People who consume high amounts of ultra-processed foods report significantly more adverse mental health symptoms, according to new research published in Public Health Nutrition.
Ultra-processed foods consist mostly of manufactured ingredients that have been extracted from foods and usually contain flavorings, colorings and other additives. Ultra-processed foods are often high in sugar, fat, and salt, and they frequently lack important nutrients like fiber and vitamins. A number of studies have found that ultra-processed foods can have negative consequences for physical health, but less is known about the link between these food substances and mental health outcomes.
“I am a chronic disease epidemiologist and as such I am interested in a variety of different hypothesized disease causing exposures, and various health outcomes,” explained study author Eric Hecht, a physician and an adjunct professor at Florida Atlantic University and the University of Miami. “Ultra-processed food is of tremendous interest for a variety of health outcomes including obesity and inflammatory diseases.”
“Other studies have also explored the relationship between diet and mental health, but few have examined the relationship between UPF consumption and mental health. Anecdotally, I have often wondered about a relationship between junk food and subsequent behavioral issues in kids and symptoms of anxiety and melancholy in adults. All of these ideas sort of led to this study.”
For their study, the researchers examined 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, a series of nationally representative surveys that include both interviews and physical examinations. Importantly, the surveys collect information regarding diet behaviors and mental health.
Hecht and his colleagues found evidence that the consumption of ultra-processed foods was associated with worse mental health outcomes. Individuals who consumed the most ultra-processed foods tended to have heightened symptoms of mild depression along with more “mentally unhealthy days” and “anxious days” over the past month compared with those who consumed the least amount.
“We found a dose response relationship between UPF consumption and mental health symptoms,” Hecht told PsyPost. “Others have found a relationship between whole food consumption and improvement in mental health symptoms. The average American consumes 60% of their calories in the form of UPF. For many other health reasons, this is a bad idea. And now it appears that UPF consumption might be tied to worse mental health. I think in general the average person should look at how much packaged food they are consuming and make an effort to make the majority of their calorie consumption real, unprocessed food.”
A substantial number of individuals who reported that ultra-processed foods accounted for less than 19% of their calorie intake per day had zero mentally unhealthy days and zero anxious days. “I was impressed that individuals who consume a diet with less UPF generally describe their last 30 days as being free of mental health symptoms,” Hecht said.
The researchers controlled for potentially confounding variables, such as age, BMI, race/ethnicity, poverty status, smoking status, and physical activity level. But the study, like all research, includes some caveats.
“Our study was cross-sectional so we can not be sure as to which came first, the UPF or the symptoms,” Hecht explained. “Reverse causation, meaning mental health symptoms might increase UPF consumption is a real possibility. Arguing against this however are longitudinal studies which found a temporal relationship between junk food consumption and mental health symptoms. In addition, experimental studies have found that reducing junk food improves mental health symptoms when compared to individuals who continue their poor diet.”
“The link between UPF consumption and obesity, and the link between UPF consumption and inflammation also suggest pathways towards mental health symptoms since both extra weight gain and inflammation can lead to mental health symptoms as found in other studies,” the researcher added.
The study, “Cross-sectional examination of ultra-processed food consumption and adverse mental health symptoms“, was authored by Eric M Hecht, Anna Rabil, Euridice Martinez Steele, Gary A. Abrams, Deanna Ware, David C. Landy and Charles H. Hennekens.