Grouping Foods Based on Level Of Processing

How is the food getting grouped?

The study from the Fralin Biomedical Research Institute at VTC published in the journal Appetite contains a variety of carefully curated images of healthier choices of minimally processed foods as well as not-so-healthy choices of ultra-processed foods. The selections are matched on 26 characteristics such as macronutrients, sodium, added sugars, dietary fiber, calories, prices, and other characteristics like color and portion size. 

This work is based on the NOVA classification system which groups foods into 4 categories based on their level of processing. However, the scale is not without its downsides, as the researchers explain:

"A major criticism of the NOVA scale is that it's difficult to use or that foods are classified differently by different people," said Alexandra DiFeliceantonio, corresponding author and assistant professor at the Fralin Biomedical Research Institute. "We found that people with education in nutrition generally agreed on the food classifications, providing some data that it might not be a valid criticism."

What they did

Foods were assigned to 4 groups: 

• Unprocessed or minimally processed like fruits, vegetables, legumes, and plain yogurt
• Processed culinary ingredients like certain spices, salt, cooking oils, and butter
• Processed foods like cheese, canned vegetables, and freshly baked bread
• Ultra-processed foods like soft drinks, processed meats, most packaged breads, and food made through industrial processing with additives that are rarely found in a home pantry. 

After developing the food groups, pictures were selected to best represent either minimally processed or ultra-processed foods. The food items were prepared in a lab, then captured by a professional photographer, and controlled for consistency. Then information such as pricing, weights, and nutritional information were collected for each image. 

Once the development stage was complete, study participants were asked to rate the images across a range of qualities to generate a final set of 28 images that were matched across 26 characteristics. After this 67 nutritional professionals were recruited to objectively measure the classifications, during which they were also asked to classify the foods themselves. 

"With this food picture set we can start to infer that any differences between food pictures is due to the degree of food processing, and not all these other factors that we know are potentially impactful," said Zach Hutelin, the study's lead author and a Fralin Biomedical Research Institute-based graduate student in the translational biology, medicine and health Ph.D. program.

Why is this so important?

Ultra-processed foods are linked with obesity, heart disease, Type 2 diabetes, and certain cancers. These types of foods make up more than half of the calories that are consumed in Canada, the United Kingdom, and the United States of America. To add to this, these types of foods have been identified as a global threat to public health. 

"There is very little experimental research on ultra-processed foods, and part of what's been holding us back is better tools for measuring and assessing their effects," said DiFeliceantonio, who is also associate director of the Fralin Biomedical Research Institute's Center for Health Behaviors Research. "The more tools we can provide, the more we can learn."

The pictures and associated data are accessible via the Virginia Tech Data Repository of the Virginia Tech University Libraries to allow scientists to test various hypotheses in behavioral economic and neuroimaging studies. Currently, the photos are being used with functional MRI testing to reveal any associated brain activity.