Over the past thirty years, our diet hasn't improved

By Dr. Liji Thomas, MDSep 22 2022Reviewed by Benedette Cuffari, M.Sc.

Everybody eats; however, the way in which people eat differs on their culture, geography, level of knowledge, and economic status. Moreover, diet is linked to many diseases, with poor diet quality responsible for over 25% of preventable global deaths.

A new Nature Food study describes diet quality on a global basis in a stratified manner. Herein, researchers report modest diet quality in all regions, with small gains reported in most regions, except for South Asia and sub-Saharan Africa.

Study: Global dietary quality in 185 countries from 1990 to 2018 shows wide differences by nation, age, education, and urbanicity. Image Credit: Akhenaton Images / Shutterstock.com

Introduction

The greatest dietary benefit is observed when food and nutrients are consumed together in a complementary fashion. Although the components of an optimal diet have been well established, the global eating patterns remain nebulous. A poor diet can cause growth retardation, increased cardiometabolic risk, and poor health among children.

Previous research on dietary quality has been limited, as these studies largely exclude children and adolescents. Furthermore, many of these studies used limited data on food consumption and sociodemographic characteristics such as age, sex, education, and residential area.

The current sizeable multinational study uses three different diet quality scores to assess global eating patterns at the individual level.

About the study

The data used in this study was obtained from the last Global Dietary Database (GDD) compiled in 2018. This collaborative database is formed from the systematic and standardized compilation of data on 53 foods, nutrients, and beverages.

Data were acquired from surveys carried out in 185 countries between 1990 and 2018. All data were analyzed by age, sex, education, and urban-dwelling status.

Assessment of diet quality was performed primarily using the Alternative Healthy Eating Index (AHEI), with secondary comparative analyses using the Dietary Approaches to Stop Hypertension (DASH) and Mediterranean Diet Score (MED).

AHEI scores are associated with reductions in the risk of cardiovascular disease (CVD), diabetes, and cancer by almost 25%, 30%, and 5%, respectively. Conversely, an increase in AHEI scored by just 20% improves the risk of death from CVD or cancer. This underlines the importance of the current study, with actionable findings that should prompt corrective steps to enhance the quality of diet and thus reduce diet-related morbidity and mortality over the next few years.

Study findings

With a potential maximum of 100, the average global AHEI score was 40 in 2018. Only ten countries that comprise less than 1% of the world’s population surpassed a score of 50.

When densely populated countries were assessed, Vietnam, Iran, Indonesia, and India had the highest scores, all of which were around 50. In contrast, the United States, Brazil, Mexico, and Egypt had lower scores than 30.

The range extended from 30 in Latin America and Caribbean countries to almost 49 in South Asia. Legumes and nuts had the highest global score, followed by whole grains.

Non-starchy vegetables and seafood rich in omega-3 fat also had relatively good AHEI scores. Overall, the highest scores were for sugar-sweetened beverages (SSBs) and red and processed meat.

Individual diet components like sodium and meat differed 100-fold between populous countries, while SSBs exhibited a 23-fold difference. On the other hand, the intake of polyunsaturated fatty acids (PUFAs) and non-starchy vegetables were associated with the least difference in such countries, varying threefold at most.

While South Asia registered higher scores for whole grains, the intake of meat and SSBs were lower. In Latin American and Caribbean nations, legumes and nuts were ingested at higher rates, whereas sodium intake was low.

Children and adults had similar AHEI scores. However, in Central and Eastern Europe, Central Asia, Northern Africa, and the Middle East, as well as all high-income countries (HICs), adults had a much better diet than children. More specifically, U- or J-shaped curves indicated that the best diets were reported in children aged five years or younger and individuals aged 75 years or older.

Children were found to consume less fruit, vegetables, omega-3 seafood, and SSBs than adults; however, adults had a higher PUFA and sodium intake. Interestingly, higher parental education was linked to worse diet quality in South Asia, North Africa, and the Middle East, unlike the rest of the world. Children in urban areas had a higher diet quality in most of the world, except for those residing in the Middle East and North Africa.

Women, especially those in HICs, Central Asia, as well as Central and Eastern European nations, had a better diet, with the difference being as much as four as compared to men. The best scores were for fruit, vegetables, and whole grains.

Education favored a better diet quality, with more fruit and whole grains but less SSB, meat, legume, and nut consumption in urban areas. Overall, better education was linked to increased fruit, sodium, vegetables, and whole grain consumption.

Urbanites usually had a better diet, except in North Africa and the Middle East. This is likely because of variations in the choice of healthy as compared to unhealthy foods by urban dwellers versus rural communities.

Over the 18 years in which the study was conducted, the mean score increased by 1.5 due to an improvement in five regions, except for South Asia and Sub-Saharan Africa, which reported reduced scores. Vegetables, legumes, and nuts were responsible for this increase, with meat and sodium associated with lower scores.

Iran, the U.S., Vietnam, and China registered the greatest increase in AHEI scores among populous countries. Conversely, Tanzania, Nigeria, Japan, and the Philippines were among the countries in this category with reduced scores.

Upon comparing DASH and MED scores, the researchers found the same trends, with the highest scores in South Asia and lower scores in Latin America and the Caribbean. Adults had better scores, especially those with better education. Urban residence was linked to better scores only with DASH.

These scores also showed only a small improvement over the 18 years of data collection.  

What are the implications?

The study reports that diet quality continues to show significant differences and discrepancies throughout the world.

South Asia and sub-Saharan Africa led the world with the highest scores, despite being home to many of the lowest-income countries. Closer examination showed that this is due to the lower consumption of sugary drinks and meat, while healthy foods like fruits, vegetables, legumes, nuts, and healthy fats are associated with unduly low consumption patterns.

Asia is slowly increasing the consumption of meat and sodium, as are Latin American and Caribbean countries. Meanwhile, wealthy European, Middle East, North African, and Central Asian countries have a higher intake of healthy foods but scored lower in their overly high consumption of meat, sodium, and sugary drinks.  

This indicates “a dual focus on increasing healthful foods and lowering of harmful factors is essential in these regions.” Such changes must be fostered by national and grassroots-level policies to enhance food security and ensure that every citizen gets access to nutritious food at an affordable rate.