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Defining and Measuring Diet Quality Worldwide
Gallup Blog

Defining and Measuring Diet Quality Worldwide

by Anna Herforth and Andrew Rzepa

Poor diets are the greatest threat to health worldwide. Dietary risks are the no. 1 one risk factor globally for deaths and disability. In fact, poor diets pose a greater risk to health than alcohol, drugs, tobacco and unsafe sex combined.

Malnutrition affects about half the planet, beyond the persistent problems of child undernutrition and nutrient deficiencies. And poor diets are directly responsible for rising obesity rates and are one of the major causes of noncommunicable diseases such as cardiovascular disease, stroke and diabetes.

So it is clear that diet quality has massive implications for public health issues relating to people of all ages, classes and genders in every country and in every part of the globe. It may come as a surprise, then, that we don't actually know what people are eating around the world.

This is because no one is currently collecting systematic data on what people across the planet are eating -- important information to understand dietary trends, inform policy, improve diets and help outcomes worldwide.

First Steps: Scientific Consultation and Consensus

As a first step in pursuing the pioneering idea of measuring diets across countries, the Swiss Agency for Development and Cooperation (SDC) commissioned Gallup to develop a white paper to review definitions of healthy diets and consulted experts to explore what elements of diet should be measured, and how. These experts unanimously agreed on three points. First, the challenge of measuring diet quality has tremendous potential payoff for the global community. Second, a diet quality measure should consist of two key pieces: nutrient adequacy and protection of health. Third, the measure should be the same across cultures and countries to allow comparability, although the questions should be adaptable by country to reflect local foods.

The Gallup and SDC white paper, Seeking Indicators of Healthy Diets, considered international and national dietary recommendations. It concluded that guidelines for healthy diets are all founded on the same general principle -- a healthy diet protects against all forms of malnutrition and noncommunicable diseases.

And while there is no clearly stated, global definition of diet quality, most agree on these two elements: consuming abundant, diverse plant foods, including fruits, vegetables, whole grains, legumes and nuts; and the low consumption of ultraprocessed foods like sugar-sweetened beverages, processed meats and other packaged snack foods.

Additionally, the white paper reviewed expert opinions that diets should contain a minimum level of diversity to meet nutrient needs. Basic dietary diversity, diverse plant foods and ultraprocessed foods are three indicators of diet -- good and bad -- that are universally important across regions and countries, including those that are rapidly transitioning. These indicators provide core measures of diet quality for use in Gallup's proposed commitment to worldwide diet measurement.

Next Steps: Measurement

Given the importance of diet quality to health worldwide, the time has come to measure it. We at Gallup are embarking on a global effort to enable scholars and policymakers to start using cross-country diet-quality monitoring data routinely, filling a decades-old gap in basic information about nutrition.

Gallup's World Poll is uniquely positioned to take on this challenge of monitoring diet quality around the world. Launched in 2005, the World Poll conducts nationally representative surveys in more than 160 countries -- providing a scientific window into the thoughts and behaviors of the world's adult population. This setup allows for comparisons across countries; trends over time; and understanding differences by gender, age and income level, making it an ideal method for supporting the U.N.'s Decade of Action on Nutrition and the monitoring of the Sustainable Development Goals (SDGs).

Taylor Percival contributed to this blog.

Taylor Percival is a Consulting Associate at Gallup.

Learn more about how the Gallup World Poll works.


Dr. Anna Herforth is a Senior Research Associate at Harvard T.H. Chan School of Public Health.
Andrew Rzepa is a Partner at Gallup.

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