Despite New York Times' warning, liver damage from green tea extract is rare

Just when we thought the week of media hell was over, week two started.

Sunday morning's front cover of the New York Times told consumers, "Spike in Harm to Liver Is Tied to Dietary Aids."

Author Anahad OConnor quoted data from the Drug-Induced Liver Injury Network, which found 20% of product-induced liver damage were linked to supplements.

The article said investigators looked at 845 patients with severe, drug-induced liver damage who were treated at hospitals in the network from 2004 to 2012. In 2004, supplements accounted for 7% of the 115 severe cases, and from2010 to 2012, 20% of the 313 cases recorded came from supplements.

Natural Products Insider's request to the Drug-Induced Liver Injury Network did not produce data, but if The New York Times' numbers are correct, that means less than one-quarter of the liver cases came from supplements. The title of this article could easily have been "Prescription Drugs cause 80% of Liver Disease Cases." But it wasn't.

Like other articles, this New York Times  piece said, "the supplement business is largely unregulated," which isn't true. It also said, "Usually the agency must wait until consumers are harmed before officials can remove products from stores," which also is not true. Lastly, it said "the supplement industry operates on the honor system." Anyone testing and retesting to meet required GMPs (good manufacturing practices) knows this isnt true. 

Yes, there are bad apples in the supplement industry. Duffy MacKay from the Council from Responsible Nutrition (CRN) was quoted in the New York Times  article as saying criminal operations are the fringe of the industry, and multivitamins, minerals, probiotics and other supplement categories aren't linked to a high number of adverse events.

And the article quotes Dr. Victor Navarro, the chairman of the hepatology division at Einstein Healthcare Network in Philadelphia, who said a majority of supplements are generally safe, and most liver injuries are caused by prescription drugs.

Still, the article focuses on bodybuilding and weight management supplements as the biggest culprits, calling out products spiked with steroids and those that contain green tea extract. A researcher quoted in the article said a high level of the catechins found in green tea could be toxic to the liver.

In 2008,the U.S. Pharmacopeia (USP) reported a systemic review of 216 safety reports on green tea products from 1966 to 2007 found safety issues are not significant when green tea extract products are used and formulated appropriately (Drug Saf. 2008;31(6):469-84). However, USP acknowledged the potential for green tea extract to cause hepatotoxicity and  encouraged a caution statement on product labels.

USP later reversed its recommendation of label warning because it could not find a direct risk between green tea extract and liver damage after it continued its research, according to Claudia Costabile, USP's PR manager.

Jeffrey Blumberg, Ph.D, director, Antioxidants Research Laboratory, Tufts University, said green tea extract's hepatotoxicity is a complex topic. The case reports linking green tea extract to liver come from supplements that combine a variety of dietary ingredients, so it's difficult to point to green tea extract as the direct culprit.

And if it is the green tea extract that is linked to liver damage, the mechanism of action is unknown. "Although it is generally presumed that EGCG and/or other catechin flavonoids in the green tea extract are responsible for this adverse reaction, the actual harmful ingredient or ingredients are not known," Blumberg said. "While it is possible that some other ingredient in the extract is responsible for the hepatotoxicity, to date no one has been able to identify a suspect."

To further complicate the issue, Blumberg said a dose-response relationship between the amount or duration of green tea extract consumed (as reported by the patient) has not been linked to the incidence or severity of the liver damage.  "Thus, this is an idiosyncratic response with unknown biochemical, genetic, pre-existing condition, and/or other factors contributing to the hepatotoxicity."

LIVERTOX, a database of liver injuries attributable to medications and supplements, said, "The prevalence of green tea extract-induced liver injury is not known, but is probably low in comparison to the wide scale use of these products." It said  liver injury from green tea extract products usually arises within three months, and most patients recover rapidly after they discontinue use, although "fatal instances of acute liver failure have been described." 

Medline Plus, NIH's patient website, said liver problems resulting from green tea extract use are rare.

Blumberg noted, "While some rodent studies suggest high dose, life-long intake of green tea extracts can produce some toxicity (though not necessarily hepatotoxicity), randomized clinical trials (often with supradietary doses) have always shown green tea extracts to be safe."  However, he said most of these trials are brief (up to three months) and exclude other ingredients/products and are conducted in healthy people.

Supplement brand owners who wish to use the health benefits of green tea, such as energy, weight management and brain health, need to pay careful attention to potency test results to ensure the amount of green tea extract that's on the label matches the product. Also, they need to review the label and dosing guidelines with toxicologists who can ensure the product will be safe for consumers to use as described.

The New York Times article closes by implying drugs are safer because side effects are clearly stated and they have been vetted before coming to the market. However, I fail to see how products that are linked to four times the amount of liver disease cases as supplements could be safer.