New study links ultra-processed foods to worse health

Ultra-processed foods have long drawn criticism for containing high amounts of sugar, salt, and unhealthy fat. But research has suggested the issue may extend beyond their ingredients alone.

After taking saturated fat, added sugar, and sodium into account, Tufts researchers found that diets higher in ultra-processed foods are still associated with poorer health measures. 

The results suggest the risks may be tied not only to the nutrient profiles of these foods but also to how they are made.

What happened?

The research, published in the American Journal of Public Health, drew on 20 years of data from the National Health and Nutrition Examination Surveys (which are published every other year), spanning from 1999 to 2018. 

The study was conducted by investigators at Tufts University's Food is Medicine Institute.

Using participants' dietary reports, the researchers sorted foods by level of processing and then looked at how those eating patterns aligned with body weight, blood sugar, blood pressure, cholesterol, and mortality risk.

As the share of calories coming from ultra-processed foods rose by 10%, health measures tended to worsen. Higher intake was associated with greater body weight, poorer blood sugar control, elevated blood pressure, and less favorable cholesterol, along with higher rates of diabetes, metabolic syndrome, and cancer, and a modestly higher risk of death during the study period.

These associations remained true even after the analysis adjusted for overall diet quality as well as saturated fat, added sugar, and sodium levels.

The study's senior author, Dariush Mozaffarian, said, "The findings suggest ultra-processed-food factors beyond nutrients — such as changes to foods' cellular structure, loss of beneficial chemical compounds, additives, and chemicals from packaging — may create health risks not addressed by traditional nutrition metrics or policies."

Why does it matter?

In the United States, ultra-processed foods supply an enormous share of daily calories — more than half for adults and about 60% for children.

Nutrition labels may not tell the whole story. Two foods may appear similar in sugar, salt, or fat levels, but the more heavily industrialized option could still be associated with poorer health outcomes.

That does not mean every ultra-processed food carries the same level of risk, nor does the study prove cause and effect. Because the research was observational, it identified associations rather than direct causation.

The consistency of the findings across different groups suggests processing itself may warrant closer attention from health experts and policymakers.

The study may also help explain why diets centered on ultra-processed foods often seem to take a greater toll on health over time than standard nutrition calculations alone would suggest.

Get TCD's free newsletters for easy tips, smart advice, and a chance to earn $5,000 toward home upgrades. To see more stories like this one, change your Google preferences here.