Impact of dietary inflammatory potential and (poly)phenols on cardiometabolic health

Abstract

[eng] Obesity and cardiometabolic diseases (CMD) represent a growing health problem worldwide. The prevalence of CMD and metabolic syndrome (MetS) is increasing in adults and children. The early development of these conditions increases the risk of type 2 diabetes mellitus (T2DM) and cardiovascular disease (CVD) in adulthood, which are the leading causes of death in the world. Chronic low-grade inflammation, related to excess adipose tissue, can be affected by the inflammatory potential of diet, increasing the risk of CMD. Consumption of pro-inflammatory diets is associated with increased adiposity, alterations in the lipid profile, and an increased risk of MetS. In this context, dietary (poly)phenols have emerged as potent anti-inflammatory agents that could counteract the negative effects of a pro-inflammatory diet and improve markers of cardiometabolic health. In accordance with the above, this thesis has three specific objectives. The first is to evaluate the relationship between the inflammatory potential of the diet and cardiometabolic parameters in adolescents. The second objective is to investigate and validate the use of (poly)phenols as biomarkers of anti-inflammatory diets, as well as their impact on metabolic syndrome in two population groups: adolescents and the elderly. Finally, the third objective is to analyze the relationship between urinary phenolic metabolites and cardiometabolic health parameters in adolescents. To address these objectives, longitudinal studies were carried out in Spanish populations. The studies in adolescents were conducted with a follow-up of two years, and the studies in elderly with a follow-up of five years. The mean ages were 12 and 68 years at cohort entry, respectively. For the first objective, the relationship between the inflammatory potential of the diet, measured through the Children’s Dietary Inflammatory Index (C-DII), and cardiometabolic parameters in adolescents was evaluated. The results showed that a higher C-DII score was associated with increases in body weight, body mass index (BMI), waist circumference (WC), body fat percentage, fat mass index (FMI), and waist-to- height ratio, as well as elevated levels of total cholesterol and LDL-cholesterol, and a decrease in HDL-cholesterol levels. Based on these results, the second objective was to investigate the potential of urinary (poly)phenols as biomarkers for anti-inflammatory diets in adolescents and the elderly. The inflammatory potential of the diet was measured with the Dietary Inflammatory Index (DII) in adults and with the C-DII in adolescents. The studies demonstrated that higher (poly)phenol levels were associated with a reduction in both DII and C-DII, with significant sex differences observed in both populations. In addition, increased (poly)phenol levels were associated with reversal of metabolic syndrome in both groups. Some phenolic metabolites have been shown to have greater bioavailability and biological activity than the (poly)phenols from which they are derived. Therefore, the third objective of this thesis was to investigate the role of phenolic metabolites in the improvement of cardiometabolic parameters in adolescents. An increase in urinary enterolactone concentrations was associated with a reduction in diastolic blood pressure, as well as a decrease in body fat percentage and FMI. Protocatechuic acid (PCA) showed similar associations, with a decrease in body fat percentage and FMI. In addition, higher levels of PCA were linked to the reversal of the MetS. Finally, it was observed that an increase in vanillic acid sulfate was related to a reduction in LDL-cholesterol levels and a reversal of central obesity. In summary, these longitudinal studies highlight the relevance of diet and (poly)phenols in improving cardiometabolic health. The findings underscore the potential of (poly)phenols as a key strategy for promoting cardiometabolic health in adolescent and adult populations, particularly through adherence to anti-inflammatory diets.