American diets improve, but remain poor for many, Tufts study says
1 of 2 | “What Americans eat is the single biggest driver of our health,” said the study’s senior author, Dr. Dariush Mozaffarian, a cardiologist and director of the Food is Medicine Institute at Tufts University in Boston. Photo by RitaE/Pixabay
Americans are eating better now than two decades ago, but disparities are continuing or worsening among vulnerable populations, a new study indicates.
The research, which reveals that the U.S. diet has a long way to go in achieving health equity, was published Monday in Annals of Internal Medicine.
Diet quality among adults improved modestly between 1999 and 2020, according to the researchers in the Food is Medicine Institute at Friedman School of Nutrition Science and Policy at Tufts University in Boston.
However, they said, the number of Americans with poor diet quality has remained stubbornly high.
Poor diet takes a toll on health. It’s a major risk factor for obesity, type 2 diabetes, cardiovascular disease and certain cancers, with more than 1 million Americans dying every year from diet-related illnesses, the Food and Drug Administration reports.
“What Americans eat is the single biggest driver of our health,” said the study’s senior author, Dr. Dariush Mozaffarian, a cardiologist and director of the Food is Medicine Institute.
The institute’s “mission is to integrate nourishing food-based therapies into health care, with supportive community, government and private sector actions to make healthier eating easier for everyone,” Mozaffarian said.
“To achieve this, it’s critical to understand the quality of the food that Americans are eating, how this has changed over time, and how this relates to disparities in our nation.”
An estimated $1.1 trillion in health care expenditures and lost productivity are due to poor diet and food insecurity. These burdens also contribute to health inequity by income, education, ZIP code, race and ethnicity, the researchers found.
“The rich are getting richer, including in the quality of food they eat,” Mozaffarian said, noting that “until very recently, our health care system and policies around equity mostly ignored nutrition. We can’t fix the problem if we’re not paying attention to it.”
He added that “most people, including doctors and government leaders, don’t realize how powerful their food choices are for their health — what a massive difference these can make, with each meal every day.”
Socioeconomically and geographically vulnerable Americans are particularly at risk for diet-related diseases, he said. As a result, it’s important to address nutrition security and other social determinants of health, such as housing, transportation, fair wages and structural racism.
Researchers examined data from 10 cycles of the National Health and Nutrition Examination Survey between 1999 and 2020. The nationally representative sample involved repeated 24-hour dietary recalls, where people reported all foods and beverages consumed during the previous day.
A total of 51,703 adults completed at least one valid 24-hour recall, with 72.6% doing two recalls.
The American Heart Association diet score measured participants’ intake of fruits, vegetables, beans and nuts, whole grains, sugary beverages and processed meat.
Over two decades, the share of adults with poor dietary quality decreased to 36.7% from 48.8%, while those with intermediate diet quality increased to 61.1% from 50.6%. The proportion of adults with an ideal diet improved, but remained strikingly low, rising to 1.58% from 0.66%.
Specific changes contributed to these trends, including greater consumption of nuts, seeds, whole grains, poultry, cheese and eggs. Meanwhile, there was lower intake of refined grains, drinks with added sugar, fruit juice and milk.
Total consumption of fruits and vegetables, fish and shellfish, processed meat, potassium and sodium remained relatively stable.
These improvements were not universal. Gains in dietary quality were most significant among younger adults, women, Hispanic adults and people with higher levels of education, income, food security and access to private health insurance.
Progress was less pronounced among older adults, men, Black adults and people with lower education, less income, food insecurity or non-private health insurance.
For example, the proportion of adults with poor diet quality decreased to 47.3% from 51.8% among people with lower income, to 43.0% from 50% among people with middle income and to 29.9% from 45.7% among those with higher income.
“We believe it is imperative to understand the trends and disparities in diet quality in the United States and address the potential disparities by population subgroups to promote health equity and human well-being,” said the study’s first author, Junxiu Liu.
Liu is a former postdoctoral scholar at Tufts and now an assistant professor in the department of population health science and policy at the Icahn School of Medicine at Mount Sinai in New York City.
The National Institutes of Health’s National Heart, Lung and Blood Institute funded the research.
“I hope the results of this excellent study shine a bright light that we need to change our policies in the U.S.,” said Bonnie Jortberg, a registered dietitian and associate professor of family medicine at the University of Colorado School of Medicine in Aurora, Colo. She was not involved in the new study.
Policy changes would ensure “greater accessibility to healthful foods for our most disadvantaged populations,” with improvements targeting school meals and food assistance programs while providing better access to evidence-based nutrition information, Jortberg said.
“Food insecurity affects diet quality via lower consumption of healthier foods, especially those that are more expensive, don’t have a long shelf life and don’t provide enough volume to fill a hungry child,” said Heidi Silver, a registered dietitian and director of the Vanderbilt Diet, Body Composition, and Human Metabolism Core at Vanderbilt University Medical Center in Nashville.
“All this has negative health consequences,” Silver said, adding that it’s “another aspect of structural racism in our country.”
Excess sugars and sodium and ultra-processed foods are the main culprits in diet-associated health problems, said Dr. Vanita Rahman, an internist and clinic director at Barnard Medical Center in Washington, D.C.
Meanwhile, Rahman said, people are not eating enough fruits, vegetables, legumes and whole grains, which are loaded with fiber, protein and essential nutrients that can improve gut health, lower cholesterol, regulate blood sugar levels and lead to significant weight loss.
“We have these alarming obesity rates among adults and children, and this report really illustrates why that might be the case,” she said, adding that “we need to translate research findings into practical changes in people’s lives.”