Understanding the Dietary Inflammatory Index and Its Uses

In the 21st century, inflammation has entered the spotlight as a key to understanding disease. A 2010 article in Science went as far as to call it “One of the most important scientific discoveries in health research in recent years.” This development has roots as early as the 1980s when pathologist Russell Ross identified an immune response in atherosclerosis. Since then, inflammation has been linked to numerous diseases, including obesity and its related health risks.

Another critical understanding is the link between food and inflammation. Certain foods increase inflammation, while others can reduce it. Adding credence to the idea that we are what we eat, science has shown that diet affects unwanted or chronic inflammation. One way in which it does this is by altering gut bacteria, which can affect the immune system. Just as certain foods are thought to cause inflammation, others are valued for their ability to lower it.

Keep in mind that inflammation is an immune response and, therefore, not always bad. In this case, we are discussing inflammation insofar as it contributes to disease states like obesity, heart disease, and diabetes. Environmental toxins and stress also contribute to inflammatory processes. However, diet may be the factor that we can best control. Below, we will share a dietary inflammatory index food list to help guide eating choices.

The Link Between Inflammation and Obesity

We already know that obesity is interconnected with many different disease states. Inflammation might be called the tie that binds them all together.

Obesity predisposes a person to pro-inflammatory states and oxidative stress. According to a 2016 study, this is because “The excess of macronutrients in the adipose tissues stimulates them to release inflammatory mediators such as tumor necrosis factor α and interleukin 6, and reduces production of adiponectin…”

A study published by the American Heart Association looked specifically at the link inflammation has with insulin resistance and, by extension, type 2 diabetes. The authors point out that obesity is associated with the expansion of adipose tissue in perimuscular fat (PMAT), among other types of fat. PMAT, in particular, is associated with insulin resistance.

Inflammation is also a risk factor for coagulation, atherosclerosis, metabolic syndrome, and other cardiovascular diseases.

What is the Dietary Inflammatory Index?

The dietary inflammatory index (DII) is a system for scoring foods according to their effect on inflammation and stress in the body. It was first developed in 2004, using data from a review of 1,943 articles published from 1950 to 2007. It was updated in 2010, as the amount of literature on the subject had doubled in just three years.

By helping patients adjust how many anti-inflammatory foods versus pro-inflammatory foods they consume in a day, we could tip the scales on how much they experience inflammation and stress.

How is the Dietary Inflammatory Index Calculated?

The DII gives foods a score. The lower the score, the more pro-inflammatory; the higher the score, the more anti-inflammatory. (This is a reversal of the scoring system first introduced in 2007.) Certain foods clearly emerge at both extremes.

The algorithm considers six well-established inflammatory biomarkers: CRP, IL-1β, IL-4, IL-6, IL-10, and tumor necrosis factor (TNF)-α. As science learns more about how each of these relates to inflammation, the scoring could be further refined.

Application of the DII in Clinical Practice

The DII is just one algorithm for organizing food by inflammatory potential. Another common example in the U.S. is the Healthy Eating Index (HEI), based on the U.S. Department of Agriculture’s Dietary Guidelines for Americans.

The DII, however, is known to mainstream audiences, and patients may already be familiar with it. That said, you may encounter some degree of misinformation that tends to accompany popular health news. Let patients know that the DII is backed by evolving science. The medical community continues to learn and expand its knowledge of inflammation and the consequences of diet.

By providing specific recommendations on foods to eat and foods to enjoy, you can help patients take action that fits their individual preferences.

Foods to Recommend for Reducing Inflammation

As you work with your patients to advise on reducing weight through dietary changes, you can also introduce recommendations for reducing inflammation. Here is a suggested dietary inflammatory index food list.

Turmeric

One of the highest-scoring anti-inflammatory foods on the dietary inflammatory index, it has a long history in traditional holistic medicine. It is often available in powder form and can be easily added to many liquid foods/drinks such as soups, sauces, coffee, tea, and smoothies. Turmeric supplements are widely available, but not as well absorbed by the body as food sources. According to Johns Hopkins Medicine, the amount found in supplements can interfere with certain medications and is especially risky in combination with certain chemotherapy drugs.

Fiber

The nutrient source of healthy gut bacteria. Feeding healthy gut bacteria helps to lower inflammation and may contribute to weight loss. The daily recommended fiber intake for women and men is around 25g and 38g, respectively, but some studies have found that even five additional grams of fiber daily can be helpful. High-fiber sources include chia seeds, lentils, chickpeas, Brussels sprouts, oranges, and soybeans. Also, eating the skin of fruits and vegetables can add more fiber to one’s diet.

Polyphenols

This group of compounds gives many plant foods their health benefits. Foods plentiful in polyphenols include coffee, cacao/chocolate, legumes, and red wine/grapes. Certain polyphenols (such as flavanols, flavones, and flavanones, found mainly in tea, herbs, olive oil, tomatoes, potatoes, spices, citrus fruits, nuts, beans, and apples) have also been associated with weight loss. Another common polyphenol found in berries (called ellagic acid) can even help reduce skin wrinkles from radiation and control blood pressure and cholesterol.

Beta carotene

Common foods that contain beta-carotene include spinach, kale, cantaloupe, oranges, and blackcurrant juice. Easy ways to consume these foods are to blend them into juices or add them to salads.

Magnesium

This mineral is generally found in seeds, such as pumpkin or chia, which can be mixed into cereal or salads. Other sources include nuts, beans, and whole grains.

Ginger, garlic, onions

These flavorful plants have long been recognized for their various health benefits and rate well in the dietary inflammatory index. Of the three, ginger is rated highest in benefit, and makes a flavorful tea.

Vitamins D, C, E, A, and B6

In the context of reducing inflammation, vitamin D (found in fish, eggs, fortified milk, and mushrooms) comes out on top. Other contenders include:

• Vitamin C (found in peppers, citrus fruits, kiwis, broccoli)

• Vitamin E (found in nuts/vegetable oils, seeds and grains)

• Vitamin A (found in leafy greens, orange and yellow fruits/vegetables, tomato products, fish oils)

• Vitamin B6 (found in chickpeas, fish, poultry, starchy vegetables).

Omega 3 Fatty Acids

Fatty fishes and other seafood (such as salmon, sardines, mackerel, tuna, and oysters) are excellent sources of essential DHA/EPA omega 3s. Meanwhile, plant sources, including seeds and nuts, supply the ALA type of omega 3s, which is also necessary and can be converted to limited amounts of EPA and DHA in our bodies.

Zinc

This common mineral, often taken for colds/flu, is found in shellfish (e.g., oysters, crabs, and lobsters) and pumpkin/squash seeds and nuts.

Foods to Recommend Avoiding

One major category of food that people seeking a healthier diet should avoid is processed foods. Increased consumption of processed foods has been identified as a risk factor for many chronic diseases, including obesity.

Other inflammatory foods include:

• Red meat

• Commercial baked goods such as snack cakes, pies, cookies, and brownies

• Bread or pasta made with white flour

• Deep-fried foods

• Foods and drinks high in added sugar, such as candy, granola bars, soda, and sweetened tea

• Foods containing trans fats such as margarine, microwave popcorn, refrigerated dough, and non-dairy creamers

Case Studies and Clinical Evidence

Studies suggest that obesity may have a causal relationship with inflammation and vice versa. Whether one causes the other, there seem to be benefits for both by embracing a DII diet, according to a narrative review published in Archives of Endocrinology and Metabolism in 2023. The authors conclude that “use of the DII may be useful for understanding the relationship between diet and the inflammatory process related to obesity.”

A cross-sectional study of 3,151 university students in Brazil looked at DII scores alongside anthropometric and sociodemographic data. It was published in Nutrition in 2020, concluding “The most pro-inflammatory diet was independently associated with a higher prevalence of overweight and obesity in individuals with high scholarity.”

Many other examples of research studies exist and may be worth exploring if you aim to recommend the DII to your patients.

Practical Considerations for Implementation

With any discussion of dietary changes, the AMA recommends actively listening to a patient. Take time to understand their interest and motivations. Suggest changes that fit into their lifestyle. The lists above provide a strong starting point, but each patient will differ. Helping them to understand the broad effects of diet and inflammation, rather than focusing only on obesity, can help avoid the stigma often associated with weight loss and place the emphasis on overall health.

The Promise of the DII

The dietary inflammatory index provides another tool for understanding and treating obesity, along with its many related health conditions. By understanding its potential, you can become better positioned to offer practical steps patients can take in their everyday lives. Guide them to consume more anti-inflammatory foods as a way to empower them in their journey towards better overall health.

Consider becoming a member of the OMA to continue deepening your expertise in treating obesity and keeping up with advancing research.

Note to reviewer(s): The food list section is taken from the original blog post with only minor changes