Trending Topics pieces (Article Analyses, Evidence Clips and Other Topics) are published in timely response to recent media and journal articles, position statements, clinical guidelines, etc. Since they are based on the most recent evidence/publications, they may not be consistent with PEN evidence in other PEN content areas. As soon as possible, when this occurs, the PEN content will be reviewed and updated as needed.
Green Tea Extract Supplements
On February 3, 2017, the Canadian Broadcast Corporation (CBC) Marketplace program described some cases of serious harm associated with green tea extract supplements that included hepatotoxicity, liver transplants and even death. In their feature story they point out that labelling a product as 'natural' does not assure that it works or that it is safe.
Since 2011, the evidence synthesis on green tea extract within the PEN® System is that any potential weight loss effect of green tea extract supplements is small and of questionable clinical significance and supplements are associated with the risk of hepatotoxicity and other side-effects. The practice question on this topic is currently being reviewed. Studies identified thus far also did not report clinically meaningful differences in weight loss between green tea extract and placebo. Of importance, more papers were published highlighting the potential for rare but serious risks of hepatotoxicity and severe liver damage from supplementation and weight loss products containing green tea (single and multi-ingredient products). Specifically, three publications (see below) describing 18 cases of hepatotoxicity, which resulted in liver transplantation for six individuals were identified and are being reviewed for incorporation into the PEN analysis on this topic.
See Additional Content:
Are green tea supplements safe and effective for weight loss among overweight or obese adults?
Health Canada case report describing the 17-year-old profiled in the CBC Marketplace program.
Mazzanti G, Di Sotto A, Vitalone A. Hepatoxicity of green tea: an update. Arch Toxicol. 2015 Aug;89(8):1175-91. doi: 10.1007/s00204-015-15121-x. Epub 2015 May. Abstract available from: https://www.ncbi.nlm.nih.gov/pubmed/25975988
Zheng EX, Rossi S, Fontana RJ, Vuppalanchi R, Hoofnagle JH, Kham I, et el. Risk of liver injury associated with green tea extract in SLIMQUICK(®) weight loss products: results from the DILIN prospective study. Drug Saf. 2016 Aug;39(8):749-54. doi: 10.1007/s40264-016-0428-7. Abstract available from: https://www.ncbi.nlm.nih.gov/pubmed/27189593
Whitsett M, Marzio DH, Rossi S. SlimQuick™ - associated hepatoxicity resulting in fulminant liver failure and orthotopic liver transplantation. ACG Case Rep J. 2014 Jul;1(4):220-2. doi: 10.14309/crj.2014.59. eCollection 2014. Abstract available from: https://www.ncbi.nlm.nih.gov/pubmed/26157882
Kombucha Tea - Some Pros and Cons
Kombucha tea is a fermented drink made with sugar, tea, yeast and bacteria (1,2). It has been widely consumed around the world and there has been an increasing interest in drinking kombucha tea due to it being a probiotic beverage and its claimed potential health benefits. It is available commercially but is often prepared at home by combining the kombucha culture with sugared tea and allowing it to ferment. The composition of kombucha tea can vary depending on the starter tea, yeasts and bacteria contained in the culture, and the fermentation process.
A review in Comprehensive Reviews in Food Science and Food Safety provides an overview of the microbiology, composition, fermentation and potential benefits found in the literature up to 2013 (1). The authors noted that the biological effects underpinning the many health claims specific to kombucha consumption; notably antimicrobial, antioxidant, hepatoprotective and anticancer properties; have only been studied in animal and cell cultures. The authors concluded that kombucha tea can be part of a healthy diet, but more research is needed to determine its biological effects on humans.
There are some safety issues, mostly associated with non-commercially prepared kombucha. According to the Natural Medicines Comprehensive Database, kombucha tea when made in unhygienic conditions has been implicated in some cases of transmitted opportunistic pathogens and Aspergillus mould (2). Kombucha tea is contraindicated for pregnant and lactating women, and may be unsafe for people who are immune compromised.
Given the interest in the effect of the microbiome on health, and the effect of fermented foods (yogurt, miso, tempeh, kimchi, etc.) on the microbiome, more human studies involving kombucha tea are anticipated. Watch for an upcoming PEN® Practice Question on kombucha tea.
- Jayabalan R, Malbaša RV, Lončar ES, Vitas JS, Sathishkumar MA. Review on kombucha tea – microbiology, composition, fermentation, beneficial effects, toxicity, and tea fungus. Comprehensive Reviews in Food Science and Food Safety. 2014 July;13(4). Available from: http://onlinelibrary.wiley.com/doi/10.1111/1541-4337.12073/full
- Therapeutic Research Faculty. Natural
Medicines Comprehensive Database. [cited 2016 Nov 11]. Available
Revised November 17, 2016