Although ultra-processed foods are convenient, low cost, quick to prepare or ready-to-eat, these industrial formulations of processed food substances (oils, fats, sugars, starch, protein isolates) contain little or no whole food. They result from extensive ‘physical, biological, and chemical processes’ that create food products that are deficient in original and natural food. Ultra-processed foods typically include flavorings, colorings, emulsifiers and other cosmetic additives.

While there is some evidence regarding ultra-processed food consumption and depression, data are sparse regarding other adverse mental health symptoms including anxiety and mentally unhealthy days.

Researchers from Florida Atlantic University’s Schmidt College of Medicine and collaborators explored a nationally representative sample of the United States population to determine if individuals who consume high amounts of ultra-processed foods report significantly more adverse mental health symptoms including depression, anxiety and mentally unhealthy days.

They measured mild depression, number of mental unhealthy days and number of anxious days in 10,359 adults 18 and older from the U.S. National Health and Nutrition Examination Survey.

Results of the study, published in the journal Public Health Nutrition, showed that individuals who consumed the most ultra-processed foods as compared with those who consumed the least amount had statistically significant increases in the adverse mental health symptoms of mild depression, “mentally unhealthy days” and “anxious days.” They also had significantly lower rates of reporting zero “mentally unhealthy days” and zero “anxious days.” Findings from this study are generalizable to the entire U.S. as well as other Western countries with similar ultra-processed food intakes.

“The ultra-processing of food depletes its nutritional value and also increases the number of calories, as ultra-processed foods tend to be high in added sugar, saturated fat and salt, while low in protein, fiber, vitamins, minerals and phytochemicals,” said Eric Hecht, M.D., Ph.D., corresponding author and an affiliate associate professor in FAU’s Schmidt College of Medicine. “More than 70 percent of packaged foods in the U.S. are classified as ultra-processed food and represent about 60 percent of all calories consumed by Americans. Given the magnitude of exposure to and effects of ultra-processed food consumption, our study has significant clinical and public health implications.”

Researchers used the NOVA food classification for the study, which is a widely used system recently adopted by the Food and Agricultural Organization of the United Nations. NOVA considers the nature, extent and purpose of food processing in order to categorize foods and beverages into four groups: unprocessed or minimally processed foods, processed culinary ingredients, processed foods and ultra-processed foods.

“Data from this study add important and relevant information to a growing body of evidence concerning the adverse effects of ultra-processed consumption on mental health symptoms,” said Charles H. Hennekens, M.D., Dr.PH, co-author, the first Sir Richard Doll Professor of Medicine, and senior academic advisor, FAU Schmidt College of Medicine. “Analytic epidemiologic research is needed to test the many hypotheses formulated from these descriptive data.”

According to the National Institute of Mental Health, nearly 1 in 5 adults live with a mental illness. Mental illnesses, including depression and anxiety, are leading causes of morbidity, disability and mortality.

Co-authors of this original research are Anna Rabil, Institute of Etiological Research; Euridice Martinez Steele, Ph.D., University of Sao Paolo; Gary A. Abrams, M.D., University of South Carolina School of Medicine; Deanna Ware, M.P.H., Georgetown University Medical Center and Institute of Etiological Research; and David C. Landy, M.D., Ph.D., University of Kentucky College of Medicine.

This research was funded in part by the Bertarelli Foundation.