Diet Quality Declines Worldwide, But With Major Differences Across Countries

Data intended to inform dietary policies directed at reducing chronic disease, obesity rates

BOSTON- In a first-of-its-kind analysis of worldwide dietary patterns, a team including researchers from the Friedman School of Nutrition Science and Policy at Tufts University and the Medical Research Council (MRC) Epidemiology Unit, University of Cambridge found overall diet quality worsened across the world even as consumption of healthier foods increased in many countries. The study compared trends in intakes of healthy versus unhealthy foods in 1990 and 2010 and found major differences by country. Overall, increases in unhealthy foods outpaced beneficial dietary changes, especially in middle-income nations. Results were published in the March issue of The Lancet Global Health.

“While it’s encouraging to see some improvement in parts of the world, we still have a long way to go,” said Dariush Mozaffarian, M.D., Dr. P.H., senior author and dean of the Friedman School of Nutrition Science and Policy at Tufts University. “With this analysis, we’re supplying data that support longtime speculation that, globally, our diets are getting worse. We also show that these changes in dietary patterns vary significantly by country: in some countries, lack of healthy foods is the biggest problem; in others, excess unhealthy foods; and in others, such as the United States, it’s both.  This tells us there is no one-size-fits-all approach to improving global diets.”

Mozaffarian is chair of the Global Burden of Diseases Nutrition and Chronic Diseases Expert Group (NutriCoDE), an international team of scientists studying the effects of nutrition on health who contributed to this analysis. They reviewed 325 dietary surveys, representing almost 90 percent of the world’s adult population, focusing on 17 common foods, drinks and nutrients. Included were healthier options such as whole grains, fish, fruits and vegetables, and polyunsaturated fat, and unhealthy options such as sodium, cholesterol, processed meat, and sugar-sweetened beverages.

Internationally, older adults tended to have better quality diets than younger adults, and women tended to eat healthier than men.  The team found important relationships between country income and diet quality.

They saw an increase in consumption of healthy foods and nutrients in high and middle-income countries, but little increase in low-income countries. The authors suggest that the positive changes may be due to better storage, transport and availability of out-of-season foods worldwide; and, in higher income countries, improvements in agricultural practices and increased recognition of the importance of healthier diets to minimize diet-related, non-communicable diseases such as diabetes and cardiovascular disease.

“At the same time, we saw an even stronger association between national incomes and unhealthy diet patterns,” said first author Fumiaki Imamura, Ph.D., a senior investigator scientist at the MRC Epidemiology Unit. “In other words, people in high income countries, and increasingly middle income countries, are among the biggest consumers of unhealthy foods.”

The authors saw no increase in consumption of healthier food items in the world’s poorest regions. “The lack of improvement in areas like Sub Saharan Africa and the Andean States of Latin America underlines the urgent need to address diet quality in the poorest nations, where rises in obesity, diabetes, and cardiovascular diseases are joining undernutrition and nutrient deficiencies as health problems,” said Imamura, who received his Ph.D. from the Friedman School. “If we don’t step up efforts to improve the current food supply, we could see the same turn toward nutrient-poor, processed foods as we’ve seen in China, India and other middle income countries where we saw the largest increases in consumption of unhealthy foods.”  

Although the analysis encompasses global dietary data from individual surveys, the authors acknowledge some study limitations, including a reliance on self-reported dietary questionnaires and less data for some regions, dietary factors and years. Future studies to investigate dietary differences among socioeconomic groups within each country would be beneficial.  

“Poor diet quality is now the number one cause of poor health in the U.S. and the world, causing enormous suffering and costing trillions of dollars,” Mozaffarian said. “These new findings can be used to inform policies and prevention efforts aimed at improving dietary patterns to reduce these burdens.”  

This work was supported by a by a grant to Mozaffarian from the Bill and Melinda Gates Foundation.  Imamura also received support from the Medical Research Council Epidemiology Unit Core Support (MC_UU_12015/5). The paper provides additional financial information.

Imamura F, Micha R, Khatibzadeh S, Fahimi S, Shi P, Powles J, and Mozaffarian D on behalf of the Global Burden of Disease Nutrition and Chronic Diseases Expert Group (NutriCoDE). “Dietary quality among men and women in 187 countries in 1990 and 2010”. The Lancet Global Health.  March 2015.

About the Friedman School of Nutrition Science and Policy

The Gerald J. and Dorothy R. Friedman School of Nutrition Science and Policy at Tufts University is the only independent school of nutrition in the United States. The school's eight degree programs – which focus on questions relating to nutrition and chronic diseases, molecular nutrition, agriculture and sustainability, food security, humanitarian assistance, public health nutrition, and food policy and economics – are renowned for the application of scientific research to national and international policy.


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