Many green tea supplements on the market claim to help with weight loss or a healthier metabolism, but health experts at Consumer Reports warn the products could actually be dangerous and recommend you avoid them altogether.

“Higher concentrations of green tea extract can potentially cause serious liver damage. Plus the herb itself has been found to alter the effectiveness of a long list of drugs, including certain antidepressants and anti-clotting medications,” said Jeneen Interlandi, Consumer Reports.

It can also elevate your heart rate and blood pressure. And researchers suggest that up to 10 per cent of people who suffer acute liver failure from green tea extract may die as a result.

That's why Consumer Reports put green tea extract powder on its list of 15 supplement ingredients to avoid.

“The manufacturers who make these supplements are not required to prove to federal regulators that their products are safe, that they’re effective or even that they are accurately labelled, so you really don’t know what you’re buying,” explained Interlandi.

In Canada, the labels of all licensed natural health products containing green tea extract are required to includ a warning to consumers to "Consult a health care practitioner prior to the use if [they] have a liver disorder or develop symptoms of liver trouble."

Studies have also found that even in high doses green tea probably won’t help you lose weight.

“It’s true that green tea can raise your metabolic rate, so you burn more calories, but that’s probably just due to its caffeine and catechins it contains. Catechins are antioxidants that are found in green tea,” said Interlandi.

Instead, reap the health benefits of green tea by enjoying a couple of cups a day.

Matcha powder also has a much lower concentration of catechins than green tea supplements. A cup of matcha contains about 50 mg of catechins, whereas supplements can range from 250 to 750 mg of catechins.

Other supplement ingredients on Consumer Reports list to avoid include kava, caffeine powder and red yeast rice. For the full list click here.