Ultra-Processed Foods on Mental Health and Function

Ultra-processed foods (UPFs) have infiltrated and dominated the U.S. food supply. From soda to cereals, companies often advertise to consume these manufactured products from the moment we wake up until we return to bed. Although convenient, affordable, and long-lasting due to its processing, UPF has additional components that can harm health even further than a typical processed dish, such as considerable amounts of added sugars, saturated and trans fatty acids, salt, and other additives. With boosts in these ingredients, ultra-processed foods can be highly addictive, steering eating selection and behavior. When ingested, neurons may release a reward neurotransmitter, dopamine, which then travels through the brain’s mesolimbic reward-processing and executive function pathways. Research reveals that alongside other factors like genetics and microbiome alterations, this process contributes to UPF addiction and shares comparable neural mechanisms to substance addiction.

It is valuable to administer self-control after getting that sugar ‘high,’ but this may become more challenging if the amount of sugar, fats, and salts we eat remains heightened for extended periods of time. This is because the brain cells responsible for regulating our behaviors, including what, the amount, and the frequency we eat, have been shown to be affected by UPF. Essentially, our own brain can encourage overeating or compulsive eating. These cells are also responsible for additional cognitive processes, such as assisting us in making decisions and storing short-term memories. A preliminary study found that when obese or overweight people who reported consuming excessive amounts of sugar were instructed to stop, withdrawal symptoms—intensified cravings, cephalgia, brain fog, and decreased ratings of happiness—appeared, further demonstrating the widespread effects UPF components have on neural activity. Animal studies show that too much salt also affects the brain by causing the gut to raise quantities of inflammatory molecules, hindering typical brain-gut communications and function. Moreover, elevated saturated fatty acids and trans fatty acids are also associated with diminished mental function, as related to inflammation within brain tissue. So, once started on UPFs, there are psychobiological explanations as to why it may be hard to put them down.

Although more research needs to be conducted to provide evidence of a causal relationship between UPF and disrupted neural functions, studies have already pointed out significant relationships between the two, particularly in people with obesity. For example, Contreras-Rodriguez et al. (2023) identified that when the percentage of UPF in an obese person’s daily diet increased, so did both the severity of reported depressive symptoms and white blood cell count. When looking at the brain, participants also showed a significantly decreased volume of regions in the reward mesocorticolimbic system with increasing UPF diets. These brain areas are critical for motivation, delayed gratification, and the development and activation of habitual behaviors. Therefore, such neural modifications correlated with consistently eating a lot of UPF are also paired with behavioral and emotional dysregulation, as indicated by the recorded symptoms of food addiction and depression. Accumulation of additives and other addictive characteristics of UPF can manifest these symptoms by reducing the variety and supply of beneficial gut bacteria, having deleterious effects on immune, hormonal, and neuronal processes.

Therefore, by being aware of the effects UPFs have on the brain, we can exert greater control over our quality of health through diet. Furthermore, by funding research projects examining the short-term and long-term consequences of UPF, we can hope for policy and industry changes that feed a brighter future.