Summary: Although consumption of healthier foods like legumes and fruit increased in many places, improvements in overall dietary quality were undermined by rising intake of unhealthy items such as processed meats, sugar-sweetened beverages, and excess sodium.
Source: Tufts University
On a 0 to 100 scale measuring adherence to recommended diets—where 0 represents a very poor diet high in sugar and processed meats, and 100 represents an ideal balance of fruits, vegetables, legumes, nuts, whole grains, and healthy oils—most countries score roughly 40.3.
A global analysis led by researchers at the Friedman School of Nutrition Science and Policy at Tufts University and published in Nature Food finds a modest but meaningful average increase of 1.5 points in that score between 1990 and 2018.
This large-scale study is among the most comprehensive assessments of diet quality to date and is the first to systematically include children as well as adults. It highlights persistent challenges in improving eating patterns worldwide and provides detailed insights for policymakers and health professionals seeking to promote healthier diets.
While some countries showed notable improvements—such as the United States, Vietnam, China, and Iran—others saw little change or declines, including Tanzania, Nigeria, and Japan.
“Intakes of legumes, nuts, and non-starchy vegetables increased in many settings, but these gains were often offset by higher consumption of red and processed meats, sugar-sweetened beverages, and sodium,” says Victoria Miller, the study’s lead author and a visiting scientist from McMaster University who began this work as a postdoctoral scholar at Tufts.
Detailed findings on dietary quality
Poor diet is a leading global cause of illness and contributes to about 26% of preventable deaths worldwide. Yet until now, evidence about how diet quality varies by age, sex, education, and urban versus rural residence has been limited—information that is essential for designing targeted public health interventions.
To address these gaps, the team analyzed more than 1,100 dietary surveys compiled in the Global Dietary Database, estimating diet quality for adults and children across 185 countries from 1990 to 2018. Their primary metric was the Alternative Healthy Eating Index (AHEI), a validated 0–100 measure of overall diet quality.
Regional AHEI averages ranged widely: Latin America and the Caribbean averaged as low as 30.3, while South Asia averaged as high as 45.7. The global mean across all 185 countries was 40.3. Only ten countries—representing under 1% of the global population—recorded scores above 50. Countries with the highest overall scores included Vietnam, Iran, Indonesia, and India; the lowest included Brazil, Mexico, the United States, and Egypt.
Across adults worldwide, women generally scored higher on diet quality than men, and older adults tended to eat closer to recommended patterns than younger adults. Education and urbanicity also mattered: individuals with more education—and children whose parents had more education—typically had better diet quality.
Notably, diet quality was higher among younger children on average but declined as children aged, underscoring early childhood as a critical window for interventions that shape lasting food preferences.
The authors acknowledge limitations, including potential measurement error in dietary surveys, gaps in survey availability for some countries, and lack of data on certain dietary factors such as trans-fat intake. Despite these limitations, the study establishes important benchmarks and a framework to monitor diet quality as new data are added to the Global Dietary Database.
From evidence to policy
Because of its breadth and granularity, this analysis can help nutrition researchers, health agencies, and policymakers identify trends and set priorities. The findings indicate that improving global diet quality will require strategies that both increase access to healthy foods—produce, seafood, legumes, nuts, and healthy plant oils—and reduce incentives for unhealthy options.
“Our results show that insufficient consumption of healthy foods and excessive consumption of unhealthy foods are both driving poor diet quality around the world,” says Dariush Mozaffarian, senior author and Dean for Policy at the Friedman School. “Policymakers can make a significant impact by designing programs—within healthcare, workplaces, government nutrition assistance, and agricultural policy—that reward healthier choices.”
The research team plans follow-up analyses to estimate how specific dietary patterns contribute to major diseases globally and to model the effects of policy and program interventions on diets at global, regional, and national levels.
About this diet and health research news
Author: Press Office
Source: Tufts University
Contact: Press Office – Tufts University
Image: The image is in the public domain
Original Research: Open access. “Global dietary quality in 185 countries from 1990 to 2018 show wide differences by nation, age, education, and urbanicity” by Victoria Miller et al., Nature Food
Abstract
Global dietary quality in 185 countries from 1990 to 2018 show wide differences by nation, age, education, and urbanicity
Reliable, comparable evidence on global dietary patterns—especially for children and adolescents—has been limited, hindering the ability to set targets and prioritize investments that support healthy and sustainable diets. This study quantified diet quality across children and adults by age group, sex, education, and urbanicity in 185 countries between 1990 and 2018 using data from the Global Dietary Database.
The primary outcome was the Alternative Healthy Eating Index (AHEI); the Dietary Approaches to Stop Hypertension (DASH) and Mediterranean Diet Score were assessed secondarily. Overall diet quality remained modest worldwide: in 2018 the mean global AHEI was 40.3 (0 = least healthy, 100 = most healthy), with regional averages ranging from 30.3 in Latin America and the Caribbean to 45.7 in South Asia. Across most regions, children and adults had similar scores, though children scored lower in Central and Eastern Europe and Central Asia, high-income countries, and the Middle East and North Africa. Globally, women and more educated individuals had higher diet quality. Between 1990 and 2018, diet quality improved modestly in most regions but not in South Asia or sub-Saharan Africa.