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Arnold School researchers quantify links between chronic inflammation and diet



Over time, which is more likely to increase inflammation in your body — habañero peppers or macaroni and cheese? Yes, 
it’s a trick question.

Hot peppers can start a three-alarm blaze on your tongue — and mac and cheese goes down like, well, cheesy pasta — but it’s actually colorful, flavorful foods like peppers that do the most to reduce or prevent chronic inflammation in your body. And that’s important because chronic inflammation is associated with a raft of diseases, from adult-onset diabetes and heart disease to several types of cancer.

 “The most pro-inflammatory diet on Earth is the American fast food diet,” says James Hébert, a cancer epidemiologist in the Arnold School of Public Health and director of the Cancer Prevention and Control Program. “And there are some crappy diets in northern Europe and the Middle East, as well. The simple rule of thumb is foods that are colorless, calorically 
dense and nutrient sparse are going to be pro-inflammatory.”

Conversely, foods that are colorful, flavorful and aromatic — tomatoes, green leafy vegetables, fish, strawberries, blue-berries, cherries and oranges, for example — tend to be anti-inflammatory, Hébert says.

For centuries, medical traditions in China and India have noted the link between chronic inflammation and disease. And in the past three decades, Western medicine has focused on inflammation as a cause of cancer and a host of other chronic diseases, including cardiovascular diseases and diabetes.

Hébert and his team at the Arnold School have zeroed in on the diet-inflammation link by indexing the pro- or anti-inflammatory effects of foods and food components, including phytochemicals and micronutrients. Their federally registered Dietary Inflammation Index (DII®) took 10 years to develop. The painstaking review of more than 1,900 scientific journal articles identified 45 food and food components that were found to be associated with six biomarkers of inflammation in studies of humans, laboratory animals and even cells in culture.

Besides whole foods, such as onions, garlic and ginger, and herbs like rosemary and thyme, the DII considers the effects of spices, fiber, fat, protein, carbohydrates and alcohol, as well as vitamins, minerals, flavones and flavonols.

Here's the thing — we know most people are not going to change their diet to prevent some chronic disease 10 or 15 or 30 years in the future, but you can feel the effect of an anti-inflammatory diet immediately.

James Hébert

 A score is assigned to each food or food component. These are then summed to create the overall DII score. 
Across the 100-plus populations in 39 countries that Hébert and team have examined the lowest, most anti-inflammatory, score is around -6 and the highest, most pro-inflammatory, score is around +6.

Hébert’s team scored recipes in university first lady Patricia Moore-Pastides’ cookbook, “Greek Revival,” which features Mediterranean diet-inspired dishes. The verdict? Most of them averaged an impressive -4.5 on the DII scale.

The team also developed an online dietary questionnaire tool called DII-on-Demand™ that poses about 140 diet related questions to help individuals calculate, monitor and improve their dietary inflammation.

“Here’s the thing — we know that most people are not going to change their diet to prevent some chronic disease 10 or 15 or 30 years in the future,” Hébert says, “but you can feel the effect of an anti-inflammatory diet immediately.

“Eating an anti-inflammatory diet lowers your cancer risk, lowers your Type II diabetes risk and lowers the risk of developing cardiovascular disease. But that’s not why I do it — I do it because it makes me feel better now.”

Mike Wirth, a research faculty member in the Arnold School and a member of Hébert’s team, studies the connection of chronic inflammation with mood, sleep and stress.

“A healthy diet decreases pro-inflammatory cytokines, and your mood improves as a result,” Wirth says. “The more inflammation in your diet, the worse your sleep, which is often related to being in a bad mood.”

Five years ago, Hébert founded Connecting Health Innovations as a startup company to develop and promote the DII Screener, the web-based DII-on-Demand, and other DII-related products and services.

The problem we have had in academic nutrition is that we try to sell deprivation. You think about most commercial weight loss programs, they’re all about restricting portion size without changing diet in a fundamental way.

James Hébert

“Chronic diseases are not restricted to any country, and the DII is not restricted to any population,” says Nitin Shivappa, a USC faculty member and senior scientist at CHI who did most of the reading and scoring of the more than 1,900 journal articles used to create the second version of the DII. “We have shown that just by working on diet, we can reduce cancer and other cardiovascular diseases. In my own country of India, Type II diabetes is rising alarmingly, and it’s clear that is related to an increasing adoption of a Western diet there.”

Hébert’s next goal is to work with researchers in the university’s McCausland Brain Imaging Center to measure brain responses while consuming certain foods or drinks. “If we can get to the basic issue around motivation and diet, we can win the game that we’re now losing,” he says. “The problem we have had in academic nutrition is that we try to sell deprivation. You think about most commercial weight loss programs, they’re all about restricting portion size without changing diet in a fundamental way.”

“My advice? Just eat colorful, flavorful foods – as much of them as you possibly can. I wouldn’t worry about avoiding things — don’t go the deprivation route. Just focus instead on eating bright, colorful and flavorful foods, and that should be enough to put you in a healthier place.”  


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