Health Canada is strengthening its warning on green tea extract products – which are found in many over-the-counter weight-loss powders, pills and liquid supplements – over concerns of increased risk of liver damage.
According to Health Canada, there have been ongoing reports of serious liver injury worldwide, including a recent report in Canada. After conducting a review, the government body concluded that there may be a link between consuming green tea extract and “a risk of rare and unpredictable liver injury.”
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The risk is already identified in Health Canada’s Green Tea Extracts monograph, but following the review, it was determined the safety information could be stronger and as a result, the risk statement will be revised.
Another recommendation is that these products only be used by adults. As well, product license holders of these natural health products that are intended for children will be required to either remove the ingredient entirely from the product or change their label to indicate that the product is for adult use only.
Between 2006 and 2016, Health Canada had received 11 reports of suspected liver injury linked to the use of green tea extract products. However, only two had enough information to be fully assessed. It was concluded that these two cases of liver injury may have been related to the use of products containing the extract.
The World Health Organization Adverse Drug Reaction Database found 89 reports of liver injury associated with these products worldwide. However, Health Canada says there wasn’t enough information within the reports to do an in-depth assessment.
And while serious liver injuries with green tea extract products continue to be reported globally, Health Canada says they are rare.
Green tea extract products are authorized for sale in Canada and are often used in weight loss and as a source of antioxidants – the main antioxidant being EGCG.
Green tea drinks or food products are different than extract products because they usually contain less EGCG, so consuming green tea in any form won’t cause harm, Health Canada explains. The extract, however, contains a higher concentrated amount of EGCG, which is what Health Canada believes is causing liver injuries.
There are currently over 2,500 licensed natural health products containing green tea extract as a medicinal ingredient in Canada, the Health Canada Safety Review says. Over 550 of these products come with a claim related to weight-loss management as well.
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Health Canada says it will continue to monitor any safety information associated with green tea extract products and take “appropriate and timely action” if any other health risks are brought to light.
The American College of Gastroenterology also expressed their concerns over green tea extract in 2014.
While the correlation has yet to be understood, the college thinks there may be a genetic component that makes certain people more susceptible to the liver damage the supplements may cause, although they don’t know what it could be.
A 2013 study out of Baylor College of Medicine also found a link between the extract and acute liver failure.
While the antioxidant EGCG is thought to be beneficial, too much of it may be what leads liver injuries, researchers say.