New study calculates damage of food + lifestyle fails. What’s your score?
Hot sauce may burn the tongue, but the inner fire of inflammation brings real damage.
“We know inflammation is detrimental for heart disease, cancer and other chronic conditions,” said Suzanne Judd, Ph.D., a professor in the Department of Biostatistics. Research has demonstrated that diet and lifestyle choices contribute to inflammation. But which foods and choices do we mean, exactly?
That is the sort of question that Judd, a nutritional epidemiologist, loves to tackle. In a new study, she and colleagues at Emory University provide answers in intriguing detail.
Using data from the massive, nationwide REGARDS study led by UAB, they compiled detailed records of food choices and lifestyle characteristics from a subset of 639 participants. Then they compared these records with the same participants’ inflammatory status — as measured by blood levels of high-sensitivity C-reactive protein and interleukins 6, 8 and 10 — and calculated the strengths of association between the inflammatory markers and individual food choices and lifestyle activities. That allowed the investigators to determine specific weights for each of 19 foods and four lifestyle elements. Foods or activities with negative numbers lowered inflammation; those with positive numbers increased inflammation. (See “Fire and ice.”)
By adding up all the weights for a person’s diet and lifestyle, the researchers created two new scores: a dietary inflammation score (DIS) and a lifestyle inflammation score (LIS). The scores were validated in more than 14,200 additional REGARDS participants. “Higher dietary and lifestyle inflammation scores of all types were generally strongly, positively associated with inflammation biomarkers,” the investigators wrote in the December 2019 print issue of the Journal of Nutrition.
Fire and ice
In their paper, the researchers provided rationales for the pro-inflammatory and anti-inflammatory effects of various foods and lifestyle factors. Here are a few:
Rationale: These juicy fruit-vegetables contain beta carotene and vitamin C as well as lycopene, which is a particularly powerful antioxidant.
Rationale: Chicken is packed with L-arginine, which relaxes blood vessels and lowers platelet aggregation and monocyte adhesion, an early stage in the formation of atherosclerotic plaques.
Processed meats: +0.68
Rationale: Bacon, sausages and other processed meats contain heme iron, which increases oxidative stress in the body. They also contain omega–6 fatty acids, another inducer of oxidative stress that stimulates expression of pro-inflammatory signals such as TNF-alpha, IL–6 and IL–8 as well. Additives such as nitrites, used as preservatives in these meats, also are suspected to have pro-inflammatory properties.
Coffee and tea: –0.25
Rationale: Coffee contains antioxidants, as does tea, which also contains flavonoids. Both have caffeine, which inhibits secretion of the pro-inflammatory IL–1-beta.
Moderate drinking (1 drink/day for women, 1–2 drinks/day for men): –0.66
Rationale: Ethyl alcohol, also known as ethanol, is metabolized into acetate, which lowers levels of pro-inflammatory free fatty acids. Moderate alcohol use also increases levels of the anti-inflammatory hormone adiponectin and inhibits pro-inflammatory IL–6 molecules.
Heavy drinking (more than 1 drink/day for women or 2 drinks/day for men): +0.30
Rationale: The bad news is that ethanol is removed from the body by conversion to acetaldehyde, which causes oxidative stress.
Heavy physical activity: –0.41
Rationale: Exercise improves response to oxidative stress, increases the concentrations of anti-inflammatory cytokines and lowers inflammation in the walls of blood vessels.
Current smoker: +0.50
Rationale: Tissue injury from the toxins released by burning tobacco causes increased levels of pro-inflammatory signaling molecules.
Obese BMI: +1.57
Rationale: Fat tissue creates and releases pro-inflammatory molecules called adipokines, including TNF-alpha.
“Rather than looking at nutrients, we wanted to look more upstream at diet and lifestyle outcomes, to better understand how they are mingled,” Judd said.Two existing scoring systems, the DII and EDIP, focus on specific nutrients, rather than whole foods, Judd explained. And there is no current scoring system to gauge the effect of lifestyle on inflammation. “We wanted to create new scores that are a proxy for inflammatory status,” Judd said. “Rather than looking at nutrients, we wanted to look more upstream at diet and lifestyle outcomes, to better understand how they are mingled.” The results support the contention that “diet and lifestyle both contribute substantially [to systemic inflammation] — lifestyle more than diet — but especially in interaction with one another,” the authors wrote.
“We’ve done a lot of work to explore participants’ diet in REGARDS, because it provides a unique opportunity to examine diet from the population perspective,” said Judd, who is a co-principal investigator for that study. REGARDS, which began in 2003, was designed to learn why more African Americans die from strokes than other races, and why people in the Southeast have a higher stroke risk than people in the rest of the country. It has enrolled more than 30,000 black and white people ages 45 and older, living in 1,866 counties across the United States.
“Usually you get homogenous diet patterns in studies,” because participants come from the same region or ethnic background, Judd said. But because REGARDS has enrolled participants from across the country, and is racially heterogenous (nearly half of participants are African American), it is able to overcome these obstacles.
The next step for the DIS and LIS? Using them as epidemiological tools for future studies examining the “collective contributions of dietary and lifestyle exposures to systemic inflammation,” Judd and her co-authors write.
In addition to Judd, authors of Development and Validation of Novel Dietary and Lifestyle Inflammation Scores were Doratha Byrd, Ph.D., W. Dana Flanders, M.D., DSc, Terryl Hartman, Ph.D., Veronika Fedirko, Ph.D., and Roberd Bostick, M.D. of Emory University.Published inDiscoveries & Innovations