What is the Dietary Inflammatory Index (DII)?
The Dietary Inflammatory Index (DII) is a comprehensive metric used to assess the inflammatory potential of a person's diet. Developed by a team of researchers, this tool systematically scores foods and nutrients based on their known effects on specific inflammatory biomarkers, such as C-reactive protein (CRP), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α). The DII provides a continuous scale, with higher, more positive scores representing a pro-inflammatory diet and lower, more negative scores indicating an anti-inflammatory diet. The goal of the index is to provide a single, quantifiable score that helps healthcare professionals and researchers understand the complex relationship between dietary patterns and systemic inflammation. By moving away from analyzing single nutrients, the DII captures the overall dietary pattern and its cumulative effect on the body's inflammatory state. The index has proven valuable in numerous studies connecting diet-induced inflammation to a variety of chronic diseases.
How is the DII calculated?
The calculation of the DII is a multi-step process that utilizes a global database of dietary and inflammatory data. Researchers first conduct a comprehensive review of peer-reviewed articles to identify the inflammatory properties of various food parameters, which include macro- and micronutrients, spices, flavonoids, and whole foods. Each parameter is assigned a coefficient based on its influence on inflammatory biomarkers. To calculate an individual's DII score, their reported dietary intake (usually collected via a food frequency questionnaire or 24-hour recall) is compared to the global reference database.
- Data Collection: Dietary intake data for up to 45 food parameters are gathered from the individual.
- Standardization: The individual's intake of each parameter is converted into a standardized Z-score, based on the mean and standard deviation of the global database. This removes the effect of different units of measurement.
- Scoring: Each standardized score is multiplied by its respective coefficient derived from the scientific literature.
- Summation: The scores for all food parameters are summed to produce a single, composite DII score for the individual.
Variants like the Energy-adjusted DII (E-DII) also exist, which adjust the score for total energy intake, offering a more nuanced understanding of dietary components relative to total calories.
Pro-inflammatory vs. Anti-inflammatory Foods
Pro-inflammatory Foods (High DII Score)
- Refined Carbohydrates: White bread, pasta, pastries, and other products made with white flour.
- Processed and Red Meats: Bacon, hot dogs, sausages, and red meat consumption are linked to higher inflammation.
- Saturated and Trans Fats: Found in fatty meats, fried foods, and partially hydrogenated oils used in many processed snacks and baked goods.
- Sugary Drinks: Sodas, sweetened teas, and fruit juices with high sugar content.
- Excess Alcohol: Chronic or excessive alcohol consumption can promote inflammatory processes.
Anti-inflammatory Foods (Low DII Score)
- Fatty Fish: Rich in omega-3 fatty acids, such as salmon, mackerel, and sardines, which reduce inflammatory proteins.
- Leafy Greens and Colorful Vegetables: Spinach, kale, broccoli, tomatoes, and bell peppers are packed with antioxidants and polyphenols.
- Fruits: Berries, cherries, oranges, and other fruits contain antioxidants that fight cellular wear and tear.
- Whole Grains: Brown rice, oats, and whole-wheat products provide fiber that supports gut health and lowers inflammation.
- Nuts and Seeds: Almonds, walnuts, chia seeds, and flaxseeds offer fiber and healthy fats.
- Healthy Fats: Extra virgin olive oil contains oleocanthal, a compound with anti-inflammatory effects.
- Spices: Turmeric, ginger, garlic, and other spices are high in beneficial antioxidants.
Health Implications of the DII
Numerous studies have shown a strong link between DII scores and the risk of developing chronic diseases. A consistently high, pro-inflammatory DII score has been associated with:
- Cardiovascular Disease (CVD): Higher DII scores are linked to an increased risk of heart attacks, strokes, and overall CVD mortality.
- Metabolic Syndrome and Type 2 Diabetes: Pro-inflammatory diets contribute to insulin resistance, a key driver of metabolic syndrome and type 2 diabetes.
- Obesity: Studies suggest a link between high DII scores, increased weight gain, and higher prevalence of overweight and obesity.
- Cancer: Higher DII scores have been associated with an elevated risk of certain cancers, including colorectal and breast cancer.
- Mental Health: Research indicates a positive association between a pro-inflammatory diet and symptoms of depression and anxiety.
By contrast, adopting a diet with a lower DII score, like the Mediterranean or DASH diet, can reduce inflammatory markers and improve overall health outcomes. The index is a useful tool for highlighting how dietary patterns over time can shift a person's baseline risk for these conditions.
How to Improve Your DII Score
Improving your DII score involves shifting your dietary patterns toward more anti-inflammatory foods and away from pro-inflammatory ones. It's about consistency over time, not just one meal.
Strategy: Focus on plant-based foods, healthy fats, and whole grains.
- Increase Fruits and Vegetables: Aim for at least 5-6 servings of colorful, antioxidant-rich produce daily.
- Prioritize Omega-3s: Incorporate fatty fish, flaxseeds, chia seeds, and walnuts into your diet.
- Choose Whole Grains: Replace refined grains like white bread and pasta with whole-grain versions, oats, and quinoa.
- Opt for Healthy Fats: Use extra virgin olive oil for cooking and dressings and limit saturated and trans fats.
- Reduce Processed Foods and Sugar: Significantly cut back on processed meats, fast food, and sugary drinks, which are major drivers of inflammation.
- Spice it Up: Use anti-inflammatory spices like turmeric, ginger, and garlic to add flavor to your meals.
Comparison of Typical High vs. Low DII Diets
| Feature | High DII Diet | Low DII Diet |
|---|---|---|
| Carbohydrates | Refined carbohydrates like white flour, sugary snacks, and sodas. | High-fiber, whole grains such as brown rice, oats, and whole-wheat bread. |
| Fats | High in saturated fats from processed meats and trans fats from margarine and fried foods. | Abundant in healthy, unsaturated fats from olive oil, avocados, nuts, and seeds. |
| Protein | Primarily from red and processed meats. | Focuses on plant-based sources like beans and legumes, plus lean animal protein like fatty fish. |
| Fruits & Vegetables | Low consumption of fresh produce. | High consumption of a wide variety of colorful fruits and vegetables. |
| Anti-inflammatory Additives | Low intake of spices and herbs. | Regular use of spices like turmeric and ginger; incorporates green tea. |
Conclusion
The Dietary Inflammatory Index (DII) is a robust scientific tool that provides valuable insight into the inflammatory impact of an individual's eating patterns. By translating complex nutritional information into a single score, it helps illustrate the link between diet and chronic, low-grade inflammation. This persistent inflammation is a known risk factor for many chronic diseases, including cardiovascular disease, diabetes, obesity, and cancer. Instead of focusing on single, isolated nutrients, the DII emphasizes the holistic nature of dietary patterns. Adopting an anti-inflammatory diet, rich in fruits, vegetables, whole grains, and healthy fats, can help lower your DII score and, in turn, your risk for inflammation-related health problems. The shift toward more conscious, anti-inflammatory eating is a powerful strategy for disease prevention and improving overall long-term health. For further information on fighting inflammation through diet, consider exploring resources from health organizations like Johns Hopkins Medicine.
