Green Tea (Camellia sinesis) has been cultivated for centuries, beginning in India and China. Today, green tea is the most widely consumed beverage in the world, second only to water. Hundreds of millions of people drink green tea every day. Green tea is made from the unfermented leaves (black tea is made from the fermented leaf) and reportedly contains the highest concentration of the powerful medicinal antioxidants called polyphenols. Antioxidants are substances that fight free radicals -- damaging compounds in the body that change cells, damage DNA, and even cause cell death. Many scientists believe that free radicals contribute to the aging process as well as the development of a number of health problems, including cancer and heart disease. Antioxidants such as polyphenols in green tea can neutralize free radicals and may reduce or even help prevent some of the damage they cause.
Effects on Mortality Rate due to Cardiovascular Disease:
A study was published in the Journal of the American Medical Association which concluded that "Green tea consumption is associated with reduced mortality due to all causes and due to cardiovascular disease." It was shown that participants who consumed 5 or more cups of tea per day had a 16 percent lower risk of all-cause mortality and a 26 percent lower risk of cardiovascular disease ("CVD") than participants who consumed less than one cup of tea per day. That study also stated that "If green tea does protect humans against CVD or cancer, it is expected that consumption of this beverage would substantially contribute to the prolonging of life expectancy, given that CVD and cancer are the two leading causes of death worldwide.” Apparently researchers estimate that the rate of heart attack decreases by 11% with consumption of 3 cups of tea per day.
Improving cholesterol levels:
Green tea has been found to lower the “bad” cholesterol levels and to prevent their harmful effects on the body. Research shows that green tea lowers total cholesterol and raises HDL ("good") cholesterol in both animals and people. One population population based clinical study found that men who drink green tea are more likely to have lower total cholesterol than those who do not drink green tea.
Results from one animal study suggest that those antioxident polyphenols in green tea may block cholesterol from being absorbed in the intestine and also help the body get rid of cholesterol. In another small study of male smokers, researchers found that green tea significantly reduced blood levels of harmful LDL cholesterol.
Researchers in a study appearing in the Journal of the American College of Surgeons noted that green tea may prevent the oxidation of LDL cholesterol (the "bad" type), which, in turn, can reduce the buildup of plaque in arteries.
Lessens Cognitive Impairment:
Green tea is good for the brain and preventing the progressive cognitive decline that occurs with aging. A study from the American Journal of Clinical Nutrition concluded, "A higher consumption of green tea is associated with a lower prevalence of cognitive impairment in humans."
Good for Weight Loss:
Clinical studies suggest that green tea extract may boost metabolism and help burn fat. One study found that the combination of green tea and caffeine improved weight loss and maintenance in people who were overweight and moderately obese. Some researchers think that substances in green tea known as catechins are responsible for the herb's fat-burning effect. A study published in the January, 2005 edition of the American Journal of Clinical Nutrition concluded "Daily consumption of tea containing 690 mg catechins for 12 wk reduced body fat, which suggests that the ingestion of catechins might be useful in the prevention and improvement of lifestyle-related diseases, mainly obesity."
Prevention and Reduction of Rheumatoid Arthritis:
According to a Case Western Reserve University School of Medicine study published in the Proceedings of the National Academy of Sciences, antioxidants in green tea prevent and reduce the severity of rheumatoid arthritis. . Research suggests that green tea may help osteoarthritis as well by reducing inflammation and slowing the breakdown of cartilage.
Positive Effects for Smokers:
Researchers at Yale University School of Medicine weighed in on the health benefits of Green Tea in a review article that looked at more than 100 studies on green tea. They pointed to what they called an "Asian paradox," which refers to lower rates of heart disease and cancer in Asia despite high rates of cigarette smoking. They theorized that the 1.2 liters of green tea that is consumed by many Asians each day provides the high levels of polyphenols and other antioxidants that cause this protective health benefit. Researchers who have discovered that chemicals in green tea shut down one of the key molecules that tobacco relies upon to cause cancer. I don’t advise smoking at all but if someone is addicted and smokes regularly it may be a good idea for them to consume green tea to prevent the harmful effects.
Beneficial Effect on Cancer Outcomes:
Several clinical studies have shown that green tea may help protect against cancer. Early clinical studies suggest that the polyphenols in green tea may play an important role in the prevention of cancer. Researchers also believe that polyphenols help kill cancerous cells and stop them from growing.
One study of particular note was done on 472 women with various stages of breast cancer, researchers found that women who drank the most green tea had the least spread of cancer. It was especially true in premenopausal women in the early stages of breast cancer. They also found that women with early stages of the disease who drank at least 5 cups of tea every day before being diagnosed with cancer were less likely to have the cancer come back after they finished treatment. However, women with late stages of breast cancer had little or no improvement from drinking green tea.
In one study that compared people with and without bladder cancer, researchers found that women who drank black tea and powdered green tea were less likely to develop bladder cancer. A follow-up clinical study by the same group of researchers revealed that people with bladder cancer -- particularly men -- who drank green tea had a better 5-year survival rate than those who did not.
Green tea has been used traditionally to control blood sugar levels. Animal studies suggest that green tea may help prevent the development of type 1 diabetes and slow the progression once it has developed. In people with type 1 diabetes, their bodies make little or no insulin, which helps convert glucose or sugar into energy. Green tea may help regulate glucose in their body.
A few small clinical studies have found that taking a green tea extract daily lowered the hemoglobin A1c level (a measure of how uncontrolled a persons blood sugar is over past 3 months) in people with borderline diabetes.
Is Green Tea Safe for Everyone?
Green Tea contains active substances that can trigger side effects and interact with prescription drugs, supplements, and or other herbal medications. For these reason, if you have a medical condition or are on medication, you should only take green tea under the supervision and advice of a licensed medical practitioner.
As you can see from the number of studies above, Green tea is an amazing gift for our health given to us by Hashem. It is a strong tool for prevention of many of the diseases that most plague our society today. Certainly a cup or 2 of green tea a day may very well keep the doctors away!
Dr. Anders Nerman, ND
Dr. Anders Nerman, N.D. is a Naturopathic Doctor with an Integrative Family Medical practice in Wolfson Medical Center in Jerusalem, Israel. For more visit www.drnerman.com or call 972-54-427-8667.