Three National Institutes of Health grants fund study on the effects of ultra-processed foods on the human body

Scientists in the Virginia Tech College of Agriculture and Life Sciences are investigating the effects of ultra-processed foods on the human body using a variety of research tools.

Researchers will use three grants received by the Department of Human Nutrition, Foods, and Exercise to study ultra-processed foods' impact on reward processing and energy intake in adolescents, vascular health, and glucose homeostasis in mid-life adults. The study involves faculty in the college as well as others at Virginia Tech and at Duke University.

An average of 58 percent of calories consumed daily in the United States come in the form of ultra-processed foods, which are commonly referred to as foods that contain ingredients that are not used in the home kitchen, such as commercially manufactured flavorings, colorings, emulsifiers, and ingredients such as high fructose corn syrup and protein isolates.  

“An easy rule of thumb for ultra-processed at the grocery store is if the food comes in a crinkly package in the middle aisles,” said Alexandra DiFeliceantonio, an assistant professor in the department and faculty member of the Fralin Biomedical Research Institute at VTC. “Some foods are in a gray area, like some potato chips that contain only potatoes, vegetable oil, and salt. While these are industrially produced, they don’t contain ingredients that make them ultra-processed.”

With the American diet high in ultra-processed foods, not much is known about the effects on the human body, and the grants from the National Institutes of Health, which total more than $1.3 million, aim to begin the process of providing definitive answers on the impact on human health.

The first of the grants, led by co-principal investigators Brenda Davy, a professor in the department, and DiFeliceantonio, target the influence of ultra-processed foods on reward processing and energy intake in humans.

The study will be run on a “normal” American population, which is sedentary with low physical activity. Athletes are different from the rest of the population and are not a part of these studies.

“We have a basic understanding that processed foods are bad, but a lot of that research comes from what we call correlational studies where you look at what’s been eaten and then general health and health outcomes,” DiFeliceantonio said. “But that’s not particularly good evidence. What we’re doing, which is much stronger, is changing something in a person’s diet and seeing the changes in the brain and the changes in behavior.”

Participants will go into an fMRI machine and their brains will be studied as they’re tasting ultra-processed foods, both before and after dietary interventions.

The researchers will then look at the effects on executive functions and cognitive tasks, such as impulse control. Finally, food intake will be studied, such as trends with overeating with these kinds of foods.

The diets will be administered by Davy’s lab and will consist of variations in percentages of ultra-processed foods. Cognitive tests will be done in collaboration with Ben Katz in the Department of Human Development and Family Science in the College of Liberal Arts and Human Sciences.

Davy is the principle investigator of another one of the National Institutes of Health grants on ultra-processed food consumption, gut microbiota, and glucose homeostasis in mid-life adults.

Collaborators on this grant include Kevin Davy, a professor in the Department of Human Nutrition, Foods, and Exercise; Valisa Hedrick, an assistant professor in the department; Tina Savla, a professor of human development and family science in the College of Liberal Arts and Human Sciences; Katherine Phillips, a senior research scientist in biochemistry; and Lawrence David, an associate professor of molecular genetics and microbiology at Duke University.

Using her metabolic kitchen and dining laboratory, Brenda Davy is feeding people a controlled diet for several weeks so the researchers know exactly what the participants consume daily.

Participants arrive in the morning in a fasted state – nothing to eat or drink – and have breakfast in the lab and take home a cooler bag with lunch, dinner, and snacks for the rest of the day.

“We ask them to tell us if they deviate from the diet, but we also have several dietary biomarker measures in the study that provide us information on sodium, potassium, and nitrogen excretion, which should align with what we are feeding them,” Davy said. “By setting up the study this way, we overcome a major problem with using self-reported dietary intake data.”

The results of the study will aim to show direct cause-and-effect relationships between ultra-processed food intake and indicators of Type 2 diabetes risk as well as actions that could be taken to reduce reliance on ultra-processed foods if needed.

The final of the three grants is focused on the vascular consequence of ultra-processed foods in middle-aged adults, with Kevin Davy as principal investigators with Brenda Davy, Hedrick, Savla, and Phillips as co-investigators.

With ultra-processed foods being linked to cardiovascular disease and age as an additional risk factor, researchers in the department are studying if ultra-processed foods are implicated in the age-related decline in vascular health and an increased risk for cardiovascular disease.

This project is focused on people aged 50 to 65 and uses a similar design as the ultra-processed food consumption, gut microbiota, and glucose homeostasis study. The major difference is the outcomes – one is looking at glucose homeostasis and the other at vascular function.

After being on the controlled diet, researchers will look at participants' vascular function using a high-resolution ultrasound combined with measurements of blood pressure.

“The idea is that an artery that dilates more following this stimulus is a healthier artery,” Kevin Davy said. “Our controlled feeding approach is a powerful and novel method to control our studies. We're doing something that others have not done in this regard in terms of the ability to manipulate the ultra-processed food in the diet to study vascular and metabolic health.”