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Adolescence is a critical period of brain development characterized by significant changes in structure, function, and connectivity. During this time, the brain undergoes extensive remodeling, particularly in areas responsible for decision-making, impulse control, and emotional regulation. Proper nutrition is essential to support these developmental processes. However, a diet high in ultra-processed food, as is often the case on a Western diet, can disrupt proper development leading to long term damage.

A recent study from researchers at the University of Southern California examined the impact of a Western diet, “broadly defined as a diet high in processed foods, saturated fat, and simple sugars” on the brains of rats. Rats were given unlimited access “to high-fat high-sugar chow” including popular ultra-processed candy, chips and soda, while a control group had access only to “standard chow.”

“…attributed to long-term deficits in hippocampus-dependent memory function.”

While the groups of rats did not display significant differences in body weight or body composition, they did display differences in brain function. Researchers found that “early life [Western diet] consumption led to long-lasting memory impairments, regardless of consumption of a healthier diet in early adulthood.” This finding is attributed to long-term deficits in hippocampus-dependent memory function. It is important to note that adolescence is a time of substantial developmental changes in the hippocampus.

“…consumption of a junk food-based diet led to alterations in the gut microbiome.”

It was also discovered that early life consumption of an ultra-processed diet led to alterations in the gut microbiome. These changes were, however, reversed with the introduction of a “healthy” diet in adulthood.

“…an ultra-processed diet can impact more than just hippocampal functioning.”

While this study was done in rats and like all rodent studies cannot be fully translated to humans, it is important to consider the implications especially in conjunction with numerous other studies that reflect similar findings. Additionally, an ultra-processed diet can impact more than just hippocampal functioning.

Ultra-processed food is often high in calories but low in essential nutrients such as vitamins, minerals, and antioxidants. Adolescents with poor dietary habits may experience deficiencies in nutrients needed for development such as omega-3 fatty acids, iron, and B vitamins, all of which are vital for brain health. These deficiencies can impair cognitive function, mood regulation, and overall mental well-being.

“Ultra-processed foods can also trigger inflammation in the body, including the brain…”

Ultra-processed foods can also trigger low grade inflammation in the body, including the brain, especially when consumed in excess. Chronic low grade inflammation has been linked to various neurological disorders, including depression, anxiety, and cognitive decline. In adolescents, prolonged exposure to inflammatory diets may compromise the brain’s ability to develop properly, leading to long-term cognitive impairments.

“These changes may persist into adulthood, increasing the risk of cognitive decline and neurodegenerative diseases later in life.”

Other studies have also shown that a diet high in these ultra-processed “junk foods” can alter the structure and function of the brain. MRI scans have revealed differences in the volume and activity of brain regions involved in memory, learning, and self-control among adolescents with unhealthy dietary patterns. These changes may persist into adulthood and together with other risk factors may increase the risk of cognitive decline and neurodegenerative diseases later in life.

Due to the many health consequences of an ultra-processed diet in adolescence, there are lasting implications for long-term brain health and overall well-being. Chronic conditions such as obesity, diabetes, and cardiovascular disease, often associated with poor dietary choices, further exacerbate the risk of cognitive decline and dementia in later years.

“…the current food system in the United States […] is made up of over 70% ultra-processed foods.”

It is important to prioritize education as well as address the current food system in the United States, which is made up of over 70% ultra-processed foods. A focus on whole foods coupled with other interventions aim at preventing systemic low grade inflammation, such as daily exercise, stress management and adequate sleep are essential for healthy development and whole body health in adolescence.