What Researchers Say About Green Tea and Metabolism
Green tea has a healthy reputation. Here is what federal health researchers actually say about its effects, and the safety questions worth knowing.
Green tea shows up everywhere in health conversations, from weight loss to heart health. It has been part of daily life in parts of Asia for centuries, and it is rich in plant compounds called catechins.
So what does the research actually support? The National Center for Complementary and Integrative Health (NCCIH), part of the U.S. National Institutes of Health, summarizes the evidence in plain language.
What the evidence suggests
According to the NCCIH, the catechins and caffeine in green tea and its extracts may have a modest effect on body weight. "Modest" is the key word. Green tea is not a shortcut, but it can be part of an overall healthy pattern of eating.
A cup of tea vs. a capsule
Most of the safety questions involve concentrated green tea extracts, not the tea you brew in a mug. The NCCIH notes that no safety concerns have been reported for green tea consumed as a beverage by adults, although it does contain caffeine.
Extracts are different. The NCCIH reports that, although uncommon, liver injury has been reported in some people who used green tea products, mainly extracts in tablet or capsule form.
Possible medication interactions
Green tea can interact with some medications. The NCCIH lists examples including:
- Nadolol, a beta-blocker used for high blood pressure and heart problems. High doses of green tea have been shown to reduce its levels in the blood.
- Atorvastatin, a cholesterol-lowering drug. Green tea extract can reduce its blood levels.
- Raloxifene, used to treat osteoporosis. A study found an interaction with green tea.
The bottom line
Enjoying green tea as a beverage is generally considered safe for adults. If you are thinking about green tea extract supplements, or you take any of the medications above, talk to your doctor or pharmacist first.