From Microbiota to Vessels: How the Mediterranean Diet Fights Metabolic Syndrome

Nutrients has published an editorial review of the special issue "The Mediterranean Diet (MedDiet) and Metabolic Syndrome (MS)". The authors have collected 6 reviews and 7 original studies - from children to the elderly, from clinical randomized trials to population cross-sections - and show that MedDiet systematically hits the key nodes of MS (central obesity, hyperglycemia, dyslipidemia, hypertension), and mechanistically rests on mitochondria, microbiota and anti-inflammatory pathways.

Background

• Metabolic syndrome (MS) is a massive “risk node”. According to meta-analyses, the global prevalence of MS fluctuates between ~12-31% depending on the criteria (ATP III, IDF, JIS) and is especially high in the WHO Regions of the Americas and Eastern Mediterranean. This explains the interest in simple, scalable lifestyle interventions.
• The Mediterranean diet (MedDiet) has a rare “double leg”: RCTs + mechanisms. In the PREDIMED trial and its reanalysis (NEJM, 2013/2018), the MedDiet with olive oil or nuts reduced the risk of major CV events in high-risk individuals - one of the most compelling clinical cases for dietary patterns.
• Why MedDiet logically hits the components of MS. Modern studies link its benefits to:
  • Gut microbiota (for example, the “green” MedDiet in RCTs was associated with microbiome restructuring and improved cardiometabolic health).
  • Reduction of vascular stiffness and improvement of endothelial function (systematic reviews).
  • Antioxidant-anti-inflammatory action and influence on mitochondria (reviews of the special issue).
• How is adherence to MedDiet measured? For adults - a short validated questionnaire MEDAS (14 items); for children and adolescents - the updated KIDMED 2.0. These tools allow standardization of studies and tracking of implementation in the clinic/population.
• Why the Nutrients Special Issue (2025) Was Necessary. Despite its strong clinical basis, the effect of MedDiet in MS depends on age, context, and the “little things” of practice (preparation technology, combination with physical activity, social factors). The editorial review collects reviews and original papers - from childhood lipids to inflammation biomarkers and quality of life - to link molecular mechanisms to real-world implementation scenarios.
• Practical fork in the road. Further progress is expected from long-term RCTs, "omics" approaches to personalization, and validated adherence biomarkers - to understand who gets which version of MedDiet (including "green-Med") and in which environment brings the greatest benefit against MS.

What is this publication?

This is an editorial for a special issue: not a single new study, but a “map of the terrain” that briefly discusses the contribution of each included paper and outlines where to go next. In the introduction, the authors remind us that interest in MedDiet is fueled by large clinical data (including the reanalysis of PREDIMED) and growing mechanisms at the cellular and molecular level.

What's new and important in this issue

1) Mechanisms of action: not only "olive oil is good for you"

• Microbiota and the “green” MedDiet. A 2022 RCT linked the “green MedDiet” to microbiome remodeling that went hand in hand with improvements in cardiometabolic markers. Conclusion: Part of the benefit is via the “gut-metabolic” axis.
• Arterial stiffness: A systematic review of 16 studies found an inverse association between MedDiet adherence and pulse rate and augmentation index, early markers of vascular aging.
• Mitochondria, Oxidative Stress, and Polyphenols. Mitochondria Review Highlights: MedDiet's Antioxidant and Anti-Inflammatory Components Improve Mitochondrial Efficiency, Mitophagy, and Biogenesis.
• Quality of life and sexual function. A separate review suggests that in the setting of MS, MedDiet is associated with better sexual health outcomes through vascular and anti-inflammatory effects.

2) Original data: from children's lipids to sour bread

• Children with primary dyslipidemia: Even a moderate increase in adherence to the MedDiet (KIDMED update) reduced LDL and non-HDL - an argument for early intervention.
• Epicardial fat in children. EAT thickness in rural Spanish schoolchildren was strongly correlated with components of MS (BMI, LDL, blood pressure) - a potential early marker of risk.
• MedDiet + strength isokinetics in MS. In RCTs, diet alone and in combination with training selectively changed proinflammatory cytokines (resistin ↓, adiponectin ↑), while body composition changed more modestly.
• Unexpected about bread. Short fermentation of sourdough bread reduced PAI-1 and sICAM in people with MS more than long fermentation, with unchanged microbiota - a hint at the subtle role of preparation technologies.
• Religious Lenten Diet vs. Intermittent Fasting. Nuns (plant-based MedDiet with religious fasting) had increased total antioxidant capacity, laywomen on the 16:8 regimen had increased glutathione levels: different but complementary antioxidant profiles.
• Vulnerable groups. In the low-income Portuguese sample, quality of life was more "pulled" by physical activity and education; adherence to MedDiet without these factors did not produce a noticeable shift - dietetics must be embedded in context.
• Large population of adults (n > 3400). Higher adherence to MedDiet - lower chance of having MS and its components; better levels of BP, glycemia, TG and HDL. Cross-sectional study, but the signal is consistent.

Why is this important?

• MedDiet works on a “broad front.” From microbiota and mitochondria to vascular function and inflammation, the dietary pattern has “bridges” to each component of MS. This explains why the effect is visible at different ages and conditions.
• Practice benefits from nuances. Preparation technologies (sourdough example), combination with physical activity and cultural context (religious fasts, income, education) change the response - and this can be managed in prevention programs.

What This Means "For Life" (And What to Expect Next)

• The MedDiet Basic Plate - vegetables/fruits, whole grains, legumes, nuts, olive oil; fish regularly; less red/processed meat and sugar. For people with MS, this is the first line of lifestyle therapy.
• Strength is in consistency. Add movement (strength/aerobic), monitor sleep and stress, consider your wallet and culture: a diet is easier to maintain if it is embedded in reality.
• Scientific agenda: The authors call for more long-term RCTs, "omics" approaches, and validated adherence biomarkers to more accurately personalize nutrition.

Restrictions

The special issue brings together studies of different calibers; several trials are small and short, and Mediterranean samples predominate (limiting the transferability of results outside the region). But the overall vector - against MS - is clearly visible.

Source: Giacco A., Cioffi F., Silvestri E. Mediterranean Diet and Metabolic Syndrome (editorial, special issue of Nutrients, vol. 17, no. 14, 2025). https://doi.org/10.3390/nu17142364