Nutrition Users' Guides: an introduction to structured guides to evaluate the nutrition literature.

Despite evidence that nutrition can play a substantial role in curbing the burden of chronic disease, findings reported in the nutrition literature have been plagued with debate and uncertainty, including questions about the confidence we can place in evidence from observational studies, the validity of dietary intake data, and the applicability of randomised trials to real-world patients or members of the public. Structured nutrition users' guides (NUGs) to evaluate common research study designs (ie, randomised trials, cohort studies, systematic reviews and clinical practice guidelines) addressing nutrition questions will help clinicians and their patients, as well as health service workers and policy-makers, use the evidence to make more informed decisions on disease management and prevention. In addition, NUGs will provide comprehensive teaching materials for nutrition trainees on how to appraise, interpret and apply the research evidence. We hereby introduce a series of structured NUGs for the literature on nutrients, foods and dietary patterns and programmes. Each article will address three key components when assessing different study designs used to assess nutrition interventions or exposures, including (1) assessing the methodological quality of the study, (2) interpreting study results (magnitude and precision of treatment or exposure effects for outcomes of benefit and harm) and (3) applying the results to unique patient or population scenarios based on their health-related values and preferences related to the potential benefits, harms, convenience and cost of an intervention. This series of articles will serve to empower clinicians, health service workers and health policy-makers to better understand the validity, interpretability and applicability of the nutrition literature, while also helping practitioners and their clients make more evidence-based, value-sensitive and preference-sensitive nutrition decisions.