by Renata Lorenc
Traditional Chinese Medicine (TCM) views the heart as the master of the body and the emperor of the organ networks. It generates chi, the vital energy of the body, and thus is the root of all life. Without a healthy heart, the body is fragile and stale. While many of us know that heart disease is rampant in the United States, we remain largely unaware of a powerful tool in its prevention: green tea. The heart protective effects of green tea can be attributed mainly to its antioxidant and anti-obesity properties, while other mechanisms play supporting roles. Each of these mechanisms will be discussed below in terms of TCM as well as Western medicine.
First, the antioxidant properties of green tea can be traced to its polyphenols, defined simply as groups of chemical substances in a plant. These polyphenols act as little superheros, taking the place of cells in danger of becoming oxidized and facing the oxidation themselves. In this way, they prevent the formation of free radicals – highly reactive atoms that can damage heart cells and, in TCM, leave cells incapable of generating chi. Research at the Graduate School of Medicine in Kyoto, Japan confirmed that green tea polyphenols can protect a heart from oxidative stress, as well as maintain good left ventricular function after ischemic arrest (restriction in the heart’s blood supply) and reperfusion (tissue damage caused when the blood supply returns). A study at Aichi Medical University in Japan similarly concluded that green tea is useful to ischemia-reperfusion hearts due to its ability to fight free radicals, and research at the University of Padova in Italy found that green tea extract prevented hypertension and targeted organ damage induced in rats, likely by scavenging free radicals.
There are four primary polyphenols in green tea and they are often collectively referred to as catechins, the most publicized of which is Epigallocatechin gallate, or EGCG. At Chungbuk National University in Cheongju, Korea, research suggests that EGCG prevents the development of left ventricular concentric hypertrophy (pathological thickening of the ventricle walls) due to high blood pressure and may be useful in preventing cardiac remodeling (changes in size, shape or function of the heart) in patients with diseases that strain the heart muscle. Furthermore, a 2004 review study at Complutense University of Madrid in Spain confirmed that catechins consumption decreases cholesterol absorption and plasma levels, scavenges free-radicals thereby inhibiting LDL oxidation, decreases systolic and diastolic blood pressures, and decreases body weight by interfering with fatty acid synthesis.
This ability of green tea to aid weight loss has been well-documented, and maintaining a healthy weight is intimately related to heart vigor. The tea’s anti-obesity properties can be attributed to its effects on lipid metabolism as well as its thermogenic (heat-producing) activity. A 2006 study at the University of Madras in Chennai, India found that the administration of green tea extract decreased cholesterol, triglyceride, free fatty acid levels and lipoprotein lipase activity in the heart of diabetic rats. Lipase is an enzyme that allows fat to be broken down – if its activity is decreased, cholesterol and triglycerides are removed rather than stored. A 2003 study at Roche Vitamins in Basel, Switzerland, a 2006 study at the University of Hawaii and a 2007 study at the University of Connecticut further confirm green tea’s lipid-lowering capabilities. In addition, a randomized, double-blind, placebo-controlled study at the University of Medicine in Berlin confirmed that EGCG alone has the potential to increase fat oxidation in men and may thereby contribute to the anti-obesity effects of green tea. In relation to thermogenesis (heat production that leads to increased metabolism), green tea, by containing both catechins and caffeine, may promote thermogenesis through inhibition of certain enzymes (catechol O-methyl-transferase and phosphodiesterase). In addition, tea catechins have anti-angiogenic (enlarging of blood vessels) properties that may prevent the development of excess weight. In TCM, weight loss involves limiting salty and sweet foods and increasing bitter and pungent foods. Green tea, a bitter food, is recommended.
These two health-giving properties of green tea — antioxidant activity and weight loss promotion — combine to additionally protect the heart in those with diabetes, as hyperglycemia-induced oxidative stress has been proposed as a cause of many complications of diabetes including cardiac dysfunction. Research at the University of Madras found that green tea extract ameliorates oxidative stress in the aorta and the heart of diabetic rats given streptozotocin (a chemical that is toxic to the insulin-producing cells of the pancreas). This suggests that green tea may be useful in the reversal of oxidative stress-induced cardiac dysfunction in diabetics. Another study at the University of Madras found that green tea improves the quality of heart collagen, also possibly therapeutic in the treatment of cardiovascular complications of diabetes.
Another mechanism by which green tea protects the heart is quelling inflammation. Research at the Children’s Hospital Research Foundation in Cincinnati, Ohio found that ECGC inhibits the expression of the interleukin-8 gene–a key gene involved in the inflammatory response. In TCM, inflammation is a result of consuming too many heating foods, such as meat, cooked oils, and processed sugar. The treatment involves consuming cooling foods, of which green tea, although often served hot, is a superstar due to its alkaloid content.
To conclude, green tea is an excellent guard of the emperor, protecting the heart through a wide range of mechanisms. In this way, green tea is highly effective in ensuring a strong, healthy body pulsing vibrantly with chi, the energy of life.
