Nutritional quality has not improved in 30 years

The World Health Organization states that a healthy diet can reduce the risk of non-communicable diseases and conditions such as obesity, high blood pressure, heart disease, stroke, diabetes and cancer.

A healthy diet should include at least five portions of vegetables or fruit per day, less saturated and trans fats, more unsaturated fats of plant origin, less processed meat and less salt. These guidelines are publicly available in the media and form part of the curriculum taught to most children in schools around the world. But are we actually listening?

A comprehensive study – the first to include results for both children and adults – has now analyzed more than 1’100 different surveys on food and nutrient consumption across 185 different countries between 1990 and 2018. The researchers from the Friedman School of Nutrition Science and Policy at Tufts University drew on survey data from the Global Dietary Database, a large, collaborative compilation of data on people’s dietary behaviour. They analysed the quality of nutrition at global, national and regional levels in order to understand the changes that have occurred since 1990.

The researchers used a scale known as the Alternative Healthy Eating Index, a validated measure of dietary quality that rates people's eating habits on a scale of 0 to 100. In this system, the number 0 represents a poor diet that does not meet WHO dietary recommendations and contains high amounts of sugar, salt and saturated fats, as well as a lack of fruits and vegetables. To achieve a score of 100 on this scale, a person's diet must contain the recommended balance of fruits, vegetables, legumes/nuts and whole grains, have a minimal proportion of added sugar and salt, and consume modest amounts of fat, primarily unsaturated fats of plant origin.

The findings, published in the journal Nature Food, show that the average quality of diet across individual regions ranged from 30.3 in Latin America and the Caribbean to 45.7 in South Asia. The average score across all 185 countries included in the study was 40.3, representing a negligible increase of 1.5 since 1990. Only 10 countries, representing less than 1 percent of the world's population, had a score above 50. The countries with the highest scores were Vietnam, Iran, Indonesia and India, while the countries with the lowest scores were Brazil, Mexico, the United States and Egypt.

«Consumption of legumes/nuts and non-starchy vegetables increased over time, but the overall improvement in dietary quality was offset by increased intake of unhealthy components such as red/processed meat, sugar-sweetened beverages and sodium«, said the study's lead author, Victoria Miller, a visiting researcher at McMaster University.

These findings appear to underscore the fact that we are not truly adhering to WHO guidelines. Although there has been a small improvement globally over the past 30 years, there are clearly significant challenges in adopting healthy eating behaviors in most countries. There were indications that nutritious dietary options have become more popular in the United States, Vietnam, China and Iran, but this trend was not observed in other countries such as Tanzania, Nigeria and Japan.

Worldwide, diet was influenced by demographic factors: adult women were more likely to follow recommended dietary guidelines than adult men, and older adults ate more healthily than younger adults. Additionally, young children had better diet quality than teenagers.

«On a global average, diet quality was also better in younger children, but then declined with increasing age», said Miller. «This suggests that early childhood is an important moment for intervention strategies to promote the development of healthy dietary preferences.

Healthy eating was also influenced by socioeconomic factors, including level of education and urbanity. Globally and in most regions, more highly educated adults and children with more highly educated parents generally showed a higher overall diet quality.

«We found that both too few healthy and too many unhealthy foods contribute to the global challenges in achieving recommended diet quality», said study co-author Dariush Mozaffarian. «This suggests that policy measures that incentivize and reward more healthy foods — for example in healthcare, employer wellness programs, government nutrition programs, and agricultural policy — can have a significant impact on improving diets in the United States and around the world.«