Effect of Mediterranean Diet Enriched in High Quality Extra Virgin Olive Oil on Oxidative Stress, Inflammation and Gut Microbiota in Obese and Normal Weight Adult Subjects

Abstract

Introduction: The Mediterranean Diet (MD) is useful in the prevention of overweight, obesity and metabolic disease. High Quality-Extra Virgin Olive Oil (HQ-EVOO), an essential component of this diet, exerts protective effects against chronic diseases. Gut Microbiota (GM), recognized as a key factor in driving metabolic activities, is involved in the regulation of host immunity. Lactic Acid Bacteria (LAB) and their probio-active cellular substances produce beneficial effects in the gastrointestinal tract. Materials and Methods: Eighteen overweight/obese subjects (cases, BMI ≥25 kg/m2) and 18 normal weight controls (BMI 18.5-24.9 kg/m2) were fed with MD enriched with 40 g/die HQ-EVOO for three months. Feces and blood samples were collected at time 0 (T0) and after three months (T1) for LAB composition, oxidative stress, metabolic and inflammation parameter determinations. Results: Myeloperoxidase and 8-hydroxy-2-deoxyguanosine, markers of inflammation and oxidative stress, were significantly decreased after MD rich in HQ-EVOO both in controls and in cases. Proinflammatory cytokines levels were significantly decreased in cases in comparison to controls, while IL-10 and adiponectin were significantly increased in cases. LAB's rpoB copies/ng of DNA increased 55.6 folds in cases compared to their baseline after MD rich in HQ-EVOO. MD rich in HQ-EVOO increased adiponectin and IL-10 concentration in overweight/obese subjects and decreased oxidative stress and inflammation parameters and at the same time, increased LAB number in GM. Discussion: Our results indicate that MD rich in HQ-EVOO induces an increase of LAB in GM and could have a potential role in the prevention of inflammation. Clinical Trial Registration: www.ClinicalTrials.gov, identifier NCT03441802.

Keywords: adiponectin; cytokines; high quality-extra virgin olive oil; lactic acid bacteria; mediterranean diet; microbiota; prevention and rehabilitation.

Copyright © 2019 Luisi, Lucarini, Biffi, Rafanelli, Pietramellara, Durante, Vidali, Provensi, Madiai, Gheri, Masini and Ceccherini.

Figures

Figure 1

Evaluation of myeloperoxidase (MPO) activity. Bar graph shows the plasma levels of the enzyme in controls and cases at T0 and T1. Delta (Δ) values are calculated by subtracting the final value at 3 months from the corresponding initial value at baseline. Values are mean ± S.E.M. for n = 18 subjects/group. **p vs T0 and vs controls. Two-way ANOVA followed by Bonferroni’s post-hoc test was used for the analysis of differences among the groups; t-test was used for the variation analysis (Δ T1 − T0).

Figure 2

Evaluation of oxidative stress markers. (A) Bar graph shows the levels of malonyldialdehyde (MDA) in controls and cases at T0 and T1. (B) Bar graph shows the levels of 8-hydroxy-deoxyguanosine (8-OHdG) in controls and cases at T0 and T1. Delta (Δ) values are calculated by subtracting the final value at 3 months from the corresponding initial value at baseline. Values are mean ± S.E.M. for n = 18 subjects/group. *p < 0.05 vs control,**p < 0.01 vs T0; ***p < 0.001 vs T0. Two-way ANOVA followed by Bonferroni’s post-hoc test was used for the analysis of differences among the groups; t-test was used for the variation analysis (Δ T1 − T0).

Figure 3

Determination of inflammation parameters. (A and B) Analysis of pro-inflammatory cytokines TNF-α and IL-6 content (respectively) in plasma samples of controls and cases at T0 and T1. (C) Bar graph shows the plasma levels of the anti-inflammatory cytokine IL-10 in controls and cases at T0 and T1. Values are mean ± S.E.M. for n = 18 subjects/group. ***p < 0.001 vs T0 and vs control. ns = not significant. Two-way ANOVA followed by Bonferroni’s post-hoc test was used for the analysis of differences among the groups; t-test was used for the variation analysis (Δ T1 − T0).

Figure 4

Determination of plasma adiponectin as a marker of metabolic dysregulation. Bar graph shows the plasma levels of adiponectin in controls and cases T0 and T1. Delta (Δ) values are calculated by subtracting the final value at 3 months from the corresponding initial value at baseline. Values are mean ± S.E.M. for n = 18 subjects/group. *p vs T0 and vs control. Two-way ANOVA followed by Bonferroni’s post-hoc test was used for the analysis of differences among the groups; t-test was used for the variation analysis (Δ T1 − T0).

Figure 5

LAB’s rpoB sequences quantification. Bar graph shows rpoB copy number/ng of DNA in controls and cases at T0 and T1. Values are mean ± S.E.M. for n = 18 subjects. *p < 0.05, **p < 0.01 vs T0 controls and ***p < 0.001 vs T0 cases. Two-way ANOVA followed by Bonferroni’s post-hoc test was used for the analysis of differences among the groups; t-test was used for the variation analysis (Δ T1 − T0).