The scientific opinion from the EU science agency provides a safety assessment of green tea catechins after concerns were passed on regarding possible harmful effects on the liver in Nordic countries.
In 2016, the Norwegian food safety authority Mattilsynet warned against green tea extract supplements following reports of liver damage. The authority pointed to high levels of the active substance EGCG (epigallocatechin-3-gallate) in the products, which were far above that obtained from just drinking green tea.
Now EFSA’s ANS Panel has provided a scientific opinion on the safety of green tea catechins from dietary sources, including preparations such as food supplements and infusions. In its report, the panel concludes that while intake of green tea catechins from green tea infusions are generally safe, there is potential for liver damage from supplementation with doses of EGCG above at 800 mg per day.
What are catechins?
- Catechins are a group of compounds found in tea, fruit, chocolate and wine.
- They belong to a group of phytonutrients called flavonoids, and have been linked to a variety of health benefits.
- Epigallocatechin gallate (EGCG) is the main catechin present in green tea.
- EGCG has been linked to a variety of health benefits at lower levels, but a risk of liver damage at higher doses.
- EFSA said it was unable to determine a ‘safe level’ for catechins in supplements, but noted that green tea products – and in particular supplements – should include the content of catechines and the proportion of EGCG on labels.
“The Panel recommended that studies should be performed to determine a dose–response of hepatotoxicity of green tea catechins and examine inter and intra species variability,” the scientific opinion states.
“Maximum limits for pyrrolizidine alkaloids in green tea preparations, including food supplements should be established, since they may contribute to hepatotoxicity.”
EFSA’s advice will now be put forward to the European Commission, which will decide on the most appropriate risk management follow-ups.
History of risk
In addition to previous warnings on safety from Norwegian authorities, there have been several reports of countries issuing warnings or investigating the safety of green tea supplements after links to safety issues.
Papers published in the Annals of Internal Medicine and the European Journal of Clinical Pharmacology linked dozens of cases of liver damage to green tea EGCG.
Health Canada recently warned against green tea pills following a federal safety review – prompted after a teenager took the pills and needed dialysis for her liver. Meanwhile, other reports have indicated cases involving a man in Australia who required a liver transplant and a 16-year-old girl in England who was rushed to hospital with a form of hepatitis after taking green tea slimming pills.
At the time of the initial Norwegian warning Dr Luca Bucchini, managing director of Italian firm Hylobates Consulting, told NutraIngredients that the issue was a "well known problem which has never been really tackled".
Daily intake risk?
According to the new EFSA safety opinion, doses of EGCG at 800 mg/day may be associated with initial signs of liver damage.
“While there was no indication of liver injury for doses below 800 mg/day from green tea supplements, experts were unable to identify a safe dose based on available data,” the EFSA panel said.
According to the opinion, the average daily intake of EGCG resulting from the consumption of green tea infusions ranges from 90 to 300 mg/day – with ‘high-level consumers’ likely to have an intake of up to 866 mg/day.
Meanwhile, food supplements containing green tea catechins were found to provide a daily dose of EGCG in the range of 5–1,000 mg/day, for adult population, it said.
The report also cited data from a 2013 study, which analysed the content of catechins in 97 dietary supplements, obtained from subjects in the drug‐induced liver injury network (DILIN).
In that study 50% of products contained at least one catechin, but the presence of catechins was not indicated on the label in 40% of all cases.
According to that same data, the concentration and composition of catechins varied widely. In supplements that declared catechins on the label, the team reported concentrations ranging from non‐detectable to 486 mg/g. Meanwhile in supplements not labelled with green tea or catechins concentration were much lower and varied from 3 μg/g to 6 mg/g.