Inflammation is largely a good thing. It kicks in when the body is injured or subjected to an attacker like bacteria or a virus. But sometimes the immune response doesn't fade when its job is done, and this leads to low grade chronic inflammation that can harm healthy tissues over time.

What you eat can promote or reduce your body's ability to handle inflammation. Certain pro-inflammatory foods — such as refined grains and sugary beverages — tend to produce responses in the body that foster inflammation. Other foods, such as fruits and vegetables, calm the body's inflammatory response.

Type 2 diabetes, heart disease and some types of cancer are among the diseases associated with high levels of chronic inflammation.

The Dietary Inflammatory Index (DII) is a tool developed to measure the pro- or anti-inflammatory effects of different diets. When researchers from The Ohio State University calculated DII scores for 34,500 adult participants in the National Health and Nutrition Examination Survey, they found that more than half — 57 percent — consumed a diet that was considered pro-inflammatory.

The finding and the effect a pro-inflammatory diet has on Americans' health did not surprise researcher Rachel Meadows. “We have so many chronic diseases we are dealing with in this country,” she told TheDoctor in an email, and diet is a major contributor to the problem.

Not only did over half of the people studied eat a diet that fostered inflammation, only about a third ate an anti-inflammatory diet.

In the current study, DII scores were calculated based on a 24-hour dietary recall filled out by participants. Scores ranged from -9 to 8, with 0 being a neutral diet. Scores less than zero represented an anti-inflammatory diet and scores greater than zero represented a pro-inflammatory diet.

Pro-inflammatory foods include red meat, processed meat, products containing white flour and added sugar, sugar-sweetened beverages and foods containing trans fats, such as margarine, refrigerated dough and nondairy coffee creamers.

To Meadows's surprise, not only did over half of the people in the study eat a diet that fostered inflammation, only about a third of the participants ate an anti-inflammatory diet. Nine percent ate a neutral diet. “Even if you're eating enough fruits or vegetables, if you're having too much alcohol or red meat, then your overall diet can still be pro-inflammatory.”

Rather than labeling inflammatory foods as “bad,” Meadows believes it is better to think about anti-inflammatory foods as tools people can employ to boost health. “There's a potential here to think about positive interventions, such as adding more garlic, ginger, turmeric and green and black tea — which are all anti-inflammatory — to your diet.”

Diets may vary in inflammatory potential according to age, gender, education level and socioeconomic status. These differences in inflammatory potential may partly explain disparities in health outcomes between various racial, ethnic and socioeconomic groups.

Diets high in inflammatory foods were most common in men, young adults, non-Hispanic Black adults and those with less education or lower income. Meadows, a research scientist for JPS Health Network, a safety net health system in Texas, said the main reasons pro-inflammatory diets were most common in these groups were related to inability to access and eat healthy foods because of high cost and scarcity, together with a lack of education about the health effects of a poor diet.

Many people also have elevated chronic inflammation due to non-dietary factors including stress and adverse childhood experiences. “There are a lot of factors that contribute to chronic inflammation, and they all interact — even sleep is a key component. Diet can be used as a tool to combat that,” she added.

The study is published in Public Health Nutrition.