Green-MED Diet: Gut Health & Heart Benefits

randomized-controlled-trial PMID: 35264213

Quick Summary: A new study found that the Green-Mediterranean diet, rich in plants and low in meat, improved gut health and heart health markers. This diet boosted the breakdown of branched-chain amino acids (BCAAs), which may help lower the risk of heart problems.

What The Research Found

The Green-MED diet, which includes green tea, a special aquatic plant called Mankai, and walnuts, changed the bacteria in people's guts. These changes were linked to better heart health, including weight loss and lower cholesterol. The diet seemed to help the body break down BCAAs, which are amino acids that can affect metabolism.

Study Details

Who was studied: 294 adults with belly fat and high cholesterol or other heart risk factors.

How long: 6 months.

What they took: Participants were split into three groups:

A control group following standard dietary advice.
A Mediterranean diet group (MED) with walnuts.
A Green-MED group (MED + green tea + Mankai).

What This Means For You

Eat More Plants: Focus on a diet rich in fruits, vegetables, and plant-based foods.

Consider Green Tea: Drinking green tea may help improve your gut health and heart health.

Limit Meat: Reducing your meat intake could be beneficial.

Gut Health Matters: A healthy gut is linked to better overall health, including heart health.

BCAA Breakdown: The study suggests that diet can influence how your body handles BCAAs.

Study Limitations

Short Study: The study only lasted 6 months, so we don't know the long-term effects.

More Research Needed: More studies are needed to confirm these findings and understand the exact role of Mankai.

Self-Reported Data: The study relied on people reporting what they ate, which can be less accurate.

Specific Population: The study focused on people with specific health issues, so the results may not apply to everyone.

Key Findings

The Green-MED diet, enriched with polyphenol-rich green tea, Mankai aquatic plant, and walnuts, significantly altered gut microbiome composition compared to the traditional Mediterranean (MED) diet. Key microbial changes included enrichment of Prevotella (p < 0.05) and reduced Bifidobacterium (p < 0.05), alongside shifts in enzymatic functions: increased branched-chain amino acid (BCAA) degradation pathways and decreased BCAA biosynthesis. These microbiome changes were associated with greater reductions in body weight (-2.3 kg vs. MED’s -1.5 kg), LDL cholesterol, and liver fat. Adherence to Green-MED correlated with microbiome shifts, which mediated 14–30% of the diet’s cardiometabolic benefits.

Study Design

Type: Randomized controlled trial (DIRECT-PLUS trial, ClinicalTrials.gov NCT03020186).
Participants: 294 adults with abdominal obesity/dyslipidemia.
Intervention: 6-month dietary intervention with three groups:
Control (standard dietary guidelines),
MED (isocaloric Mediterranean diet + 28g/day walnuts),
Green-MED (MED + 3–4 cups/day green tea + 100g frozen Mankai shake/day).
Methods: Gut microbiota analyzed via 16S rRNA sequencing (all samples) and shotgun metagenomics (subset). Cardiometabolic markers (weight, LDL, insulin sensitivity) measured at baseline/endpoint.

Dosage & Administration

Walnuts: 28g/day in both MED and Green-MED groups.
Green tea: 3–4 cups/day (unsweetened, polyphenol-rich).
Mankai: 100g frozen Mankai plant-based green shake/day.
Administration: Dietary components were self-administered as part of structured meal plans.

Results & Efficacy

Microbiome Changes:
Green-MED increased Prevotella abundance (p < 0.05), linked to plant-based diets, and reduced Bifidobacterium (p < 0.05), associated with lower BCAA biosynthesis capacity.
Enzymatic pathways for BCAA degradation were elevated in Green-MED (p < 0.05), while BCAA biosynthesis pathways declined.
Cardiometabolic Outcomes:
Green-MED led to greater weight loss (-2.3 kg vs. -1.5 kg in MED) and reduced LDL cholesterol (-6.4 mg/dL vs. -2.3 mg/dL).
Liver fat and insulin resistance improved significantly in both MED groups vs. control (p < 0.05).
Mediation Analysis: Microbiome changes explained 14–30% of the association between Green-MED adherence and improved cardiometabolic markers (p < 0.05 for mediation effect).

Limitations

Short Duration: 6-month follow-up may not capture long-term microbiome-cardiometabolic interactions.
Microbiome Profiling: 16S rRNA sequencing lacks species-level resolution; shotgun analysis was limited to a subset.
Adherence Measurement: Self-reported dietary compliance introduces potential bias.
Causality: Observational mediation analysis cannot confirm direct causal links between microbial shifts and outcomes.
Population Specificity: Results limited to individuals with abdominal obesity/dyslipidemia; broader applicability untested.

Clinical Relevance

The Green-MED diet’s emphasis on polyphenol-rich plants (green tea, Mankai) and reduced meat intake may enhance gut microbial pathways that degrade BCAAs, potentially reducing their metabolically harmful effects. For supplement users, this suggests that diet quality influences BCAA metabolism via the microbiome, though direct supplementation effects were not studied. The findings support combining plant-based diets with probiotic/prebiotic strategies to optimize cardiometabolic health. However, further research is needed to isolate Mankai’s role and validate microbiome-targeted interventions.

Takeaway: Prioritizing plant-based polyphenols and minimizing animal protein may improve gut microbial function, indirectly enhancing BCAA metabolism and cardiometabolic outcomes.