Green Tea Extract Helps Reverse Fatty Liver Problems
James Meschino DC, MS, ROHP
An estimated 40 million Americans have some form of non-alcoholic fatty liver disease (NAFLD), which is strongly linked to obesity, type 2 Diabetes, insulin resistance and high cholesterol, according to the American Liver Foundation. Occasionally NAFLD is seen in patients with none of these risk factors. NAFLD is also known as hepatic steatosis due to the accumulation of fat in liver cells. Nearly 66% of Americans are currently overweight or obese and various studies suggest that 58–74% of obese adults and 23–53% of obese children are afflicted with NAFLD. It is normal for the liver to contain a small amount of fat, however if 5 to 10 percent of your liver’s weight is fat, you are considered to have fatty liver disease (1).
NAFLD Predisposes To More Serious Liver Pathologies
Excessive fat storage in the liver, as occurs in NAFLD, is considered to be the “first-hit” and was initially thought to be a relatively benign condition. However, studies now show that individuals with NAFLD are highly susceptible to secondary insults (i.e. second-hit) to the liver, such as those inducedby oxidative stress, which appear to accelerate the progression of hepatic steatosis toward more debilitating and advanced conditions such as non-alcoholic steatohepatitis (NASH), involving liver inflammation with fat accumulation, as well as cirrhosis and hepatocellular carcinoma – a highly malignant primary cancer of the liver.
NAFLD is often asymptomatic and its presence is often suspected by unexplainable elevations in liver enzymes in the serum, particularly ALT and AST, during an annual physical examination.
At present, there are no well-established treatments for hepatic steatosis beyond weight management or comorbidity management (e.g. diabetes management) Unfortunately, weight loss programs have shown poor long-term success rates, and thus other complementary therapeutic strategies to combat NAFLD are being explored.
Green Tea Catechins Shown To Reverse NAFLD and NASH
Animal studies have shown that green tea and/or its catechins can reverse NAFLD and NASH. Green tea and/or its catechins decrease intestinal fat absorption, lipogenesis (the conversion of carbohydrate into fat in liver cells), and fat storage while promoting fatty acid oxidation for energy. Thus, these potential mechanisms, acting individually or synergistically, may provide a possible explanation for the observed green tea extract mediated reductions in hepatic steatosis, hepatic lipid concentrations, and body weight. In the study by Bruno et al, obese mice fed green tea extract had 23–25% lower body weight than the obese controls, which was accompanied by improved serum ALT and AST serum levels (1).In this respect, green tea catechins have been shown to increase thermogenesis (burning fat and giving it off as heat to the environment) via several mechanisms, resulting in reduced body fat when catechin supplementation has been administered in animal and human studies (2).
Studies also show that supplementation with epigallocatechin gallate (EGCG), a unique catechin compound found in green tea and green tea extract, increased hepatic glutathione with a simultaneous reduction in hepatic lipid peroxidation. These findings suggest that green tea extract may be used as a potential dietary strategy help prevent and reverse NAFLD and NASH to varying degrees (1).
The study published in the September 2008 issue of the “Journal of Nutrition” examined the effects of EGCG on fatty liver symptoms in high-fat fed mice. Mice were treated with EGCG for four weeks. The study concluded that EGCG treatment helped to reverse fatty liver disease and helps to reduce inflammation. Another group of mice treated for 16 weeks had even more benefits. The study noted that the long-term treated mice had reduced body weight gain and fat percentage (1).
Lifestyle Prescription in NAFLD and NASH
For the estimated 40 million people in the U.S. with fatty liver disease it is recommended that they take prescribed medications (e.g. diabetes drugs, cholesterol-triglyceride lowering drugs), engaging in regular exercise, eating a low-fat, high fiber diet and abstaining from alcohol, which can all help their liver. Vitamin E supplementation at 800 IU has also been added to the recommended list of interventions shown to reverse liver damage in NASH (3). However, the research related to green tea indicates that anyone concerned with fat accumulation in his/her liver should also add drinking green tea to his/her daily routine.The typical cup of green tea contains 50 mg to 150 mg of polyphenols (antioxidants including catechins), and most experts suggest drinking 2-3 caps per day (1). Alternatively, taking a supplement with catechins derived from decaffeinated green tea, providing a daily dosage of 600 mg green tea extract (80% catechins, and 50% ECGC) can also be considered. This is the dosage range shown to enhance body fat reduction in human studies (2).
One final consideration involves supplementation with the flavonoid quercetin. Like green tea catechins, animal studies have shown that quercetin protects the liver from the development of NASH. One important study showed that mice fed a methionine-choline deficient diet (important for fat transfer out of the liver) developed liver steatosis, inflammatory cell accumulation, oxidative stress evaluated by the concentration of TBARS, and liver fibrosis, as evidenced by the staining of α-smooth muscle actin-positive cells in the liver. However, the mice that ingested quercetin (50mg/kg body weight) were partially or totally protected from these degenerative liver changes. The researchers conclude,“the data obtained suggest that attenuation of multiple profibrotic and proinflammatory gene pathways contributes to the beneficial effects of quercetin in mice with methionine-choline deficient diet-induced steatohepatitis”(4).
- Bruno S, Dugan CE, Smythe JA, DiNatale D, Koo SI. Green Tea Extract Protects Leptin-Deficient, Spontaneously Obese Mice from Hepatic Steatosis and Injury. J Nutr. 2008. 138 no. 2:323-331
- Nagao T, Komine Y, Soga S, Meguro S, Hase T, Tanaka Y, Tokimitsu I. Ingestion of a tea rich in catechins leads to a reduction in body fat and malondialdehyde-modified LDL in men. Am J ClinNutr 2005-81; 1:122-129. 2005
- Mercolin E, San-Miguel B, Vallejo D, Tieppo J, Marroni N, Gonzalez-Gallego, Tunon MJ. Quercetin Treatment Ameliorates Inflammation and Fibrosis in Mice with Nonalcoholic Steatohepatitis. Am J ClinNutr.vol. 142 no. 10:1821-1828