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Analysis of American Diet Finds School Meals Most Nutritious

School lunch
School lunch.

 JGI/Jamie Grill/Getty Images

Key Takeaways:

  • A new study examined the trends in the nutritional quality of foods consumed away from home, in places such as restaurants, grocery stores, entertainment venues, and schools.
  • The quality of meals from schools improved significantly in the last 16 years, and the improvement was equitable across different socioeconomic subgroups.
  • Further improvements are needed at restaurants, grocery stores, worksites, and entertainment venues where food was often deemed to be poor dietary quality, with disparities noted based on race, ethnicity, income, and education level. 

When it’s time to eat, meals can be created from foods purchased at the grocery store, or may be purchased at school, from restaurants, at worksites, or from food trucks. But which of these places provide the most nourishing options?

Typically, studies of foods included in the American diet overall focus on quality or nutritional value, but not the location where the food was obtained. In new research published in JAMA Network, researchers sought to determine patterns and trends in American diet quality based on where food came from.

The researchers focused specifically on meals eaten by children and adults at different locations, and looked closely at sociodemographic subgroups.

Examining Diet Quality

This cross-sectional study included respondents from eight National Health and Nutrition Examination Survey (NHANES) cycles, which took place between 2003 and 2018. The study included 20,905 children (age 5 to 19 years) and 39,757 adults over age 20.

To collect data on eating habits, the survey participants were asked to recall the foods they had eaten in the last 24 hours, and they reported all meals, snacks, and beverages.

Diet quality was evaluated using the American Heart Association (AHA) diet score, which has a range of 0-80. The higher scores indicate healthier diets, and the diet score includes the intake of fruits, vegetables; whole grains; fish and shellfish; nuts, seeds, legumes; sugar-sweetened beverages, processed meat; sodium, and saturated fat.

Diets were placed in one of three categories:

  • Poor diet: <40.0% adherence (score under 32)
  • Intermediate diet: 40-79.9% (score between 32-63.9)
  • Ideal diet: >80% (score over 64)

The data was analyzed from April to July 2020. The researchers paid attention to subgroups that have been susceptible to health disparities, and examined groups by age, sex, race/ethnicity, educational level, and household income.

Statistical analysis included NHANES sampling, mean proportions of calories consumed; mean AHA diet scores, and proportions of individuals meeting poor, intermediate, or ideal AHA diet quality targets.

What the Study Found

The researchers found that the best quality meals came from schools, where only 24 percent of meals were deemed to have poor nutritional quality. This was the area with the largest improvement over the last 16 years, and the improvement was equal across population subgroups. This was certainly the bright spot in this research. 

At grocery stores, 33 percent of adult meals and 45 percent of children's meals were deemed to be poor quality. This improved slightly over the last 16 years, due to a decrease in consuming sugar-sweetened beverages and an increase in eating whole grains.

At entertainment venues and food trucks, 44 percent of adult meals and 52 percent of children's meals were poor quality, which has worsened over the last 16 years.

At work sites, 51 percent of meals were poor quality, with no major change over the last 16 years. 

Restaurants fared the worst in the study, with 65 percent of adult meals and 80 percent of children's meals deemed to be poor nutrition quality. Over 16 years, this number has decreased, but only in high-income households.

“The American diet has been slowly improving in recent years, but given where we started, things are still pretty bad overall,” says Dariush Mozaffarian, Dean, Friedman School of Nutrition Science & Policy, Tufts University, and one of the study authors.

“And we see persistent or worsening disparities in nutrition by race, ethnicity, income, and education.”

Focusing on Disparities

While healthy meals in schools were equal across all races, ethnicities, income and education levels, Mozaffarian notes that worsening disparities were seen in grocery stores meals.

Dariush Mozaffarian, MD, DrPH

These disparities in nutrition security are emblematic of long-standing inequities and barriers to healthy eating in our food system.

— Dariush Mozaffarian, MD, DrPH

The nutritional quality of grocery store foods improved in high-income households, but barely moved in low-income households. What remains the biggest problem is that not everyone has equal opportunity or access when it comes to nourishing food.

“These disparities in nutrition security are emblematic of long-standing inequities and barriers to healthy eating in our food system,” says Mozaffarian.

“We face an epidemic of diet-related conditions, including obesity diabetes, cardiovascular diseases, and cancers, that are major preventable causes of suffering, death, reduced productivity, and skyrocketing healthcare costs," says Mozaffarian. "We’re only going to fix these problems by fixing the system.”

Mozaffarian explains that one overarching solution is to measure and implement true cost accounting, where we assess and value different foods and beverages based on their true overall societal costs. 

This would help get us on the path to achieve nutrition security for all, and would need to include changes with healthcare systems, government and academia (to accelerate science and innovation).

Improvements in Schools

US children seemed to fare the best in this study, with school meals coming out on top.

Montana-based dietitian Dayle Hayes, lead author of the Academy of Nutrition and Dietetics Position Papers on School Nutrition Services and the creator of School Meals That Rock, says the major changes in school meals started in 2010 after the Healthy, Hunger-Free Kids Act (HHFK) passed by Congress and was signed into law by President Obama.

The new legislation authorized funding and set policy for USDA's school breakfast, lunch and summer food programs, and allowed real reforms in school lunches for the first time in over 30 years.

Hayes says that since HHFK was enacted, it has increased the expansion of Farm to School programs and increased focus on culinary training for school nutrition professionals and school chefs. 

“A typical school lunch includes whole grains, lean proteins and a variety of fruits and vegetables,” says Hayes. “Serving sizes and sodium levels are specified by age group and there is lots of delicious flexibility for schools to offer meals that appeal to students, introducing them to new flavors while respecting cultural traditions and food preferences.”

Mozaffarian says that after 2010, school meals rapidly became the healthiest overall meal in the nation, with only 24 percent being of poor quality, down from 56 percent in 2003. 

“We found increased consumption of whole grains, fruits, and greens/beans, and decreased sugar-sweetened beverages (SSBs), refined grains, added sugar, and saturated fat at schools,” says Mozaffarian, who adds that improvements were seen equitably across subgroups.

HHFK is a great example of how a single federal policy can improve nutrition and equity.

Despite these improvements, it’s important to note that school meals provide less than 10 percent of calories in the average child’s diet, so it’s vital to improve nutrition at other checkpoints, including grocery store items (which account for 65 percent of children’s calories) and restaurants (19 percent of calories).

How have things changed since COVID-19?

Since the research on this study was collected up until 2018, it will be interesting to see how the numbers may change due to the pandemic.

A recent study that examined how school nutrition programs fared during COVID-19 had a favorable review. It found that the programs demonstrated “flexibility, resilience, and commitment to children during this crisis” and are a model example of how to pivot successfully in a crisis.  

Dayle Hayes MS, RD

School nutrition professionals have been true heroes during the pandemic, making certain that children were fed even if it meant putting themselves at risk.

— Dayle Hayes MS, RD

“The good news is that school nutrition programs have been serving meals for children (and sometimes families too), often with 24 hours of school closures last March 2020,” says Hayes.

“School nutrition professionals have been true heroes during the pandemic -- making certain that children were fed even if it meant putting themselves at risk," says Hayes. "The meals, meal kits and meal boxes that they have served -- through heat, cold, snow and rain -- have been an actual lifeline to families everywhere in the USA.”

And what about the meals from restaurants, stores and other venues? Mozaffarian says that early indications suggest different people have responded in two very different ways: 

“Some have started to cook, realized their metabolic health is crucial to lowering risk from COVID, and embraced healthy eating,” says Mozaffarian. “With all the challenges and stress, many others have turned to convenient junk foods and comfort foods, gaining weight and losing health.”

Mozaffarian says with the country turned toward the recovery from COVID, it’s a good time to more the nation towards a nourishing diet.

“USDA Secretary Vilsack has been leading this charge, talking about the importance of nutrition security for all,” says Mozaffarian. “Some Congressional leaders are recognizing the power of food to heal, improve resilience, and address long-standing disparities. We are at a unique moment in time to re-imagine our food system to be nourishing for all people and the planet.”

What This Means For You:

If you have children in K-12 schools, they are likely receiving school meals that have good nutritional quality. However, 90 percent of a child’s calories come from other places, so it's vital to see improvements at restaurants and grocery stores too. Most importantly, proper nourishment should be equitable and available to all Americans.

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  1. Liu J, Micha R, Li Y, Mozaffarian D. Trends in food sources and diet quality among us children and adults, 2003-2018. JAMA Netw Open. 2021;4(4):e215262. doi:10.1001/jamanetworkopen.2021.5262

  2. Patten EV. Disaster management and school nutrition: A qualitative study of emergency feeding during the COVID-19 pandemic. Journal of the Academy of Nutrition and Dietetics. 2021;0(0). DOI:https://doi.org/10.1016/j.jand.2021.04.012