A New Study Reveals That Diets Have Slightly Improved Globally Over the Past Three Decades
Most nations would receive a score of around 40.3 on a scale from 0 to 100, where 0 corresponds to a poor diet (think heavy consumption of sugar and processed meats) and 100 to the recommended balance of fruits, vegetables, legumes/nuts, and whole grains. Globally, this represents a modest but significant 1.5-point gain between 1990 and 2018, according to a recent study published in the journal Nature Food by researchers at Tufts University’s Friedman School of Nutrition Science and Policy.
The study, one of the most thorough assessments of the quality of the world’s diet to date—and the first to include findings among children as well as adults—highlights the difficulties faced by governments around the world in promoting healthy eating. Despite modest global gains, there were significant regional differences, with healthy foods becoming more popular in the US, Vietnam, China, and Iran while declining 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 major contributor to illness, accounting for 26% of deaths that could have been avoided globally. Despite the urgent need for interventions and policies to promote healthy eating, little is known about how dietary quality varies by demographics like age, sex, education, and proximity to urban areas—information that could be used to better target public health campaigns.
In order to close this gap, Miller and colleagues used information from over 1,100 surveys from the Global Dietary Database, a sizable, collaborative collection of data on levels of food and nutrient consumption around the world, to measure global, regional, and national eating patterns among adults and children across 185 countries. The Alternative Healthy Eating Index, a validated measure of diet quality, with a 0–100 scale, was the research’s primary outcome.
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 were 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 limitations to consider including 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.
Reference: “Global dietary quality in 185 countries from 1990 to 2018 show wide differences by nation, age, education, and urbanicity” by Victoria Miller, Patrick Webb, Frederick Cudhea, Peilin Shi, Jianyi Zhang, Julia Reedy, Josh Erndt-Marino, Jennifer Coates and Dariush Mozaffarian, 19 September 2022, Nature Food.
DOI: 10.1038/s43016-022-00594-9
The study was funded by the Bill and Melinda Gates Foundation and the American Heart Association.
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“Healthy eating was also influenced by socioeconomic factors, including education level and urbanicity,” says Miller.