Scientists link popular convenience foods to a measurable loss of cognitive control

New research suggests that frequent consumption of ultra-processed foods is linked to a significant decline in mental wellbeing and a higher prevalence of clinical mental distress. The findings indicate that these dietary habits may contribute to specific challenges with emotional regulation, cognitive function, and feelings of depression. This large-scale analysis was published in Frontiers in Nutrition.

Scientific evidence has already established strong connections between industrial food processing and physical ailments like heart disease and diabetes. Existing literature also points to associations between poor diet and risks of depression or anxiety.

However, the wider impact of these foods on overall mental functioning has remained less clear. The authors of the new study aimed to quantify the aggregate burden these foods place on global mental health. They sought to determine how much clinical mental distress in the general population could be specifically attributed to dietary choices rather than other life circumstances.

“We were trying to understand what is driving the diminishing mind health scores with each younger generations that we were seeing in the Global Mind Project,” said study author Tara C. Thiagarajan of Sapien Lab.

“The mind health quotient or MHQ is a metric that aggregates positive capacities and mental health symptoms into an aggregate score that reflects the ability to navigate life’s challenges and function productively. While we had looked at aspects such as smartphones and family bonds which contribute, they could not explain the whole effect. We decided to query ultra-processed food as one possibility given its growing consumption among younger generations and the increasing number of unregulated food additives, many of which are known to be neurotoxic.”

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The Global Mind Project collects mental health information through an online assessment called the Mind Health Quotient. For their study, the researchers analyzed responses from 400,787 adults across 60 countries collected in 2023.

Participants completed a comprehensive assessment involving 47 ratings covering a wide spectrum of mental symptoms and functions. These ratings generated a score ranging from distressed to thriving.

The survey asked participants how often they ate processed, packaged, or fast food not made from fresh ingredients. Examples provided included fast food, sugary drinks, microwave meals, and salty snacks. Respondents selected a frequency ranging from “rarely/never” to “several times a day.”

To analyze this complex dataset, the researchers employed advanced machine learning models capable of processing 108 different life factors simultaneously. This approach allowed them to isolate the specific influence of diet while accounting for other variables that affect mental health.

The analysis revealed a consistent decline in mental wellbeing as the frequency of ultra-processed food consumption increased. Individuals who consumed these foods several times a day scored significantly lower on mental health metrics compared to those who rarely or never ate them. The data indicates that this was a graded relationship, where each increase in consumption frequency corresponded to lower wellbeing.

Specific symptoms appeared to be more sensitive to dietary habits than others. The results showed that symptoms associated with depression, such as feelings of sadness and distress, were strongly linked to high consumption of processed foods.

Additionally, the data indicated that frequent consumers struggled more with cognitive control, such as maintaining focus. Problems with emotional control, such as managing anger, were also more prevalent in this group.

The findings suggest that if you are “feeling depressed or having challenges with emotional and cognitive control (e.g. being quick to anger or cry or having difficulty focusing), ultra-processed food consumption may be the reason,” Thiagarajan told PsyPost.

A key aspect of the analysis involved isolating diet from other potential causes of distress. The negative association between processed food and mental wellbeing remained strong even after accounting for exercise frequency and history of trauma.

Individuals who exercised regularly but consumed processed foods frequently reported lower mental wellbeing than those who exercised regularly and ate whole foods. This suggests that exercise may not fully offset the negative mental impacts of a poor diet.

The researchers also examined the role of socioeconomic status. The analysis showed that high income did not appear to act as a buffer against the effects of a processed diet.

High earners who ate processed foods frequently had mental health scores similar to low earners who rarely ate such foods. This finding suggests that the nutritional quality of food may be a more significant driver of mental wellbeing than financial resources in this context.

The researchers used their models to estimate the proportion of mental distress potentially caused by these dietary habits. The simulations suggested that between 3.4 percent and 7.8 percent of the total global sample experienced clinical-level mental distress linked to ultra-processed food. This percentage represents a significant number of individuals when applied to large populations.

In the United States and other English-speaking nations, the estimated burden was notably higher. The study estimates that among young adults aged 18 to 34 in these regions, diet could account for a substantial portion of clinical mental distress cases. The burden appeared to be lower in older populations, possibly due to different lifelong dietary habits.

“The effects are substantial. First, those who consume ultra-processed food everyday (dominated by young men) are almost 4 times more likely to have clinical mental health diagnoses than those who rarely eat ultra-processed food,” Thiagarajan explained.

“Among those who consume ultra-processed food almost everyday, our study shows that a third of clinical mental health problems among daily consumers of ultra-processed food may be because of this diet habit after controlling for numerous other possible causal factors. Second, the more you consume, the more sad and out of control you get. It’s just a sliding scale – there is no ‘good’ amount.”

The researchers discuss several biological mechanisms that might explain these findings. Ultra-processed foods often contain additives and lack essential nutrients required for brain health. These foods can disrupt the gut microbiome, which communicates directly with the brain. Disruption in this system has been previously linked to mood regulation and cognitive function.

In addition, highly processed foods are often energy-dense but nutrient-poor. Frequent consumption can displace whole foods that provide vitamins and minerals critical for neural development. The researchers suggest that the cumulative effect of these nutritional deficits may compromise the brain’s ability to function optimally.

While the sample size was extensive, the study does have some limitations. The design was cross-sectional, meaning it captured a snapshot in time rather than following people over years. This makes it impossible to prove definitively that the food causes the distress, as people with mental distress might choose different foods.

The study relied on self-reported data, which can be subject to memory errors or individual interpretation of questions. The definition of ultra-processed food can also vary between cultures and individuals. Respondents in different countries may have had different types of food in mind when answering the survey questions.

Future research is needed to validate these findings through longitudinal studies. Following participants over time would help establish whether dietary changes precede changes in mental health. The authors also suggest that clinical trials could help determine if eliminating these foods leads to direct improvements in mental symptoms.

The study implies that reducing ultra-processed food intake could be a viable strategy for improving public mental health. The results provide evidence for incorporating dietary recommendations into mental health guidelines. The researchers argue that policy interventions, such as labeling or taxation, might be necessary to shift consumption patterns.

Looking forward, the researchers “would like to understand more about the effects of different types of ultra-processed foods and also how much the effects are reversible if you stop consuming it,” Thiagarajan said.

The study, “Estimation of the nature and magnitude of mental distress in the population associated with ultra-processed food consumption,” was authored by Jerzy Bala, Oleksii Sukhoi, Jennifer Jane Newson, Priscila Pereira Machado, Mark Lawrence, and Tara C. Thiagarajan.