Green tea drinkers: Have you seen recent claims that your favorite beverage may cause liver failure? I’m finding versions of the article everywhere. So annoying!

The headlines can be quite alarming, such as this one by the Jerusalem Post:

“Drinking green tea can have dangerous consequences—Israeli study,”

which is followed by the sobering tagline:

“Researchers from Israel’s Kaplan Medical Center discovered that drinking too much green tea can cause significant damage to the liver.”

Proclamations like this might prompt you to dump your green tea, but there’s more to the story. Although I wasn’t able to find the Israeli study article itself, a close reading of the online synopsis by the Jerusalem Post offers clues.

Historically, the claim that drinking green tea causes liver inflammation has mostly been written off; for example, the authors of one study assert that “moderate consumption of whole green tea does not cause liver injury” (Saleh et al. 2013). Cases in which someone suffered liver damage from drinking tea are few, and extenuating circumstances such as underlying health issues or medications are often involved. Isolated cases of hepatitis do show up in the literature, but there’s also a lot of research indicating that green tea components potentially inhibit hepatitis. However, some studies suggest that ingesting too much epigallocathechin 3-gallate, a green tea catechin, may cause liver damage, hence the “moderate consumption” advice.

So has this recent study found new evidence, a proven link between liver damage and drinking tea?

Per the quotes by Steven Melnick, who was part of the study, liver damage from drinking tea is “rare” and cause-and-effect is hard to prove. Their study apparently did not demonstrate that drinking tea caused the damage.

However, the online article continues, saying that “it is clear that for some people, combining green tea with other drugs and herbs can lead to severe liver disease” (Jerusalem Post 5/1/23).

Just what are these drugs and herbs? The article is pretty coy about it and it isn’t until we get to the subtitle “Other natural products that are bad for you” that we can surmise they mean green tea supplements.

Supplements—such as turmeric or ashwagandha—aren’t completely without risk, as this article points out. The same goes for green tea supplements. Note that taking supplements is not the same as drinking brewed tea because the former contain concentrated extracts of green tea.

I did find a variant of this Jerusalem Post article that clearly states that liver failure can be a consequence of drinking large amounts of green tea and taking green tea supplements (Sportskeeda 5/1/23). However, it’s unclear whether they mean drinking a lot of tea and taking supplements—or if they mean drinking lots of tea or taking supplements.

The link between green tea supplements and liver toxicity is rather old news and researchers have been delving into this connection for years. Although green tea is a natural product that has potential health benefits, supplements are a different matter. There is little regulation of these products and so we don’t always know exactly what’s in them. While they are heavily advertised as being good for us and are often marketed as nutraceuticals, few studies have been done and there’s little proof that they do anything helpful at all.

Green tea supplements are available in capsules or tablets and as ready-to-drink—and many are available. Jiang Hu et al. (2018) point out that:

A search of the U.S. Dietary Supplement Label Database using the words “green tea” as part of the dietary ingredient name produced 2373 products that contained the ingredients named green tea, green tea leaf, green tea extract (GTE), green tea powder, green tea catechins (GTC), and/or green tea phytosome.

A serving size of a green tea extract-based beverage cited by Dekant et al. (2017) has about the same amount of tea catechins as four to six cups of tea, but Hu et al. caution that every supplement has a unique dose ranging from 25 and 750 mg/serving so it’s hard to know what you’re getting. Based on their review of published studies, they conclude that it’s safe to drink brewed green tea whereas supplements, which are “based on concentrated extracts, containing high levels of individual constituents . . . and consumed in solid dosage form, may require health-based guidance values to assure their safe use” (Hu et a. 2018).

It seems that the latest study provides further evidence that green tea supplements should be taken with caution and that we should drink brewed green tea in moderation. Combining supplements with large quantities of brewed tea appears to be particularly risky. Since none of this is new information, I look forward to eventually seeing the original research to see why it sparked the dire headlines.

Meantime, I’m still drinking green tea daily. Statistically, drinking lung ching or sencha is highly unlikely to damage my liver—but such teas definitely help me relax and not be so annoyed by the abundant misleading info that I stumble across!

Sources:
–Dekant, W. et al., “Safety assessment of green tea based beverages and dried green tea extracts as nutritional supplements,” Toxicology Letters 277:104–8. 2017.
–Hu, Jiang, et al., “The safety of green tea and green tea extract consumption in adults,” Regulatory Toxicology and Pharmacology 95:412–33. 2018.
–Karamese, M. et al., “Preventive effects of a major component of green tea. . . on hepatitis-B virus DNA replication,” Asian Pacific Journal of Cancer Prevention 16. 2015.
–Saleh, I. G. et al., “Effect of green tea and its polyphenols on mouse liver,” Fitoterapia 90:151–9. 2013.
–Walla! Health, “Drinking green tea can have dangerous consequences—Israeli study,” Jerusalem Post, 5/1/23.
–Y., Soniya, “Drinking green tea can cause liver failure, new study finds,” Sportskeeda, 5/1/23.

Teas pictured are China Palace Needle, China Gunpowder Temple of Heaven, and China Lung Ching from TeaHaus, Ann Arbor.