May 28, 2024 – It turns out it’s not the chips that top the list of potentially worst foods for your health. There are other, less obvious choices that are driving many of us to early graves.
Scientists have long linked ultra-processed foods — such as packaged snacks — yes, including those chips -- sodas, and microwaveable meals — with various health risks, including high blood pressure, heart disease, diabetes, obesity, and certain types of cancer. They’re known to contain harmful additives, colors, and emulsifiers high in sugar, saturated fat, and salt but lacking in health-promoting vitamins and fiber.
Now a new study based on 30 years of data provides surprising insights about the associations between certain foods and early death. The most notable links were seen with meat, poultry, and seafood-based ready-to-eat products, followed by sugary drinks, dairy-based desserts, and processed breakfast food.
The issue is important because Americans now get more than 60% of their daily calories from ultra-processed foods, said senior author Mingyang Song, ScD, associate professor of epidemiology and nutrition at the Harvard T.H. Chan School of Public Health.
Previous studies around ultra-processed foods and death risks often had small sample sizes and short study periods, Song said, making their findings less definitive.
But in a study published in the journal The BMJ this month, Song and colleagues tracked the long-term health of more than 74,500 female registered nurses from 11 states in the Nurses’ Health Study, which took place from 1984 to 2018, and 39,500 male health professionals from all 50 states in the Health Professionals Follow-up Study, which took place from 1986 to 2018. The study included people without a history of cancer, heart disease, or diabetes.
The participants provided information about their health and lifestyle habits every 2 years, as well as a detailed food questionnaire every 4 years. The research team also tested the participants’ overall diet quality and divided them into groups ranging from low ultra-processed food intake (about three servings per day) to high ultra-processed food intake (about seven servings per day).
Overall, over a follow-up period that averaged 34 years, there were 48,193 deaths among all the participants, including 13,557 deaths due to cancer, 11,416 due to cardiovascular disease, 3,926 due to respiratory disease, and 6,343 due to neurogenerative diseases.
Compared with those who ate the least ultra-processed foods, those who ate the most had a 4% higher risk of total deaths and a 9% higher risk of deaths from something other than cancer or heart disease, including an 8% higher risk of neurodegenerative death. However, the researchers didn’t find any significant links to deaths due to cancer, cardiovascular disease, or respiratory disease.
The links also varied across food groups. Processed meat, poultry, and seafood had the strongest and most consistent links to early death, as well as sugar-sweetened and artificially sweetened beverages, dairy-based desserts, and ultra-processed breakfast food.
At the same time, the links were lower when overall diet quality was taken into account, which may mean that having a healthy diet overall may in part limit the risk of ultra-processed food.
“We were surprised by the rather modest association of ultra-processed food consumption with mortality risk because several prior studies have shown a strong association,” Song said.
What Does This Mean?
Song and his colleagues noted that the study is observational, so they can’t determine a cause-and-effect relationship, and the current food classification system doesn’t capture the full complexity of food processing and food categories. Plus, the participants were health professionals and predominantly white, which makes the results difficult to apply across the entire U.S. population.
In another recent study, Song and colleagues found links between high ultra-processed food and depression, particularly with artificial sweeteners and artificially sweetened beverages.
Although not all ultra-processed foods should be universally restricted, making adjustments to your diet can help.
Besides being largely devoid of healthy nutrients, ultra-processed foods often contain food additives such as emulsifiers and artificial sweeteners, some of which have been shown to lead to inflammation in the gut, which can lead to health problems, said Fang Fang Zhang, PhD, chair of the nutrition epidemiology and data science division at Tufts University’s Friedman School of Nutrition Science and Policy in Boston.
Zhang, who wasn’t involved with this study, has researched ultra-processed food consumption among U.S. children, finding that kids’ consumption of these products increased dramatically in the past 2 decades and now makes up the majority of kids’ total energy.
In another recent study, she and colleagues found ultra-processed foods are often cheaper than non-ultra-processed foods for the calories consumed. The full results of the study will be presented at the 2024 American Society of Nutrition meeting in June.
Zhang said she isn’t certain it’s the low cost that drives people to eat ultra-processed food as much as it is how convenient and accessible the products are. Many also may not understand just how bad they are for health.
What Else Should I Consider?
Song and colleagues plan to continue their studies to better understand ultra-processed foods and how they affect the body. For instance, certain ingredients in the foods may lead to health issues, which could be better regulated if those ingredients were identified.
To address that, the researchers are studying biomarkers to understand how ultra-processed foods affect blood metabolites (such as amino acids and fatty acids) and the gut microbiome. Song and colleagues talked early this month at a conference about potential metabolic pathways that link ultra-processed food to an increased risk of colorectal cancer.
“While we are gaining increasing insight into the mechanism by which ultra-processed foods impact health, we need to see important health outcomes to know if the mechanisms matter,” said Barry Popkin, PhD, a professor of nutrition at the University of North Carolina, Chapel Hill, Gillings School of Global Public Health. Popkin, who wasn’t involved with this study, has researched food processing, convenience, and the nutritional quality of foods.
“The foods not only are high in many nutrients of concern, such as added sugar, sodium, and saturated fats, but they also decompose almost to the molecular level and recompose them to appear food-like,” he said. “It is this processing that appears to create the harm along with the high ingredients.”
Popkin works on large-scale regulatory actions around processed foods, including with the FDA and agencies worldwide, on policies such as sugar-sweetened beverage and junk food taxes, obesity prevention activities, and warning labels on unhealthy food.
“We now know that using a set of classes of additives offers a way globally to create laws that industries must follow,” he said. “With this knowledge, we will see countries begin to regulate ultra-processed foods.”
