What to know about processed and ultra-processed food

Take a stroll down the middle aisles of any American grocery store, and you’ll be surrounded by rows of brightly colored packaged macaroni and cheese, instant soups and chips in all forms and flavors — all with long ingredient lists. These and other familiar favorites offer consumers a convenient, tasty and often affordable meal or snack.

Studies suggest, however, that nearly two-thirds of the average American diet consists of highly processed or “ultra-processed” foods. And growing scientific scrutiny and public concern are forcing policymakers to take a closer look at what these foods are — and what they may be doing to our health.

“We’re creating ingredients so rapidly, we don’t have time to study them,” said Alyson Mitchell, a professor and food chemist in the UC Davis Department of Food Science and Technology. “The food technology has moved faster than the health studies have.”

Adding to the uncertainty, there’s no consensus about what “processed food” is, said Charlotte Biltekoff, a professor of American studies and food science and technology at UC Davis. In her book, “Real Food, Real Facts: Processed Food and the Politics of Knowledge” (University of California Press, 2024), Biltekoff explores the tension between consumer perceptions and the food industry’s framing of processed food.

“Sometimes ‘processed’ is used very generally to refer to ‘bad’ food,” Biltekoff said. 

She said when people talk about it in this way, they are usually referring to ultra-processed foods. 

“Other times it’s used technically to describe a manufacturing process.” These different frameworks create confusion about what the term really means.

To cut through the confusion, Brazilian researchers in 2009 developed the NOVA classification system that catalogs foods by the extent and purpose of industrial processing:

• Category 1: Unprocessed or minimally processed foods — such as whole foods, vegetables, fruit, meat and pasta. These foods may have been washed, dried, frozen or vacuum-packed but have no added ingredients.

• Category 2: Culinary ingredients that have been processed, including oil, butter, sugar or salt. They are typically used only in cooking and not eaten on their own.

• Category 3: Processed foods — made by combining Category 1 and 2 foods through preservation or cooking. Examples include canned tuna, fruits in syrup and salted nuts.

• Category 4: Ultra-processed foods are industrial formulations made from food components. They include additives that are rare or nonexistent in culinary use, like emulsifiers, hydrogenated oils, synthetic colors, texture improvers or flavor enhancers. Think chips, soda, instant soup, pastries and mass-produced breads.

It’s the last category — ultra-processed foods — that has raised flags.

“A lot of the technologies that we’re using are restructuring molecules and creating molecules that we’ve never been exposed to before,” Mitchell said.

She said ultra-processed foods are not so much foods as they are formulations of foods designed to make the product more appetizing so you’ll buy more of it.

“The purpose is not necessarily to improve safety or improve the shelf life of the food,” Mitchell said. “It’s to sell a food product. It’s to make money off the food.”

Are ultra-processed foods ‘bad’ for you?

While more than 20,000 studies have examined ultra-processed foods, the vast majority have been observational. These studies report an association — but no causation — between eating ultra-processed foods and obesity, cardiovascular disease, some cancers, depression and gastrointestinal disorders, said Angela Zivkovic, an associate professor in the UC Davis Department of Nutrition.

“We have no way of telling whether the disease outcome is due to the intake of that food or whether it is a reflection of an overall diet and lifestyle,” Zivkovic said.