Dietary patterns with higher inflammatory potential were significantly associated with a higher incidence of cardiovascular disease (CVD) and stroke in a new pooled analysis of three prospective cohort studies.
The analysis included 210,145 US women and men followed for up to 32 years in the Nurses’ Health Studies I and II and the Health Professionals Follow-up Study.
After adjustment for use of anti-inflammatory medications and CVD risk factors, those whose dietary pattern ranked in the highest quintile of inflammatory potential had a 38% higher risk of CVD (hazard ratio comparing highest to lowest quintiles, 1.38), a 46% higher risk of coronary heart disease (HR, 1.46), and a 28% higher risk of stroke (HR, 1.28), all P for trend < .001.
Jun Li, MD, PhD, and colleagues at Harvard T.H. Chan School of Public Health and Harvard Medical School Boston, Massachusetts, published the findings of their study in the November 10 issue of the Journal of the American College of Cardiology.
The inflammatory potential of a diet was assessed using a food-based, dietary index called the “empirical dietary inflammatory pattern” or EDIP.
In an interview, Li explained that the EDIP was developed 4 years ago by many of the same authors involved with this study, including nutrition heavyweights Walter C. Willett, MD, DrPH, and Frank B. Hu, MD, PhD, both from Harvard.
“We summarized all the foods people eat into 39 defined food groups and did a reduced-rank regression analysis that looked at these 39 food groups and three inflammatory markers — interleukin-6 (IL-6), C-reactive protein (CRP), and tumor necrosis factor alpha receptor 2. We found 18 food groups that are most predictive of these biomarkers, and the EDIP was calculated as the weighted sum of these 18 food groups.”
Individuals who had higher intakes of green leafy vegetables (kale, spinach, arugula), dark yellow vegetables (pumpkin, yellow peppers, carrots), whole grains, fruits, tea, coffee and wine had lower long-term CVD risk than those with higher intakes of red meat, processed meat, organ meat, refined carbohydrates, and sweetened beverages.
The associations were consistent across cohorts and between sexes and remained significant in multiple sensitivity analysis that adjusted for alcohol consumption, smoking pack-years, use of lipid-lowering and antihypertensive medications, sodium intake, and blood pressure.
In a secondary analysis, diets with higher inflammatory potential were also associated with significantly higher biomarker levels indicative of more systemic, vascular, and metabolic inflammation, as well as less favorable lipid profiles.
“We wanted to be able to provide guidance on dietary patterns and food combinations,” said Li. “If you tell people to eat more polyunsaturated fats instead of saturated fat or trans fat, most people don’t know what foods are higher and lower in those nutrients. Also, many foods have different nutrients — some of which are good and some of which are bad — so we wanted to help people find the foods with the higher proportion of healthy nutrients rather than point out specific nutrients to avoid.”
Researchers used prospectively gathered data from the Nurses’ Health Studies I and II starting from 1984 and from the Health Professionals Follow-up Study. After excluding participants with missing diet information or previously diagnosed heart disease, stroke or cancer, over 210,000 participants were included in the analysis. Participants completed a survey every 4 years to ascertain dietary intake.
Prevention, Not Treatment
In an editorial comment, Ramon Estruch, MD, PhD, from the Hospital Clinic in Barcelona, Spain, and colleagues suggested that it might be time for better dietary guidelines.
“A better knowledge of health protection provided by different foods and dietary patterns, mainly their anti-inflammatory properties, should provide the basis for designing even healthier dietary patterns to protect against heart disease,” the editorialists write.
They added extra-virgin olive oil, fatty fish, and tomatoes to the list of foods with “established anti-inflammatory activity.”
In comments to theheart.org | Medscape Cardiology, Estruch said the findings of this new study are confirmatory of the PREDIMED trial, which showed a reduction in risk of major CV events in individuals at high cardiovascular risk assigned to an anti-inflammatory Mediterranean diet pattern supplemented with extra-virgin olive oil or nuts as compared with those assigned to a reduced-fat diet.
“The study of Jun Li et al confirms that an anti-inflammatory diet is useful to prevent cardiovascular events and, more important, that healthy dietary patterns may be even healthier if subjects increase consumption of foods with the highest anti-inflammatory potential,” he said, adding that “mechanistic explanations add plausibility to the results of observational studies.”
Estruch was the principal investigator of PREDIMED. This trial was originally published in 2013 and then retracted and republished in 2018, with some required corrections, but the results had not materially changed.
Li is supported by grants from the National Institute of Diabetes and Digestive and Kidney Diseases and Boston Nutrition Obesity Research Center. Estruch has disclosed no financial relationships relevant to the contents of this article.