Canadian Health officials are sounding a warning over a very popular herbal supplement. In an official letter to healthcare providers, Health Canada announced that the agency is tweaking its official monograph for green tea extract to warn of a rare but potentially fatal side effect.
Green tea extract products sold in Canada must now bear a warning that reads, in part, “If you have a liver disorder, consult a health care practitioner prior to use. Stop use if you develop symptoms of liver trouble . . . and consult a health care practitioner.”
This newly required warning confirms that liver injury cases associated with green tea extract have been formally documented in Canada. The letter also recommends that green tea extracts, or supplements containing them, be recommended only for adults older than 18 years of age.
And for companies that produce products with green tea extract as an ingredient the agency asks that they either remove the extract completely or revise their labeling to reflect the agency’s recommendation that green tea extracts not be used by teenagers, children or infants.
How Common Is Green Tea Extract In Canada?
At last count, more than 2500 licensed “natural” products are on Canadian shelves. More than 550 of those are specifically marketed as weight loss remedies.
For most people, say officials, such products appear to be safe. But in the past decade, at least 11 cases of liver injury blamed, at least in part, on green tea extract have been documented.
Should U.S. Consumers Worry About Green Tea Extract?
For all the positive health benefits currently associated with green tea consumption, there have long been whispers of concern that extracts of it might not be quite as safe as green tea taken as a beverage. A recent study in the journal Calcified Tissue International, for example, finds that extracts have “negative effects on bones”, while research published in Biomedicine & Pharmacotherapy urges more study on their effect on the liver, especially in light of how popular green tea extract is as an “herbal” supplement.
A study in Cancer Prevention Research, which was also published recently, looked at data on more than 1000 women who participated in a year-long study examining green tea extract as a possible breast cancer preventative. The authors of this study say that women in the extracts group had “significantly higher” levels of certain liver enzymes than women in the placebo group.