Metabolic syndrome is a group of conditions that often occur simultaneously and lead to an increased risk of developing heart disease, stroke and diabetes. The contributing factors (symptoms) include high blood pressure, high insulin levels, abnormal cholesterol levels and excess abdominal fat. Because obesity and related diseases are at pandemic levels, the International Diabetes Federation has adopted the following definition for metabolic syndrome.
The International Diabetes Federation worldwide definition of metabolic syndrome(2006):
Abdominal obesity (defined by American Heart Association as elevated waist circumference:
Men — Equal to or greater than 40 inches (102 cm) with ethnicity specific values
Women — Equal to or greater than 35 inches (88 cm) waist circumference# with ethnicity specific values)
AND any two of the following:
· Raised triglycerides : >150 mg/dL (1.7mmol/L), or specific treatment for this lipid abnormality.
· Reduced HDL cholesterol: < 40 mg/dL (1.03 mmol/L) in males
< 50 mg/dL (1.29 mmol/L) in females, or specific treatment for this lipid abnormality
· Raised blood pressure : systolic BP > 130 or diastolic BP >85 mm Hg, or treatment of previously diagnosed hypertension.
· Raised fasting plasma glucose 
FPG)>100 mg/dL (5.6 mmol/L), or previously diagnosed type 2 diabetes. If FPG >5.6 mmol/L or 100 mg/dL, OGTT Glucose tolerance test is strongly recommended but is not necessary to define presence of the Syndrome.
# If BMI is >30 kg/m², abdominal obesity can be assumed and waist circumference does not need to be measured
A diagnosis of metabolic syndrome is not made based on a patient having only one of the symptoms. But having any one of these factors increases the risk of developing metabolic syndrome. Having more than one symptom further increases the risk.
Obesity
Obesity of people of all ages has reached pandemic levels worldwide during the past few decades. It is characterized by having a Body Mass Index (BMI) of at least 30.0. Clinical studies show that EGCG has numerous effects in the body that lead to weight loss.
Green tea and green tea extract prevent fat from being made in cell lines, animal models, and humans. EGCG, the predominant antioxidant in green tea is generally proven to help prevent obesity. The most significant actions of EGCG in preventing obesity are the potential to inhibit proteins and enzymes that make fat and to promote proteins and enzymes that minimize fat production.
Minimized carbohydrate absorption can help prevent weight gain. A combination of green, black and mulberry tea extracts were given to healthy subjects as a blend. A high carbohydrate and high fat meal eaten while drinking the tea significantly prevented carbohydrate absorption.1
It has been shown that EGCG reduces fat and lowers lipids in plasma in animals. The mechanisms in play are thought to be the slowing fat production, the breakdown of fats and creating heat within cells; which uses fat as fuel.
Some studies have revealed that drinking green tea prior to physical activity aids in fat burning and increasing metabolic rates. Current studies are investigating how EGCG enhances fat burning on a molecular level. For example, researchers at the National Institute of Health’s National Center for Complementary and Alternative Medicine are learning how EGCG can assist insulin in creating favorable metabolic and vascular processes.
Diabetes
Green tea is widely accepted as a beverage that contains several antioxidants and other molecules that enhance insulin production. One laboratory study isolated EGCG, ECG, tannins, caffeine and theaflavins to measure the individual ability of each to increase insulin-enhancing activities. They found that EGCG and ECG significantly increased insulin production but the other molecules did not.2
They also looked at the effect of popular tea mix-ins and found lemon did not affect insulin activity, but soy milk, 2% cow milk and non-dairy creamers significantly reduced insulin activity. The most dramatic reduction in insulin activity was observed when adding 5 grams of cow milk per cup of tea (33% reduction) and adding 50 grams per cup of tea (90% reduction).
Other clinical trials show that green tea, more specifically EGCG in the tea, can assist or even act as a substitute for insulin, bringing about positive effects on metabolism and the vascular system.
One study showed that EGCG may play a role in Type II Diabetes prevention and treatment.3
Next, scientists set out to see if similar effects occur in humans when they are given supplemental EGCG.4 They gave a group of obese men EGCG supplements for 8 weeks and found no enhancement of insulin activity. Could it be that the EGCG must be delivered to the body in green tea? They found a modest reduction in blood pressure and study subjects reported a positive effect on their mood. More studies need to be conducted to learn more about the effects of EGCG in humans.
The Role of Green Tea in Prevention and Treatment of Metabolic Syndrome
Fortunately, metabolic syndrome and its contributing factors can be prevented or reversed simply by making some lifestyle changes. Along with daily exercise and eating 5 servings of fruits and vegetables per day, adding a few cups of green tea can help regulate insulin levels and metabolism, reduce bad cholesterol and assist in weight loss.
1Green tea supplementation ameliorates insulin resistance and increases glucose transporter IV content in a fructose-fed rat model. Wu LY, Juan CC, Hwang LS, Hsu YP, Ho PH, Ho LT.
Eur J Nutr. 2004. 43(2):116-24. Epub 2004 Jan 6.
2Tea Enhances Insulin Activity. Richard A. Anderson and Marilyn M. Polansky. J. Agric. Food Chem. 2002. 50(24), pp 7182–7186.
3Proposed mechanisms of (-)-epigallocatechin-3-gallate for anti-obesity. Moon HS, Lee HG, Choi YJ, Kim TG, Cho CS. Chem Biol Interact. 2007. 167(2):85-98. Epub 2007 Feb 20.
4Brown AL, Lane J, Coverly J, Stocks J, Jackson S, Stephen A, Bluck L, Coward A, Hendrick H. Br J Nutr. 2009..10(6):886-94. Epub 2008 Aug 19.
