Why is it important to improve dietary assessment methods?

Food frequency questionnaires, which measure a person's usual intake over a defined period of time, and 24-hour recalls, in which a person records everything eaten or drunk during the previous 24 hours, are commonly used to collect dietary information. Short screeners, which include just a few questions about consumption of selected items, can be useful in situations that don't require assessment of the total diet or when resources are limited.

Accurately measuring dietary intake through these methods is crucial to understanding the role of diet in causing and preventing chronic diseases such as cancer, heart disease, and diabetes. Dietary recommendations aimed at encouraging people to follow dietary patterns to promote health and reduce disease risks are based in part on information gathered through these means.

The problem is that these dietary assessment instruments are subject to substantial error, both random and systematic. In addition, people don't always report accurately. So, it's important to design these instruments so that they collect the most accurate information possible and to validate them before use. NCI staff used extensive cognitive testing in developing the DHQ and these short screeners so as to make them easier to use and to improve their performance.