Globally, diets are not much healthier today than they were thirty years ago

On a scale from 0 to 100 of how well people stick to recommended diets, with 0 being a poor diet (think heavy consumption of sugar and processed meats), and 100 representing the recommended balance of fruits, vegetables, legumes/nuts and whole grains, most countries would earn a score around 40.3. Globally, this represents a small, but meaningful, 1.5-point gain between 1990 and 2018, researchers from the Friedman School of Nutrition Science and Policy at Tufts University report today in the journal Nature Food.

The study, one of the most comprehensive estimates yet of global dietary quality—and the first to include findings among children as well as adults—highlights the challenges worldwide to encourage healthy eating. Although global gains were modest, there was notable variation by country, with nutritious options becoming more popular in the United States, Vietnam, China, and Iran, and less so in Tanzania, Nigeria, and Japan.

"Intake of legumes/nuts and non-starchy vegetables increased over time, but overall improvements in dietary quality were offset by increased intake of unhealthy components such as red/processed meat, sugar-sweetened beverages, and sodium," says lead author Victoria Miller, a visiting scientist from McMaster University in Canada who started this study as a postdoctoral scholar with Dariush Mozaffarian, Dean for Policy and Jean Mayer Professor of Nutrition at the Friedman School, and senior author on the paper.

Dietary quality in detail

Poor diet is a leading cause of illness, responsible for 26% of preventable death worldwide. While interventions and policies to support healthy eating are urgently needed, little has been known about differences in dietary quality by demographics such as age, sex, education, or proximity to urban areas—helpful information to target public health campaigns.

Miller and colleagues addressed this gap by measuring global, regional, and national eating patterns among adults and children across 185 countries based on data from over 1,100 surveys from the Global Dietary Database, a large, collaborative compilation of data on food and nutrient consumption levels worldwide. The researchers' primary outcome was the 0 to 100 scale known as the Alternative Healthy Eating Index, a validated measure of diet quality.

Regionally, averages ranged from as low as 30.3 in Latin America and the Caribbean to as high as 45.7 in South Asia. The average score of all 185 countries included in the study was 40.3. Only 10 countries, representing less than 1 percent of the world's population, had scores over 50. The world's highest scoring countries were Vietnam, Iran, Indonesia and India, and the lowest scoring were Brazil, Mexico, the United States and Egypt.

Globally, among adults, women were more likely to eat recommended diets than men, and older adults more so than younger adults.

"Healthy eating was also influenced by socioeconomic factors, including education level and urbanicity," says Miller. "Globally and in most regions, more educated adults and children with more educated parents generally had higher overall dietary quality."

"On average across the world, dietary quality was also greater among younger children but then worsened as children aged," she adds. "This suggests that early childhood is an important time for intervention strategies to encourage the development of healthy food preferences."

The researchers note some study imitations to consider include measurement errors in the dietary data, incomplete survey availability in some countries, and a lack of information on some important dietary considerations, such as trans-fats intake. But the findings offer key benchmarks for comparison as new information is added to the Global Dietary Database.

Turning data into policy

The researchers say that the scale and detail of the Nature Food study enables nutrition researchers, health agencies, and policymakers to better understand trends in dietary intake that can be used to set targets and invest in actions that encourage healthy eating, such as promoting meals made up of produce, seafood, and plant oils.

"We found that both too few healthy foods and too many unhealthy foods were contributing to global challenges in achieving recommended dietary quality," says Mozaffarian. "This suggests that policies that incentivize and reward more healthy foods, such as in healthcare, employer wellness programs, government nutrition programs, and agricultural policies, may have a substantial impact on improving nutrition in the United States and around the world."

The research team next plans to look at estimating how different aspects of poor diets directly contribute to major disease conditions around the world, as well as modeling the effects of various policies and programs to improve diets globally, regionally, and nationally.