Green Tea Supplement Side Effects Explained

Key studies warn about the insidious dangers of green tea supplement side effects. Can extract pills or tablets be harmful?

Take any healthy food excessively, it is likely to turn into a poison. Green tea supplements have been found to kill dogs at high doses.

Liver and Kidney Damage

One study found that green tea is good for you only when used in moderation. While it has been found to prevent heart disease and cancer, it could cause liver and kidney damage when consumed in very large quantities.

"People shouldn't be too alarmed by this, but those taking supplements may experience problems," says lead author Chung Yang of Rutgers, the State University of New Jersey.

"Up to 10 small cups of green tea a day is fine. Problems are likely in people who take supplements, which can contain up to 50 times as much polyphenols as a single cup of tea."

Liver Toxicity

Another study conducted by Bonkovsky reported 9 individuals suffering from liver toxicity after overdosing on supplements (at 10 to 29 milligrams per kilogram per day). 

Their symptoms disappeared when they stopped taking the pills, only to return when they started taking them again. A cause–effect relationship was suggested but not proven, as most of the products contained other ingredients in addition to green tea extract.

Tumour Growth

A laboratory study performed by the University of Mississippi found that high doses of green tea extract containing epicatechin gallate (ECG) may increase tumour growth. Low doses have been found to suppress new tumour growth with no observed side effects.

Researchers cautioned that results are preliminary. They also said the benefits of green tea are evidenced in those who drink the tea, but not necessarily those who consume supplements.

This green tea supplement side effects study was published in the Journal of Natural Products.

Tea Extraction Method

Dr. Stefan Siebrecht, managing director of Taiyo, alerted me to the dangers of many green tea products in the marketplace that uses organic solvent such as ethanol when making green tea extract. Here's a quote from his email:

There are different ways to extract green tea: Normally when you drink green tea you use water to infuse your tea, and then you drink it. By using hot water you extract only the water soluble polyphenols, caffeine, theanin and amino acids from the green tea. That is also happening every time when you drink green tea and that is the way green tea is used since thousands of years.

This is exactly the way how Taiyo is producing its Sunphenon® Green tea extracts. We use only pure water and make a double water infusion to extract the green tea leaves.

On the other side some producers of green tea Extracts use organic solvents to extract the green tea leaves. If you extract green tea leaves with organic solvents much more less polar and higher molecular weight green tea polyphenols are extracted.

These higher and less polar polyphenols are potentially liver toxic. Such green tea extracts caused serious liver damage in several cases in France and Poland so that the governments in both countries have forbidden the usage of green tea extracts as dietary supplements by law.

Such serious side effects did never appear after the consumption of water infused green tea extracts.

The problem is that the solvents extract MORE polyphenols out the green tea leaves and these organic solvents can be removed by using less energy, so that they are higher in polyphenols and very cheap, but potentially harmful.

Because of the low price such green tea extracts seem to be very attractive as a raw material source, but it is not natural to consume such less polar and higher molecular weight green tea polyphenols.

Taiyo’s Sunphenon® green tea extracts are the most natural water infused green extracts available on the market, as natural and safe as drinking a cup of green tea.

This high quality water based extraction is also the reason why SunPhenon green tea extracts are more expensive than many other green tea extracts. Quality and safety has its price.

How Much Is Too Much?

green tea extract side effectsAccording to the Mayoclinic, one cup of tea contains 80 to 100 milligrams of green tea polyphenols, depending on the strength and size of the cup. 

A green tea supplement can contain anywhere from 100 to 750 milligrams per tablet. Currently, there is no established recommended dose.

To decide how many green tea tablets to consume, follow the advice given by your green tea product or medical adviser.

Drinking green tea is safer. It is difficult to overdose. The United Kingdom Tea Council recommends up to 6 cups of tea a day.

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Joshua D. Lambert, Shengmin Sang, and Chung S. Yang (2007). Possible Controversy over Dietary Polyphenols: Benefits vs Risks. Chem. Res. Toxicol., 20 (4), 583 -585, 2007. 10.1021/tx7000515 S0893-228x(70)00051-6

Bonkovsky, H. L. (2006). Hepatotoxicity associated with supplements containing Chinese green tea (Camellia sinensis). Ann. Intern. Med. 144, 68-71.

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