Guidance for monitoring healthy diets globally

Monitoring of diets is crucial for several reasons. It allows governments and organisations to estimate the prevalence of diet-related health issues, track changes over time, issue early warnings, and design targeted interventions. This report highlights the critical role of healthy diets in preventing malnutrition and non-communicable diseases such as heart disease, diabetes, and diet-related cancers. It emphasises that unhealthy diets are a leading cause of morbidity and mortality globally and aims to provide national and global stakeholders with a standardised approach to measure and monitor the healthiness of diets. This guidance aims to outline the purposes of dietary intake data collection, describe available assessment methods, and guide the selection of appropriate metrics for monitoring healthy diets.

The report stresses that, despite the importance of diet-monitoring data, few countries assess their population’s diets, and there is a lack of dietary indicators in global monitoring frameworks such as the Sustainable Development Goals. The following dietary assessment methods are detailed:
24-hour dietary recall (individuals recall everything they consumed in the past 24 hours), food frequency questionnaire (survey questions ask how often specific foods were consumed over a given period), food records (participants record their food intake in real time, usually over several days), brief dietary assessment instruments or diet screeners (which offer quicker, less detailed assessments, making them suitable for large-scale monitoring), and nutritional biomarkers (biological measurements that reflect dietary intake and nutritional status). Each of these methods has its strengths and weaknesses, with trade-offs between the detail in the information collected and the feasibility of widespread implementation.

The report also introduces the following four key metrics for global monitoring of the healthiness of diets: global diet quality score (measures nutrient adequacy and moderation in diets), global dietary recommendations score (assesses alignment with WHO’s dietary recommendations), minimum dietary diversity for women (a proxy measure of the micronutrient adequacy of women’s diets), and nova ultra-processed food score (evaluates the consumption of ultra-processed foods as a measure of dietary moderation). These four metrics are designed to be easy to measure, analyse, and interpret, providing actionable data for policymakers.

The guidance emphasises the need for countries to routinely collect dietary data, ideally every two to three years. While quantitative dietary surveys provide detailed information, they are resource intensive. Brief dietary assessment instruments offer a more feasible alternative for regular monitoring. The report acknowledges existing gaps in evidence, particularly in the cross-context validity of these metrics, and calls for continued research to refine these tools. Future updates to the guidance will address these gaps and offer more detailed recommendations. In conclusion, this guidance document provides an overview of the range of purposes for measuring the healthiness of diets and explains the dietary assessment methods and types of dietary intake data, surveys, and metrics that are currently available to monitor healthy diets. This document is a first step, and it is intended to be updated and expanded in the next two years.