The Dietary Inflammatory Index (DII), often represented with a trademark as DII®, is a literature-derived tool developed to assess the inflammatory potential of a person's diet. It provides a single numerical score that reflects how a person's food intake affects systemic inflammation, measured through specific inflammatory biomarkers. This index moves beyond the traditional focus on individual nutrients, instead taking a holistic approach by evaluating overall dietary patterns. A higher, more positive DII score indicates a diet that is more pro-inflammatory, while a more negative score is associated with an anti-inflammatory diet. The DII's development began in 2004, and a revised, more refined version was released in 2014 based on an expanded review of scientific literature.
How is the DII calculated?
The calculation of a DII score is a complex process typically performed in research settings, utilizing data from detailed dietary intake questionnaires. The index is based on 45 specific food parameters, which can include macronutrients like carbohydrates and fats, micronutrients like vitamins and minerals, as well as specific foods, herbs, and spices. The process involves several steps:
- Data Collection: An individual's daily intake of each of the 45 food parameters is obtained, often via a food frequency questionnaire (FFQ).
- Standardization: The daily intake for each parameter is converted into a standardized Z-score, which compares the individual's intake to a global average derived from a reference database.
- Weighted Scoring: Each parameter is assigned a specific inflammatory weight based on a comprehensive literature review. A parameter is scored based on whether it has been shown to increase (+1), decrease (-1), or have no effect (0) on six key inflammatory biomarkers: IL-1β, IL-4, IL-6, IL-10, TNF-α, and CRP.
- Calculation: The individual's standardized score for each food parameter is multiplied by its corresponding inflammatory weight. These values are then summed to produce the total DII score for that person.
Pro-inflammatory vs. anti-inflammatory foods
The DII categorizes a wide range of dietary factors based on their established impact on inflammatory markers. Understanding this distinction is key to influencing your personal DII score.
Pro-inflammatory components
- Processed and Fried Foods: These include fast food, fried snacks, processed meats like bacon and hot dogs, and commercial baked goods.
- Refined Carbohydrates and Added Sugars: White bread, pasta, sugary beverages (soda, sweetened teas), and candy are significant contributors.
- Certain Fats: Trans fats (margarine, shortening) and excessive amounts of saturated fats (high-fat dairy, fatty meats) are considered pro-inflammatory.
- Red and Organ Meats: Excessive consumption of these is associated with higher inflammatory potential.
Anti-inflammatory components
- Fruits and Vegetables: Berries, leafy greens (spinach, kale), tomatoes, oranges, and carrots are rich in antioxidants and polyphenols that combat inflammation.
- Omega-3 Fatty Acids: Sources like fatty fish (salmon, sardines), walnuts, chia seeds, and flaxseeds are highly anti-inflammatory.
- Healthy Fats: Olive oil, avocados, nuts, and seeds provide monounsaturated fats that have a protective effect.
- Whole Grains: Whole wheat, oats, quinoa, and brown rice provide fiber and other beneficial compounds.
- Herbs and Spices: Turmeric and ginger contain powerful compounds like curcumin that are known for their anti-inflammatory properties.
Impact of the DII on health outcomes
An extensive body of research links a higher DII score to an increased risk of chronic diseases. Conversely, a lower, more anti-inflammatory score is associated with reduced risk and better management of these conditions.
Comparison: High vs. Low DII Score
| Feature | High DII Score | Low DII Score |
|---|---|---|
| Associated Diet | High in processed foods, refined carbs, red meat, and sugar-sweetened beverages. | Rich in fruits, vegetables, whole grains, nuts, seeds, and healthy fats. |
| Inflammatory Biomarkers | Linked to elevated levels of pro-inflammatory markers such as C-reactive protein (CRP) and interleukin-6 (IL-6). | Associated with lower levels of inflammatory biomarkers, indicating reduced systemic inflammation. |
| Chronic Disease Risk | Significantly associated with an increased risk of cardiovascular disease, type 2 diabetes, metabolic syndrome, and certain cancers. | Associated with a lower risk of chronic diseases and better management of existing conditions. |
| Effect on Weight | Linked to a higher risk of overweight and obesity. | Can help with weight management and overall wellness. |
| Mental Health | Associated with a higher risk of depression and anxiety. | Potential to improve mental well-being by modulating neurotransmitters and inflammation. |
| Gut Health | Can lead to imbalances in the gut microbiota, contributing to systemic inflammation. | Promotes a healthier gut microbiome, which is linked to better immune function and anti-inflammatory responses. |
How to lower your inflammatory food index
Changing your eating habits can significantly impact your DII score. Focus on shifting your diet to be more anti-inflammatory rather than strictly restricting foods, which is often more sustainable.
- Increase intake of fruits and vegetables: Aim for a wide variety of colorful options, which are packed with anti-inflammatory compounds.
- Choose healthy fats: Incorporate sources of omega-3 fatty acids like oily fish, walnuts, and flaxseeds. Use healthy oils like olive oil for cooking.
- Select whole grains: Replace refined grains with options like oatmeal, brown rice, and quinoa to increase fiber intake.
- Add herbs and spices: Incorporate anti-inflammatory spices like turmeric and ginger into your cooking.
- Limit processed and sugary foods: Reduce consumption of processed snacks, sugar-sweetened beverages, and commercial baked goods.
- Opt for lean protein: Prioritize lean poultry and fish over red and processed meats.
Conclusion
The Dietary Inflammatory Index provides a valuable scientific framework for understanding how dietary patterns influence chronic inflammation and, by extension, overall health. By moving toward a diet rich in anti-inflammatory foods and limiting pro-inflammatory choices, individuals can take proactive steps to reduce their DII score and lower their risk of chronic diseases. As research continues to validate and refine this tool, it offers a powerful way to integrate personalized nutritional strategies into patient care and public health recommendations.
For more information on the development and validation of the DII, readers can explore the foundational research published by the creators of the index. For a deeper scientific dive, consider reading the 2014 paper that solidified the DII's methodology.
