Background: Dietary assessment is complex, and strategies to select the most appropriate dietary assessment tool
(DAT) in epidemiological research are needed. The DIETary Assessment Tool NETwork (DIET@NET) aimed to establish
expert consensus on Best Practice Guidelines (BPGs) for dietary assessment using self-report.
Methods: The BPGs were developed using the Delphi technique. Two Delphi rounds were conducted. A total of 131
experts were invited, and of these 65 accepted, with 48 completing Delphi round I and 51 completing Delphi round II.
In all, a total of 57 experts from North America, Europe, Asia and Australia commented on the 47 suggested guidelines.
Results: Forty-three guidelines were generated, grouped into the following four stages: Stage I. Define what is to be
measured in terms of dietary intake (what? who? and when?); Stage II. Investigate different types of DATs; Stage III.
Evaluate existing tools to select the most appropriate DAT by evaluating published validation studies; Stage IV. Think
through the implementation of the chosen DAT and consider sources of potential biases.
Conclusions: The Delphi technique consolidated expert views on best practice in assessing dietary intake. The BPGs
provide a valuable guide for health researchers to choose the most appropriate dietary assessment method for their
studies. These guidelines will be accessible through the Nutritools website, www.nutritools.org.