Gut-level Antiinflammatory Activities of Green Tea in Metabolic Syndrome

This study evaluates dietary green tea extract to improve gut health and inflammation in persons with metabolic syndrome and healthy adults. Participants will complete two phases of intervention in random order in which they will consume green tea extract or placebo for one month and then switch to the opposite treatment for an additional month.

Tea is the most abundantly consumed prepared beverage in the world. Green tea, containing catechins, exerts antiinflammatory activities. However, a fundamental gap exists concerning its intestinal-level targets that can prevent metabolic syndrome (MetS) development and progression. Studies in obese rodents indicate that green tea inhibits nuclear factor kappa-light-chain-enhancer of activated B cells (NFκB) activation by limiting gut-derived endotoxin translocation to the portal circulation and decreasing hepatic Toll-like receptor-4 (TLR4) pro-inflammatory signaling. The objective of this clinical investigation is to establish evidence-based recommendations for green tea, based on improvements in endotoxemia and restored gut barrier function, that promote optimal health. The hypothesis is that green tea catechins function to limit metabolic endotoxemia by ameliorating gut dysbiosis-mediated inflammation that otherwise provokes intestinal permeability. This will be tested by conducting a double-blind, placebo-controlled, randomized-order, crossover trial in MetS and healthy persons to examine the efficacy of green tea on metabolic endotoxemia. Each treatment will be one-month in duration and separated by a washout period. The anticipated outcomes are expected to be of significance, because they will advance a dietary strategy to help avert MetS complications attributed to metabolic endotoxemia by establishing antiinflammatory prebiotic and antimicrobial bioactivities of catechins that promote intestinal health.

Eligibility Criteria:
Inclusion criteria:

Individuals with ≥3 of the following established criteria for metabolic syndrome:

* Fasting glucose 100-126 mg/dL
* Waist circumference \>89/\>102 cm for females/males
* HDL-C \<50/\<40 mg/dL for females/males
* Triglyceride \>150 mg/dL
* Blood pressure \>130/85 mmHg

Healthy adults:

* Body weight 19-25 kg/m2
* Fasting glucose \<100 mg/dL
* HDL-C \>50/\>40 mg/dL for females/males
* Triglyceride \<150 mg/dL
* Blood pressure \<120/80 mmHg

Exclusion criteria:

* Concurrent tea consumption
* Use of dietary supplements, prebiotics, or probiotics
* Use of antibiotics or antiinflammatory agents
* History of liver disease, cardiovascular disease, hypertension (blood pressure \>140/90 mmHg), or cancer
* History of gastrointestinal disorders, chronic diarrhea, or surgeries
* Hemochromatosis
* Parkinson's disease
* Use of medications to manage diabetes, hypertension, or hyperlipidemia
* Use of antipsychotic medications \[Clozapine, lithium, Diazepam\]
* Use of blood thinning medications \[Warfarin\]
* Use of high blood pressure medications \[nadolol\]
* Use of monoamine oxidase inhibitors \[selegiline\]
* Alcohol consumption \>2 drinks/d
* Smoking tobacco
* Vegetarian
* Pregnancy, lactation, or recent changes in birth control use for women