The average American gets over half their calories from ultra-processed foods, which may be shortening their lives—but also lengthening them in a handful of cases, report Tufts University researchers.
Their analysis of the eating habits of nearly 40,000 U.S. adults, published November 26 in the Journal of the Academy of Nutrition and Dietetics, found that higher consumption of ultra-processed foods—products manufactured via multiple steps with preservatives, additives, and chemicals not used in home cooking—increased the risk of death from all causes.
Researchers at the Friedman School of Nutrition Science and Policy found that for every 10% increase in calories from ultra-processed foods, mortality risk rose by 9%. This means that someone who gets 60% of their calories from these products—which are often packed with added sugars, salt, and carbohydrates, and often lacking in nutrients such as dietary fiber, vitamins, and minerals—has a 27% greater chance of dying of all causes compared to someone who limits these foods to 30% of their diet.
The exceptions were ultra-processed whole grain breads and cereals, which were associated with neither positive nor negative impacts on health, and ultra-processed vegetables and legumes, which were associated with a reduced likelihood of death.
The study provides evidence that the harmful effects of ultra-processed food cannot be entirely attributed to its poor nutritional quality, but more research needs to be done to investigate other contributing factors such as additives, changes in food structure, etc.
“Our data suggest that ultra-processed foods are not made equal, and it’s possible for processing to make food delicious and convenient, but also keep it healthy,” said first author Lu Wang, an epidemiologist and research assistant professor at the Friedman School. “Higher consumption of fiber, even when part of ultra-processed meals such as vegetable burgers, is not associated with adverse outcomes.”
Wang’s research has been helping to measure just how much ultra-processed food we eat, and how unhealthy it is for us. In the United States, approximately 57% of the total calories consumed by adults and 67% by children come from products like sugary cereals, flavored yogurts, and frozen meals, which makes Americans among the highest consumers globally of ultra-processed foods.
Americans’ consumption of ultra-processed foods is at an all-time high, with more than half of our calories at home coming from such products—which is partly due to our changing eating habits, according to senior author Fang Fang Zhang, nutritional epidemiologist and Neely Family Professor at the Friedman School.
“Decades ago, people would sit together to eat dinner, but right now, think about how many times we eat out, or grab prepared meals or packaged snacks that we end up eating in front of the computer or television,” Zhang said. “The change in those family traditions over time is likely an important contributor to why we’re seeing a higher proportion of ultra-processed foods in our diet.”
From one angle, ultra-processed foods could be considered an American success story. They reflect advances in food technology, pushed by the U.S. Department of Agriculture in the 1980s, that made it possible to increase crop yields and package them to meet the nation’s growing calorie needs.
But over time, multiple studies have claimed that these foods—which now make up most of our supermarket aisles—are causing an obesity epidemic and increasing rates of cardiometabolic disease, and may even be addictive.
While multiple studies have looked at the impact of ultra-processed foods on mortality, the new paper from Wang, Zhang, and colleagues is one of the most comprehensive to date. They started by looking at eating habit data from a U.S.-representative population of 38,148 adults collected over two decades, between 2003-2004 and 2017-2018. The researchers then took this information—gathered from the National Health and Nutrition Examination Survey (NHANES), which asks participants to recall all food consumed within a 24-hour period during check-in calls—and checked mortality outcomes for each of these individuals through the National Death Index.
The research team will continue to explore the nuances of ultra-processed food consumption and its health effects to shape future dietary guidelines that can support Americans eating better and living longer lives, Wang and Zhang said.
“To reduce the chronic disease burden attributable to poor diet, should public health policies target all ultra-processed foods, or only specific groups of them?” said Zhang. “That’s one of the important questions that we need to do more research to answer.”
By Joseph Caputo
Citation: Complete information on authors, funders, methodology, and conflicts of interest is available in the published paper.
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