As high doses of green tea extract supplements for weight loss become more popular, potential liver toxicity becomes a concern.
In the last decade, dozens of people have been diagnosed with the condition.
However, drinking green tea in the weeks before taking supplements likely reduces risk, according to researchers in Penn State’s College of Agricultural Sciences.
Researchers gave mice high doses of the green tea polyphenol epigallocatechin-3-gallate (EGCG). The dosage was equivalent to the amount of the polyphenol found in some dietary supplements taken by humans.
One group of mice was pretreated with a diet containing a low level of ECGC for two weeks prior to receiving high doses of the polyphenol.
Another group was fed a diet that did not include EGCG prior to receiving the high, supplement-like doses.
After three days of high doses, the scientists tested the blood of the mice to determine how their livers handled the EGCG. Pretreated mice had a 75 percent reduction in liver toxicity compared to untreated mice.
The research data show that dietary pretreatment with the green tea polyphenol protects mice from liver toxicity caused by subsequent high oral doses of the same compound, explained Josh Lambert, associate professor of food science.
He suggested that the research has relevance to people who are taking or are considering taking supplements containing green tea extract.
“We believe this study indicates that those who are chronic green tea consumers would be less sensitive to potential liver toxicity from green-tea-based dietary supplements,” he said.
“If you are going to take green tea supplements, drinking green tea for several weeks or months ahead of time may reduce your potential side effects.”
Lambert has another suggestion for people considering green tea supplements — drink green tea instead.
“Drinking green tea rather than taking supplements will allow you to realize the benefits and avoid the risk of liver toxicity,” he said.
“The beneficial effects that people have reported as being associated with green tea are the result of dietary consumption rather than the use of supplements. The relative risk of using supplements remains unclear.”
Citation: James KD, et al. (2015). Dietary pretreatment with green tea polyphenol, (−)-epigallocatechin-3-gallate reduces the bioavailability and hepatotoxicity of subsequent oral bolus doses of (−)-epigallocatechin-3-gallate. Food and Chemical Toxicology, 76: 103. DOI: 10.1016/j.fct.2014.12.009.
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