical markers of nutrient intake, while arguably more objective than other methods, are used infrequently outside of small validation or pilot studies due to their high cost and logistical requirements (2) . Food records and 24-h dietary recalls are expensive and