The green tea plant originated in China and is now being cultivated and consumed worldwide due to the pleasing taste and the many health benefits of green tea. Although green and black tea are both of the same species (Camellia sinensis), green tea is higher in plant compounds called polyphenols which can be attributed to the plant’s antioxidant and anticancer properties.
The reason green tea contains high amounts of polyphenolic substances is because, unlike black tea which uses fermented tea leaves, the tea leaves for green tea are only lightly steamed which keeps the polyphenolic compounds intact. Green tea can be consumed as a steeped beverage or taken as an extract in pill or liquid form.
Claims for Health Benefits of Green Tea
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Lowers risk of cardiovascular disease
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Aids in weight loss
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Anti-cancer/anti-tumor
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Lowers cholesterol
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Immune enhancement
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Improves insulin resistance
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Anti-anxiety
Scientific Support for Theory Behind the Health Benefits of Green Tea
Green tea extracts are associated with increased weight loss due to their ability to induce thermogenesis. This implies that green tea can increase the generation of body heat that is associated with absorption and metabolism of food. The active ingredients in green tea responsible for the increase in metabolism are caffeine and a catechin compound called EGCG.
In addition to being a valuable tool for weight loss, green tea is also good for you. Due to the polyphenol and catechin content, it has been shown to have anti-cancer, antioxidant properties much higher than vitamin C or E and it is able to lower cholesterol. Green tea is also useful for stress and anxiety due to its theanine content, a compound that has a calming effect on the nervous system.
Scientific Support for Health Benefits of Green Tea
There are two studies that did not show any benefit for green tea and weight loss; however, the conclusion of several literature reviews, seven human studies and two animal studies on green tea and was that green tea does indeed have a positive effect on weight loss for its ability to increase metabolism and fat breakdown and through inhibition of fat formation. Most of these effects are due to the ECGC component as well as the combined effect of ECGC and caffeine.
In addition to the positive literature reviews on green tea and weight loss, there are also reviews highlighting its use to lower cholesterol, protect against cancer and decrease stress.
Green Tea Safety
Green tea is safe for most adults when used in moderate amounts. It is not associated with any significant side effects or toxicity. As with any caffeine containing beverage,
overconsumption of green tea can produce a stimulant effect causing nervousness, insomnia, irritability and anxiety. The amount of caffeine needed to produce these results can vary from person to person. Green tea contains about 20 mg of caffeine per cup (ranges from 8-30 mg) as opposed to the 85-100 mg consumed in a cup of coffee.
Green tea is contraindicated for pregnant and lactating women and people who are sensitive to caffeine. It is also not recommended before surgery or for people on blood thinning medication as it contains small amounts of vitamin K. There are a handful of case reports of acute liver failure in patients taking a concentrated green tea extract. One research article on this topic stated that the liver failure could have been an allergy to green tea extract or that the extract may have been contaminated.
Contamination of green tea (and black tea) is a real concern. Analyses of some of the green tea coming out of China, has shown lead contamination of tea leaves partly from using old processing equipment. Fluoride and aluminum are also common contaminants in tea coming from India and China as a result of the soil and air pollution in those areas. Therefore, you may wish to avoid tea that is grown in these areas even if the tea says “Certified Organic” which does not mean that it is free of heavy metals.
With this in mind it is wise to choose green tea extracts that are certified to be free of heavy metals or to buy green tea grown in Japan. Most tea is grown in China, India, Bangladesh and Pakistan but tea industry insiders say that the highest grades of tea are grown in Japan—and are reserved for the Japanese. The lower grades of tea are distributed around the world to consumers like Americans who don’t know any better.
Doses for Health Benefits of Green Tea
Green tea standardized extracts in pill form should contain 80% total polyphenols and 55% epigallocatechin gallate which equals about 300-400 mg of polyphenols. Green tea supplements should be taken 3 times a day before meals or away from food. One cup of green tea equals 100-300 mg of polyphenols. With this in mind, 3-4 cups of tea may need to be consumed each day to achieve weight loss benefits equal to taking the extract form.
Cost of Green Tea
The cost of drinking green tea can be anywhere from $10-40 dollars a month. The cost of capsules containing standardized extracts can be anywhere from $20-35 dollars a month depending on the concentration of polyphenols and EGCG.
Green tea not only aids with weight loss, but it has a powerful effect on your overall health in terms of increasing your immune system, and decreasing cardiovascular disease and insulin resistance. Japanese people have the longest lifespan in the world. This is paradoxical when you consider that they can be heavy drinkers and smokers and they consume high amounts of fish contaminated with mercury.
Some scientists believe that the high consumption of green tea protects the Japanese from their less than perfect health habits. I (Dr. Pearsall) have spent time in Japan and I’ve noticed that the Japanese people eat plenty of food but everyone is very thin.
Instead of coffee in the morning, consider switching to green tea. I recommend green tea as a general health tonic to everyone but especially those who want to attain their ideal weight. You can take green tea as an extract, or tea. The best tea I've found is Matcha Organic Green Tea which is a whole leaf powder of the highest quality green tea in the world.
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