Cassia Cinnamon and Green Tea Extract: Liver Safety Explained

Injury is uncommon but real, and it is mainly reported with extracts in capsule form.

NIH LiverTox rates green tea extract a well-established cause of clinically apparent liver injury, usually an acute hepatitis-like pattern 1 to 6 months after starting. Most people recover on stopping, but fatal liver failure has occurred, and there is no clear dose dependency (NIH LiverTox, Green Tea). NCCIH says there are no safety concerns for green tea as a beverage in adults, and that an immune-gene variant carried by 5 to 15 percent of Americans may raise susceptibility (NCCIH, Green Tea).

A USP review links case reports to EGCG intakes from 140 mg to about 1,000 mg a day with wide differences between people, and notes that bolus doses on an empty stomach raise EGCG absorption (USP 2020, green tea extract review). The CogniHoney percentage "(50%)" is printed without saying what it refers to, and no amount is printed, so none of these figures can be matched to a capsule.

Cassia contains coumarin.

NCCIH says interactions between coumarin and the liver have been reported, and that prolonged use of cassia could be an issue for sensitive people such as those with liver disease. Ceylon cinnamon has only trace coumarin, and product labels often do not name the species (NCCIH, Cinnamon). The CogniHoney list says only "cinnamon extract", so we do not know which is in the capsule.

A review derived a tolerable daily intake for coumarin of 0.1 mg per kg of body weight, and found that heavy cassia consumers can reach it (Abraham 2010, coumarin risk). As arithmetic only: for a person weighing 70 kg, that is 7 mg a day. How much coumarin a capsule adds depends on species and amount, neither of which we can see. If the species and the amount were both printed, the sum would take a minute; without them, the honest answer is that nobody outside the manufacturer can say.

You cannot tell from the outside, which is why a liver history and a conversation matter.

NCCIH says an immune-gene variant carried by 5 to 15 percent of Americans may raise susceptibility to liver injury from green tea extract (NCCIH, Green Tea). Most carriers will never know. USP also notes wide differences in susceptibility between people at the same intake (USP 2020, green tea extract review). So a dose that one person takes without trouble is not a safe level for another, and a published range cannot be treated as a personal limit.

Ask your doctor whether your history of liver disease, heavy alcohol use or medicines that tax the liver makes either line a poor fit. Liver tests are the doctor's call, and asking about them is reasonable. This site cannot say whether you need them.

• Which cinnamon species is it, cassia or Ceylon?
• How much green tea extract is in a capsule, and does it contain caffeine?
• Should I have liver tests before and during use?
• Do I take atorvastatin or nadolol?
• Does my liver history make either line a poor idea?

Print this list or save it to your phone. The green tea extract profile and cinnamon extract profile give the research behind each question.