Is there an association between ultra-processed food consumption and depressive symptoms?

By Bhavana KunkalikarReviewed by Lily Ramsey, LLMApr 3 2023

In a recent study published in the Nutritional Neuroscience journal, researchers assessed the potential correlation between consuming ultra-processed foods (UPFs) and the recurrence of depressive symptoms.

Study: Association between ultra-processed foods and recurrence of depressive symptoms: the Whitehall II cohort study. Image Credit: TYLim/Shutterstock.com

Background

Observational studies have established a correlation between an individual's diet quality and the likelihood of developing depressive disorders. The role of inflammation has garnered significant interest as one of the potential underlying pathways.

The purported advantageous impact of healthy diets, like the Mediterranean diet, has been attributed to the antioxidant and anti-inflammatory characteristics of plant-based foods, such as vegetables and fruits, as well as mono and poly-unsaturated fatty acids sourced from nuts, olive oil, and oily fish.

In contrast, the Western-style diet, which is distinguished by the consumption of foods that are high in trans and saturated fatty acids as well as sugary foods, adversely impacts the pathophysiological pathways that are associated with depression.

About the study

In the present study, researchers investigated the correlation between high UPF consumption and the recurrence of depressive symptoms (DepS).

The Whitehall II study is a continuing longitudinal study that involves 10,308 individuals who were selected from 20 distinct civil service departments in London. Periodic clinical evaluations were conducted for almost five years during phases three, five, seven, nine, 11, and 12.

The scope of the current study was limited to 4,554 subjects who possessed complete information on dietary evaluation, covariates at phase seven, and indications of DepS recurrence with the occurrence of a minimum of two DepS episodes since the baseline follow-up.

Participants' dietary intakes were evaluated by administering Food Frequency Questionnaires (FFQ) during phases three, five, and seven. The respondents were queried regarding the frequency of their consumption of a standard unit or serving size of each foodstuff over the previous year. The frequency of food item consumption was evaluated using a nine-point scale. The scale ranged between 'never or less than once a month' and 'six or more times a day.' The FFQ response was used to calculate the daily food consumption of each participant.

The methodology for determining nutrient intakes involved multiplying consumption frequency for individual food items by their respective nutrient content, followed by the summation of nutrient contributions derived from all food sources.

The NOVA classification was employed to classify items in the FFQ into four distinct categories based on their level of processing. Group one comprised raw or minimally processed food items, while group four consisted of UPF undergoing industrial procedures, including adding preservatives, artificial flavors, emulsifiers, and other additives.

The DepS incidence was evaluated at phase seven, phase nine, phase 11, and phase 12 using the Center for Epidemiologic Studies Depression Scale (CES-D). This scale comprised a set of 20 items that encompassed DepS symptoms.

The study's participants were asked to assess the occurrence rate of each symptom they experienced during the previous week. This assessment was conducted with a four-point scale that ranged from 'less than once per week' to 'five to seven days per week.' Individuals who scored 16 or more on the CES-D scale or received treatment with antidepressants from 2002 to 2004 and 2015 to 2016 were classified as DepS cases.

Results

The study involved the examination of 4,554 individuals who self-identified as White. Eligible individuals are more likely to be male, younger, and have a higher socioeconomic status. They also had a lesser likelihood of having DepS than excluded participants.

Also, no significant variations were observed concerning exposure to high UPF intake. During the 13-year period of observation, 588 participants experienced a recurrence of DepS. Individuals who experienced recurrent DepS exhibited a higher likelihood of being female, unmarried or divorced, and possessing lower education and socioeconomic status levels than those who did not experience recurrent DepS.

Individuals in the highest quintile of UPF consumption exhibited a greater propensity towards lower socioeconomic status and limited educational achievements. Individuals belonging to the top quintile exhibited a higher probability of being younger than those from the lower four quintiles.

The team also noted that low physical activity, higher BMI, and higher total energy consumption were related to high UPF intakes, while no relationship was noted between UPF intake and antecedent DepS.

For the distribution of recurrent DepS, there was no linear escalation in the frequency of DepS across the quintile groups of UPF. Also, only the individuals belonging to the highest quintile of UPF consumption exhibited elevated rates of recurrent DepS compared to those categorized in the four lowest quintiles of UPF intake.

Conclusion

The study findings offered novel evidence establishing a connection between prolonged consumption of UPF and a heightened likelihood of experiencing recurrent DepS over 13 years among individuals.

The study suggests that UPF consumption is linked to DepS, regardless of the overall quality of one's diet. This finding warrants further investigation into the potential negative impact of specific UPF components on the physiological mechanisms underlying depression.