In a recent study published in BMC Medicine, researchers conducted a large cohort prospective study to investigate the associations between dietary patterns and depression or anxiety symptoms.

Their results elucidate that increased consumption of confectionery, butter, added sugars, butter, and milk-based desserts was associated with increased mental health symptoms. These symptoms were aggravated by reduced fresh fruit and vegetable intake.

Study: The associations of dietary patterns with depressive and anxiety symptoms: a prospective study. Image Credit: Julia Sudnitskaya/Shutterstock.com

Food and mental health

Mental health disorders are common conditions affecting more than 970 million individuals globally, with depression and anxiety representing the leading causes of disability and disease burden.

A growing body of literature on the association between diet and mental health exists, with previous studies suggesting that high single-nutrient intake, especially saturated fats and free sugars, and low dietary fiber heighten the risk of depression or anxiety.

Sweetened beverages, meat, specific fruits and vegetables, and fish have also been identified as contributing to mental health disorder risk.

Still, these studies have the critical limitation of being single-nutrient studies, thereby failing to capture the mental health effects of diets, which generally comprise a combination of multiple nutrients consumed simultaneously. The synergistic effects of multi-nutrient diets on depression and anxiety symptoms remain hitherto uncharacterized.

About the study

In the present study, researchers employed reduced rank regression (RRR), a data-driven statistical model to characterize major dietary patterns (DPs), to holistically evaluate the association between dietary habits and mental health outcomes.

They used long-term, extensive cohort data from the UK Biobank and self-reported mental health questionnaires and clinical diagnoses.

Their dataset initially comprised 502,401 participants from the UK Biobank, a prospective cohort study of consenting adults aged between 37 and 73, conducted across the UK between 2006 and 2010. Multiple rounds of participant screening excluded those with incomplete questionnaires, abnormal energy (calorific) intakes, cancers, and insufficient covariate data

The final study population comprised 157,212 individuals, of which 70,271 were diagnosed with baseline depression and 70,070 with baseline anxiety at the start of the study.

All participants were followed up on a 3–4-month schedule for an average of 7.6 years. Depression and anxiety were analyzed separately in the study to avoid one mental health cohort confounding results from the other.

Data for dietary assessment was collected using the Oxford WebQ tool, a web-based 24-hour method of collating the consumption frequency of 206 food items and 32 beverage types. Collected data was classified into 50 groups based on nutritional similarity.

Researchers focused data analyses on energy density, fiber density, saturated fatty acids, and free sugars, given the a priori hypotheses of their role in depression and anxiety.

Mental health outcomes were measured during and at the end of the study using the Patient Health Questionnaire-9 (PHQ-9) for depression and General Anxiety Disorder-7 (GAD-7) questionnaire for anxiety.

Both are self-reporting, 3-point-scale severity questionnaires, with scores of 10 or higher confirming depression or anxiety, respectively. Covariates included age (collected at study initiation), sex, ethnicity, education level, smoking, physical activity (compiled using the International Physical Activity Questionnaire [IPAQ]), hypertension, diabetes, and cardiovascular disease (CVD) history, and Townsend deprivation index. The deprivation index is a proxy for socioeconomic status compared to others living in the same postal code.

Dietary patterns were evaluated using the RRR model. Each participant was assigned a z-score, a weighted score representing adherence to each of the DPs identified by RRR analysis. Logistic regression models were used to calculate odds ratios (ORs) with adjustments incorporated for each measured covariate. Finally, sensitivity analyses were employed to verify the results’ robustness.

Study findings

The RRR model identified four DPs, named DP1–4. Of these, DP4 was found to explain only 4.3% of the variation found in the model and was excluded from further analyses. Collectively, DP1–3 were found to explain 74.1% of the variation observed (44.0%, 20.0%, and 10.1%, respectively).

Dietary pattern 1, the “high caloric diet,” was characterized by high butter and animal-fat intake and low intakes of fresh fruits and vegetables. This dietary pattern showed strong non-linear associations with depression, anxiety and correlations with sex and physical activity

Dietary pattern 2, the “high sugar, low-fat diet,” comprised a high intake of sugary beverages, and table sugar, and low butter and animal fat. This dietary pattern did not show a linear association with mental health but a non-linear U-shaped curve, indicating that extremes of adherence (very low and especially very high) to this diet are associated with depression and anxiety.

Dietary pattern 3, the “high sugar, high fat, high fiber diet,” comprised diets containing high butter, animal fats, milk-based desserts, and low alcohol and bread consumption. This pattern is non-linearly associated with depressive and anxiety symptoms, with anxiety associations strengthened for individuals aged ≥ 60 years.

“Our findings highlight the intricate relationships between overall diet pattern and symptoms of depression and anxiety. The current analysis has yielded robust findings that increased consumption of free sugars and saturated fatty acids was associated with a heightened risk of symptoms related to depression and anxiety.”

Sensitivity analyses verified that all computations employed for DP1–3 were valid and significant.

Conclusions

The study explored the multi-food dietary association between nutrient intake and depression or anxiety. The long-term (7.6 years), large cohort (157,212) study utilized the RRR model to characterize major DPs. Three major DPs were identified, named “high caloric diet,” “high sugar, low-fat diet,” and “high sugar, high fat, high fiber diet.”

Study results highlight that diets rich in butter, animal fats, confectionery, chocolate, cheese, and sugary drink may cause gut microbial alterations, thereby contributing to an increasing risk of anxiety or depression.

Lowered consumption of fiber and fresh fruits and vegetables were found to exacerbate these conditions.

“Using the RRR approach, our findings of curvilinear relation between nutrients suggest to limit intakes of chocolate and confectionery, butter and other animal fat spreads, high-fat cheese, sugar-sweetened beverages, and other sugary drinks, table sugars and preserves, and milk-based desserts. The excessive consumption of these foods may trigger systemic inflammation, increase oxidative stress, and cause alterations in gut microbiota, thereby contributing to the risk of developing symptoms of depression and anxiety.”

Journal reference:

• Chen, H. et al. (2023) "The associations of dietary patterns with depressive and anxiety symptoms: a prospective study", BMC Medicine, 21(1). doi: 10.1186/s12916-023-03019-x. https://bmcmedicine.biomedcentral.com/articles/10.1186/s12916-023-03019-x#article-info