Hepatotoxicity of green tea: an update

Abstract

Green tea (GT), obtained from the leaves of Camellia sinensis (L.) Kuntze (Fam. Theaceae), is largely used for its potential health benefits such as reduction in risk of cardiovascular diseases and weight loss. Nevertheless, it is suspected to induce liver damage. Present work reviews the hepatic adverse reactions associated with GT-based herbal supplements, published by the end of 2008 to March 2015. A systematic research was carried out on PubMed, MedlinePlus, Scopus and Google Scholar databases, without any language restriction. Moreover, some accessible databases on pharmacovigilance or phytovigilance were consulted. The causality assessment was performed using the CIOMS/RUCAM score. Nineteen cases of hepatotoxicity related to the consumption of herbal products containing GT were identified. The hepatic reactions involved mostly women (16/19); the kind of liver damage was generally classified as hepatocellular (16/19). The causality assessment between consumption of herbal preparation and hepatic reaction resulted as probable in eight cases and as possible in eleven cases. In seven cases, patients used preparations containing only GT, while twelve reactions involved patients who took multicomponent preparations (MC). The reactions induced by GT had a generally long latency (179.1 ± 58.95 days), and the outcome was always resolution, with recovery time of 64.6 ± 17.78 days. On the contrary, liver injury associated with MC had a shorter latency (44.7 ± 13.85 days) and was more serious in four cases that required liver transplantation and, when resolution occurred, the recovery time was longer (118.9 ± 38.79). MC preparations contained numerous other components, many of which are suspected to induce liver damage, so it is difficult to ascribe the toxicity to one specific component, e.g., GT. Present data confirm a certain safety concern with GT, even if the number of hepatic reactions reported is low considering the great extent of use of this supplement. The mechanism of GT hepatotoxicity remains unclear, but factors related to the patient are becoming predominant. A major safety concern exists when GT is associated with other ingredients that can interact between them and with GT, enhancing the risk of liver damage. Patients should be discouraged from using herbal or dietary supplements containing complex mixtures and should be encouraged to use herbal and dietary supplement possibly under supervision of healthcare professionals.

Epigallocatechin-3-gallate enhances key enzymatic activities of hepatic thioredoxin and glutathione systems in selenium-optimal mice but activates hepatic Nrf2 responses in selenium-deficient mice

“…2A), thus the dose of EGCG employed in this study, although much higher than that resulted from consumption of tea beverages, is similar to the consumption of green tea extract-based dietary supplements (for weight loss), in which EGCG is a major ingredient. Adverse reactions, mainly hepatotoxicity, owing to copious consumption of green tea extracts by some individuals have been observed, but the percentage is rather low [73], [74]. It is likely that presently observed responses of anti-oxidative defense systems serve as the protective mechanisms.…”

Green Tea and Its Extracts in Cancer Prevention and Treatment

“…Drinking green (or black) tea in itself likely does not carry a risk [37] since the amount of absorbed catechins remains low at or below 1 µmol/L [269]; herbal extracts including green tea extracts with much higher amounts of catechins and flavones can cause hepatotoxicity [268,[270][271][272]. This compares to other plant extracts which are toxic in larger amounts if taken as tea (or in other preparations) [13,271,273], or in excessive doses as has been shown for caffeine [274,275].…”

A Case of Serial Liver Injury Induced by Plant Food Supplements in a Young Healthy Man

“…Hepatotoxicity of green tea preparations, mainly containing unusual concentration of catechins, has been reviewed [7,13]. Although the bioavailability of catechins is low after oral administration, plasma levels can reach toxic levels under fasting or repeated administration.…”

“…In recent years, several reports have highlighted the beneficial effects of botanicals or PFS in the prevention of some chronic diseases [1,2]. But these positive effects are accompanied by the increased incidence of hepatic damage caused by herbal medicines, including PFS [3][4][5][6][7]. We are presenting two repeated cases of acute hepatitis occurred in the same patient for two consecutive years, after taking the same PFS.…”