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Dietary Inflammatory Index (DII) vs. Mental Disorders (Anxiety & Depression) (2024 Study)

The intricate relationship between dietary habits and mental health has gained significant attention.

The Dietary Inflammatory Index (DII), a novel tool measuring diet’s inflammatory potential, has been used to help us better understand the connection between diet-realated inflammation and psychiatric disorders.


  • Diet & Mental Health: The DII helps in understanding how dietary choices can influence mental disorders.
  • Multilevel Modeling: This statistical approach provides more accurate results by considering the complexity of dietary data.
  • Impact of Inflammation: Higher DII scores, indicating pro-inflammatory diets, are linked to increased mental health issues like anxiety and depression.
  • Recommendations: Adjusting dietary habits towards anti-inflammatory foods could potentially improve mental health.

Source: Frontiers in Nutrition (2024)

Intersection: Diet, Inflammation, Mental Health

Dietary Inflammatory Index (DII)

The Dietary Inflammatory Index is more than just a measure; it represents a comprehensive approach to understanding how our diet influences systemic inflammation.

Developed through extensive research, the DII incorporates a wide range of dietary components.

  • Variety of Nutrients & Foods: It includes nutrients like omega-3 and omega-6 fatty acids, vitamins (like A, C, D, and E), minerals (such as selenium and zinc), and dietary components like fiber and antioxidants. Each of these plays a distinct role in modulating the body’s inflammatory processes.
  • Pro-Inflammatory vs. Anti-Inflammatory Effects: The DII evaluates the combined effect of these dietary components to categorize diets on a spectrum from pro-inflammatory to anti-inflammatory. Foods rich in trans fats, refined sugars, and certain processed meats have pro-inflammatory effects, while fruits, vegetables, whole grains, and lean proteins tend toward anti-inflammatory effects.

Diet-Induced Inflammation & Mental Health (Mechanisms)

The pathway from diet to mental health disorders involves several biological mechanisms:

  • Chronic Inflammation & Mental Health: Chronic systemic inflammation, often exacerbated by poor dietary choices, has been linked to the development of mental health disorders. This inflammation can affect brain function in various ways.
  • Immune System Activation: Pro-inflammatory diets can activate the immune system continuously. Chronic immune activation leads to the production of inflammatory cytokines, which can cross the blood-brain barrier and potentially disrupt brain chemistry and neurotransmitter functions.
  • Gut-Brain Axis: The gut microbiome plays a critical role in both digestion and mental health. Diets high in processed, sugary, and fatty foods can alter gut flora, leading to an increase in gut permeability (leaky gut), which may allow harmful substances to enter the bloodstream and potentially affect brain health.
  • Neurotransmitter Production & Function: Inflammation can disrupt the balance of neurotransmitters, such as serotonin and dopamine, which are crucial for mood regulation. A pro-inflammatory diet might reduce the production of these neurotransmitters or hinder their function, leading to mood disorders.
  • Oxidative Stress & Brain Health: Diets high in inflammatory foods can also increase oxidative stress, damaging cells and tissues, including those in the brain. This damage can exacerbate or even initiate mental health disorders.
  • Overeating & Inflammation: Overeating, particularly of high-calorie, nutrient-poor foods, can lead to obesity and metabolic disturbances, both of which are associated with increased inflammation. This, in turn, can exacerbate mental health issues.

Specific Foods & Effects

  • Sugars and Refined Carbs: These can cause rapid spikes in blood sugar and insulin levels, contributing to inflammation.
  • Trans Fats & Certain Saturated Fats: Found in many processed foods, these can increase harmful LDL cholesterol and triglycerides, exacerbating inflammation.
  • Processed Meats & High-fat Dairy Products: Often high in saturated fats and additives, these can contribute to poor gut health and systemic inflammation.

(Related: Top 12 Antidepressant Nutrients & Foods for Depression)

Dietary Inflammatory Index (DII): High vs. Low Inflammatory Foods

The Dietary Inflammatory Index (DII) categorizes foods based on their potential to affect the body’s inflammatory processes.

Here’s a closer look at examples of highly inflammatory and anti-inflammatory foods based on the general principles of the DII.

Highly Inflammatory Foods

  1. Processed Meats: Items like sausages, bacon, and deli meats are high in saturated fats and additives, which can promote inflammation.
  2. Refined Carbohydrates: White bread, pastries, and other foods made with white flour have a high glycemic index, leading to spikes in blood sugar and inflammatory responses.
  3. Trans Fats: Found in some margarines, fried foods, and many processed snacks, trans fats are strongly linked to increased inflammation.
  4. Sugary Beverages: Soft drinks and other sugary drinks can contribute to inflammation due to their high fructose content.
  5. Red Meat: Especially when processed or cooked at high temperatures, red meat can contribute to higher inflammation levels.

Anti-Inflammatory Foods

  1. Leafy Green Vegetables: Spinach, kale, and collard greens are rich in antioxidants and vitamins that can reduce inflammation.
  2. Fatty Fish: Salmon, mackerel, tuna, and sardines are high in omega-3 fatty acids, known for their anti-inflammatory properties.
  3. Whole Grains: Foods like brown rice, whole wheat, oats, and quinoa have lower glycemic indices and are rich in fiber, which helps in reducing inflammation.
  4. Nuts: Almonds, walnuts, and other nuts are good sources of healthy fats, protein, and fiber, all of which have anti-inflammatory effects.
  5. Fruits: Berries, oranges, cherries, and grapes contain flavonoids and antioxidants that combat inflammation.

Integrating DII into Diet Choices

Understanding the DII helps individuals make informed dietary choices.

By incorporating more anti-inflammatory foods and reducing the intake of those that promote inflammation, one can potentially manage or reduce the risk of chronic diseases linked to inflammation, including certain mental health conditions.

However, it’s important to remember that diet is just one aspect of a holistic approach to health and should be complemented with other lifestyle factors like regular exercise, adequate sleep, and stress management for optimal well-being.

Findings from Study of Dietary Inflammation & Mental Health Disorders (2024)

The Tehran University study’s core finding is the statistically significant link between the Dietary Inflammatory Index (DII) and prevalent mental disorders including depression, anxiety, and stress.

This correlation remained robust even after meticulous adjustments for several variables:

  • Baseline Characteristics: These included demographic details such as age, gender, and socio-economic status. The statistical models accounted for these factors, ensuring that the observed relationships were specifically attributable to the DII rather than external demographic variables.
  • Nutrient & Food Adjustments: The study uniquely adjusted for individual nutrients and foods, which is critical given that diets are complex and nutrients often interact in non-linear ways. This adjustment indicates that the DII’s association with mental health is not just a reflection of individual nutrient effects but a more holistic dietary pattern.

Effect of Dietary Inflammatory Index (DII) on Mental Health

The relationship between DII scores and mental health was quantitatively significant:

  • Incremental Increases: The study’s findings showed that for each incremental increase in the DII score, there was a corresponding rise in the severity of mental disorders. This linear relationship is crucial as it suggests that even small changes towards a more pro-inflammatory diet can have noticeable impacts on mental health.
  • Magnitude of Impact: The magnitude of impact varied across different mental health conditions. The increase in the DII score resulted in the most significant rise in anxiety scores (4.26), followed by stress (3.55), and then depression (3.02). This variance indicates that dietary inflammation might differentially affect various aspects of mental health.

Sex & Medical Conditions vs. Mental Health

An intriguing aspect of the study was how sex and existing health conditions influenced the relationship between DII and mental disorders.

  • Sex Differences: Women exhibited higher mean scores for stress, anxiety, and depression compared to men. This sex disparity might reflect biological differences, gender-specific stressors, or even societal roles and expectations that impact dietary habits and mental health differently.
  • Influence of Underlying Diseases: Individuals with certain chronic conditions such as liver problems, hypothyroidism, CVD, and diabetes had elevated mental disorder scores. This finding is particularly revealing as it suggests a possible intersection between chronic physical conditions, dietary inflammation, and mental health. It underscores the need for integrated care approaches that address both physical and mental health in the context of chronic diseases.

Tehran University Study on Dietary Inflammation & Mental Health (2024)

Beiranvand et al. investigated the association between the Dietary Inflammatory Index (DII) and mental disorders, specifically depression, anxiety, and stress.

This study aimed to provide a more nuanced understanding of how dietary patterns influence mental health, with a particular focus on the role of dietary inflammation.


  • Design: The research was a cross-sectional analytical study, utilizing data from the initial phase of the Tehran University of Medical Sciences Employees’ Cohort Study (TEC).
  • Participants: The study included 3,501 individuals. Nutritional data was collected using a dish-based semi-quantitative food frequency questionnaire (DFQ), while mental health data was gathered through the Depression, Anxiety, and Stress Scale (DASS-42).
  • Analysis: The innovative aspect of the study was the use of multilevel modeling. This approach analyzed data at three levels – individual food items, nutrients, and the overall DII. The analysis was conducted using GLIMMIX in SAS software, which allowed for a more refined understanding of the complex relationships between diet and mental health.


  • DII vs. Mental Disorders: The study found a significant statistical association between the DII and mental disorders. Higher DII scores, indicative of a more pro-inflammatory diet, were associated with increased mean scores for stress, anxiety, and depression. Specifically, for each unit increase in DII, the mean scores for these mental health parameters increased significantly, pointing to a direct correlation between diet-induced inflammation and mental health.
  • Quantitative Findings: The increases in mean scores for stress, anxiety, and depression per unit increase in DII were 3.55, 4.26, and 3.02, respectively, all with a p-value of less than 0.001, indicating a strong statistical significance.


  • Cross-Sectional Design: Being a cross-sectional study, it can only show associations, not causation. This limits the ability to determine if the pro-inflammatory diet directly causes mental health issues or if it’s merely correlated.
  • Limited Nutritional Parameters: The DII in this study was calculated based on 25 dietary parameters, whereas the complete DII encompasses 45 food parameters. This limitation might have affected the comprehensiveness of the inflammatory assessment of participants’ diets.
  • Geographical & Cultural Specificity: The study’s findings are specific to the cohort of Tehran University employees, which may not be generalizable to other populations or cultural dietary habits.
  • Self-Reported Dietary Data: The reliance on self-reported food frequency questionnaires could introduce recall bias and inaccuracies in reporting dietary intake.
  • Potential Confounding Variables: While the study adjusted for numerous potential confounders, there’s always the possibility that other unmeasured factors could influence the results.

Correlation vs. Causation: A Reason for Skepticism in the DII-Mental Health Link

While the Tehran University study presents compelling data linking dietary inflammation with mental disorders, it’s crucial to approach these findings with a degree of skepticism, particularly concerning the nature of correlation versus causation.

Several factors suggest that the relationship between diet and mental health might not be straightforwardly causal.

Mental Disorders Influencing Dietary Choices: Individuals with mental disorders might be more inclined to consume pro-inflammatory foods. This inclination could stem from various factors, including emotional eating, where individuals turn to comfort foods (often high in sugar, fat, and overall inflammatory potential) as a coping mechanism for their mental distress.

Medication-Induced Cravings: Certain medications used to treat mental disorders can alter appetite and cravings, leading to an increased consumption of inflammatory foods. For instance, some antidepressants and antipsychotics are known to trigger cravings for carbohydrates and sugary foods, which could inadvertently increase the DII.

The Cycle of Overeating & Inflammation: Overeating, regardless of food type, can itself cause inflammation. This is due to the stress on the body from processing excess calories and the metabolic changes that accompany overconsumption. Furthermore, overeating is a common symptom in various mental disorders and as a side effect of some psychiatric medications, creating a complex interplay between diet, mental health, and inflammation.

Mental Health Treatments & Dietary Habits: Treatments for mental disorders, including both medication and psychotherapy, can lead to changes in lifestyle and eating habits. These changes might not directly relate to the individual’s voluntary food choices but rather as a response to their changing mental state or side effects of medications.

Bi-directional Relationship: The relationship between diet and mental health could be bi-directional. While a pro-inflammatory diet might exacerbate mental health symptoms, it’s also plausible that the presence of mental health disorders could lead to poor dietary choices, thus creating a feedback loop where each condition potentially worsens the other.

Causation Hurdles: Establishing causation requires more than just observing a correlation. Longitudinal studies and randomized controlled trials would be necessary to definitively determine whether inflammatory diets cause mental health issues or if it’s the mental health conditions that drive individuals towards certain dietary patterns.

Potential Applications: Modifying Diet to Improve Mental Health

Dietary Adjustments for Mental Health

The role of clinicians in integrating dietary advice into mental health care is pivotal. Here are more specific ways in which dietary adjustments can be implemented:

  1. Comprehensive Nutritional Assessment: Clinicians can start by assessing patients’ current dietary patterns, focusing on identifying pro-inflammatory foods in their diets. This could involve keeping food diaries and discussing eating habits in detail.
  2. Tailored Dietary Recommendations: Based on individual assessments, clinicians can recommend specific dietary changes. For instance, replacing trans fats found in processed snacks with healthy fats like those in avocados or nuts. They can suggest swapping refined carbohydrates with whole grains to reduce inflammation.
  3. Integration with Mental Health Treatment Plans: Dietary recommendations should be integrated into broader mental health treatment plans. This approach acknowledges the interplay between physical and mental health and reinforces the importance of a balanced diet in managing mental health conditions.
  4. Monitoring & Follow-Up: Regular monitoring of dietary changes and their impact on mental health can help clinicians adjust recommendations as needed, ensuring that dietary interventions remain effective and aligned with patients’ mental health goals.

Personalized Nutrition Plans

Nutritionists and dietitians play a critical role in translating the DII into actionable, personalized nutrition plans:

  1. DII-Based Nutritional Counseling: By understanding an individual’s DII score, nutritionists can identify specific dietary sources of inflammation. This knowledge can guide personalized advice on which foods to increase or avoid.
  2. Holistic Approach to Nutrition: Personalized plans should consider the whole person, including their lifestyle, preferences, and any physical health conditions. This holistic approach ensures the dietary plan is not only anti-inflammatory but also sustainable and enjoyable.
  3. Education and Empowerment: Educating individuals about the impact of specific foods on inflammation and mental health empowers them to make informed dietary choices. Knowledge about how certain foods affect mood and stress levels can motivate adherence to healthier eating patterns.

Takeaway: Dietary Inflammation & Mental Health

The study from Tehran University of Medical Sciences significantly contributes to our understanding of the relationship between diet and mental health.

It underscores the impact of dietary inflammation, as measured by the Dietary Inflammatory Index, on mental disorders such as stress, anxiety, and depression.

The clear association between higher DII scores and increased severity of these mental health issues highlights the potential of dietary modifications as a tool for mental health improvement.

Clinically, this study opens avenues for integrating dietary management into mental health care, offering a non-pharmacological approach to managing and potentially improving mental health conditions.

It paves the way for further research and underscores the importance of considering diet as a crucial factor in mental health strategies, both in clinical settings and public health policies.


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