Recently, a man in Western Australia was diagnosed with liver failure after taking two supplements, one was a protein powder containing green tea extract while the other was a fat loss supplement containing garcinia cambogia. In another article, we will look at whether or not garcinia cambogia is toxic, whereas this article will focus on Green Tea Extract.
What is Green Tea Extract?
Green tea extract is simply concentrated green tea. Both green tea and green tea extract has been shown to offer a variety of benefits for health indices including cholesterol levels, blood pressure and fasting blood glucose. You’ll also often find green tea extracts in fat loss support supplements such as fat burners and weight loss protein powders thanks to its ability to boost fat burning and fat metabolism. Most of the benefits of green tea are due to the water soluble polyphenols present in the tea known as catechins. These are leeched from the leaves into the tea during normal preparation, and concentrated during the production of green tea extract.
Green Tea Extract in Supplements
As previously mentioned, green tea extract is often found in a variety of supplements, most commonly in fat burners and fat loss or weight loss protein powders. Fat burners are supplements which contain a variety of ingredients which can help support weight loss via a variety of mechanisms including appetite suppression, fat metabolism and overall metabolism boosts as well as energy support. Weight loss protein powders on the other hand are simply protein powders which also contain some fat loss ingredients. The level of these fat loss ingredients will often be lower than that of what’s seen in fat burners. As green tea naturally contains caffeine, green tea extracts may also be found in pre workout supplements, which are supplements consumed before training which can boost training performance and results. One of the supplements in question that was involved in this liver failure case was a weight loss protein powder containing green tea known as Hydroxyburn Elite by BSc Body Science.
Is Green Tea Extract Toxic to the Liver?
Interestingly enough, green tea extract can be both beneficial and harmful to the liver. Green tea consumption has been shown to be helpful in reducing the risk of developing liver cancer due to its ability to protect the liver against a range of toxins and issues such as oxidative stress, inflammation, smoking and alcohol.
However, green tea extract at high doses have been shown to be toxic in animals. Symptoms involve vomiting, diarrhoea and even death. However, these doses were extremely high, around 500-2000mg/kg of body weight of catechins or equivalent to 2800 cups of green tea consumed by a 70kg person. There have been human case studies which have shown liver damage with lower levels of green tea extract consumption. However, cause and effect is hard to pin due to the presence of a variety of other ingredients in the supplements consumed. The most recent case of liver toxicity seems more like a case of bad luck in an individual who is more susceptible and who was also taking other fat loss supplements.
So what are the key points about green tea and green tea extract and liver toxicity?
- Green tea is extremely safe to drink
- Green tea extract is mostly safe in the majority of circumstances
- In susceptible or sensitive individuals, no dose is seen as safe
- The higher the dose of green tea extract, the greater the risk
Green Tea Extract Dosage Recommendations
Green tea extract benefits for fat loss and obesity occur somewhere around 400-500mg. Higher supplemental doses of 800mg have been shown repeatedly to be safe to consume. Single doses of a particular polyphenol, EGCG (epigallocatechin gallate) have been tolerated at 1600mg. An average 70kg male will need 7.9g of green tea extract or 1.9g x 3 times daily for acute toxicity to occur. As previously mentioned though, there are no safe doses for those who are more sensitive or susceptible to the negative effects of green tea extract.
Should I Be Worried About Green Tea Extract?
From all the evidence currently available, the answer to the above question is no. There isn’t really a need for concern regarding the consumption of green tea extract for the majority of consumers. Most supplements will contain respectable and generally safe levels of green tea per recommended serve, however it’s always advisable to consult your doctor before the commencement of any supplement. There’s never been any health issues reported for any of the BSc Body Science products in over 14 years, so the case is definitely rare and an anomaly. Having said that, with any ingredient, naturally derived or otherwise, it’s important to stick to the recommended doses and to have a break of use after every 4-8 weeks.1. Smith RJ, Bertilone C, Robertson AG. ‘Fulminant liver failure and transplantation after use of dietary supplements.’ Med J Aust. 2016 Jan 18;204(1):30-2.
2. Li Y, et al Green tea consumption, inflammation and the risk of primary hepatocellular carcinoma in a Chinese population . Cancer Epidemiol. (2011)
3. Ullmann U, et al Plasma-kinetic characteristics of purified and isolated green tea catechin epigallocatechin gallate (EGCG) after 10 days repeated dosing in healthy volunteers . Int J Vitam Nutr Res. (2004)
4. Ullmann U, et al A single ascending dose study of epigallocatechin gallate in healthy volunteers . J Int Med Res. (2003)