High Dietary Inflammatory Index associates with inflammatory proteins in plasma

Background: and aim: Unhealthy dietary habits and highly caloric foods induce metabolic alterations and promote the development of inflammatory consequences of obesity and insulin resistance, which are epidemic conditions leading to diabetes and cardiovascular diseases. Describing an inflammatory effect of diet is difficult to pursue, owing to the lack of quali-quantitative dietary assessment standardization. The Dietary Inflammatory Index (DII) has been proposed as an estimator of the pro- or anti-inflammatory effect of nutritional components. Higher DII values, which indicate an increased intake of nutrients with pro-inflammatory effects, relates to an increased risk of metabolic and cardiovascular diseases in epidemiological studies. Whether higher DII values reflect biologically relevant variations of inflammatory proteins in plasma, has been poorly described today. Methods: In this cross-sectional study, seven-days dietary records from 663 subjects in primary prevention for cardiovascular diseases were analyzed to derive the intake of nutrients, foods and to calculate DII. To associate DII with the Normalized Protein eXpression (NPX), an index of abundance, of a targeted panel of 368 inflammatory biomarkers (Olink™) measured in the plasma, we divided the population by the median value of DII (1.60 (0.83–2.30)). Results: 332 subjects with estimated DII over the median value reported a higher intake of saturated fats but lower intakes of poly-unsaturated fats, including omega-3 and omega-6 fats, versus subjects with estimated dietary DII below the median value (N = 331). The NPX of 61 proteins was increased in the plasma of subjects with DII > median vs subjects with DII  median (Area Under the Curve = 0.601 (0.519–0.668), p = 0.035). Conclusion: This large-scale proteomic study supports that higher DII reflects changes in the plasmatic abundance of inflammatory proteins. Larger studies are warranted to validate.