The American diet still has a long way to go

Unhealthy diets continue to negatively impact American adults. According to the Food and Drug Administration, unhealthy diets are a leading risk factor for obesity, type 2 diabetes, cardiovascular disease and certain cancers, and more than one million Americans die each year from diet-related diseases. Unhealthy diets and food insecurity are also costly, costing an estimated $1.1 trillion in health care costs and lost productivity. These burdens also contribute to significant health disparities based on income, education, zip code, and race and ethnicity.

According to a study published today by the Food as Medicine Institute at the Friedman School of Nutrition Science and Policy at Tufts University: Annals of Internal MedicineThe researchers found that there was a slight improvement in diet quality among U.S. adults between 1999 and 2020. However, they also found that the number of Americans with poor diet quality remains high. Most notably, disparities remain and, in some cases, have worsened.

“While Americans’ diets have improved slightly over the past two decades, those improvements have not reached everyone, and many Americans’ diets are worsening,” said Dariush Mozaffarian, cardiologist, director of the Food is Medicine Institute, and lead author of the study. “Our new research shows that the nation will not achieve nutrition and health equity unless we address the barriers many Americans face to accessing and eating nutritious foods.”

In the study, researchers looked at data from 10 cycles of the National Health and Nutrition Examination Survey from 1999 to 2020, a nationwide survey in which citizens complete repeated 24-hour dietary recalls to report all foods and beverages consumed during the previous day. The study analyzed 51,703 adults who completed at least one valid 24-hour recall, with 72.6% completing two recalls.

Diet quality was measured using the American Heart Association Diet Score, a validated measure of a healthy diet that includes fruits, vegetables, legumes, nuts, whole grains, sugary beverages, and processed meats. Researchers found that over the past 20 years, the proportion of adults with poor diet quality has decreased from 48.8% to 36.7%, while the proportion of adults with fair diet quality has increased from 50.6% to 61.1%. They also found that the proportion of adults consuming an ideal diet has improved but remains very low, from 0.66% to 1.58%.

Specific changes contributing to these trends include increased intake of nuts and seeds, whole grains, poultry, cheese, and eggs. Researchers also found decreases in intake of refined grains, sugar-sweetened beverages, fruit juice, and milk. Total intake of fruits and vegetables, seafood, processed meats, potassium, and sodium remained relatively stable.

Narrowing their analysis to key subgroups, the researchers found that these improvements were not universal. Improvements in diet quality were most pronounced among younger adults, women, Hispanic adults, and those with higher education, income, food security, and access to private health insurance. Improvements were less pronounced among older adults, men, black adults, and those with lower education, income, lower food security, or no private health insurance. For example, the percentage of adults with poor diet quality decreased from 51.8% to 47.3% among low-income adults, 50.0% to 43.0% among middle-income adults, and 45.7% to 29.9% among high-income adults.

“It’s encouraging to see some improvements, especially reduced consumption of added sugars and fruit drinks, but we still have a long way to go, especially for people from marginalized communities and backgrounds,” added lead author Junxiu Liu, a postdoctoral researcher at the Friedman School at the time of the study and now an assistant professor at the Icahn School of Medicine at Mount Sinai.

“We face a national nutrition crisis as rates of obesity and type 2 diabetes continue to rise,” Mozaffarian said. “These diseases affect all Americans, but especially those who are socioeconomically and geographically vulnerable. We must address nutrition security and other social determinants of health, including housing, transportation, fair wages and structural racism, and address the human and economic costs of unhealthy diets.”

Citation: This research was supported by grant R01HL115189 from the National Heart, Lung, and Blood Institute of the National Institutes of Health. Full information on authors, methodology, funders, and conflicts of interest can be found in the published paper.

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