LIKE MANY THINGS from the 90s—bucket hats, cargo pants, Tupac T-shirts—green tea extract is currently back in fashion. At least if you look on social media, where some influencers claim that the supplement can help you burn fat and feel great doing it.
Supplement companies that make green tea extract promote weight-loss claims, but also that their pills, powders, and potions will support your metabolism, help you maintain normal cholesterol, and blood flow, and more.
“Green tea supplements are marketed as the panacea for a number of different psychological, metabolic and cardiac health issues,” says Nenad Naumovski, PhD, Professor in Food Science and Human Nutrition at the University of Canberra in Australia. “However, the evidence behind these claims is still relatively limited.”
What Is Green Tea Extract?
IT’S A CONCENTRATED form of ingredients found in green tea leaves.
Decades of scientific research suggest that people who regularly drink green tea are healthier than those who don’t.
That’s due to potent green tea antioxidants called catechins, especially epigallocatechin-3 Gallate (EGCG), are the star ingredients. “They help to lower oxidative stress, specifically LDL oxidation, which helps with preventing the progression of heart disease,” says Michelle Routhenstein, MS, RD, a preventive cardiology dietitian and heart health expert at Entirely Nourished.
Swallowing a green tea pill, however, is not like sipping a cupful. Green tea supplements are concentrated with high amounts of antioxidants that would be nearly impossible to reach by drinking normal amounts of tea, says Naumovski.
Some product labels list the EGCG amount per capsule, others list total polyphenols—EGCG and its catechin cousins, and some also list L-theanine, a green tea amino acid linked to brain benefits.
Will all these compounds help you? Maybe, maybe not. “The strongest evidence for potential beneficial health effects is found in the management of psychological stress and improvements in mood,” says Naumovski. “However, the studies in this area still remain relatively scarce.”
An antioxidant megadose can also backfire. “The levels of the phytochemicals found in the products can induce several negative health effects,” he says. Green tea extract has been linked to liver problems, including liver failure, in some users.
What Is Green Tea Extract Good For?
WELL, SCIENCE HAS shown some benefits in some areas.
Green tea extract might reduce cholesterol and blood sugar.
A study review published in Frontiers in Nutrition found that green tea supplements reduced artery-clogging triglycerides by about 8 milligrams per deciliter (mg/dL), LDL cholesterol by about 6 mg/dL, fasting blood sugar by about 2 mg/dL, and HbA1c by about 0.15 percent. Green tea extract might reduce intestinal absorption of cholesterol and raise blood levels of adiponectin, a hormone that helps regulate blood sugar.
Green tea supplements could boost your workouts.
A study review in Nutrition Research suggests that taking green tea extract before exercise for a week or more might help protect your cells against exercise-induced oxidative stress that could otherwise impair performance.
Is Green Tea Extra Good for Weight Loss?
IT’S NOT EXACTLY a weight-loss miracle.
Green tea extract supplements were linked with an average weight loss of 1.4 pounds in a study review published in the British Journal of Nutrition. Their catechins might help reduce absorption of fats and protein in your gastrointestinal tract. But 1.4 pounds? You can do other things to safely lose that and more.
“When we focus in on a diet that has the nutrients that help with allowing for satiety, allowing for good metabolic function and leading to a caloric deficit, we get better weight loss and more consistent weight loss results,” says Routhenstein.
Optimizing your diet also helps your heart. “Adding in more soluble and insoluble fiber and addressing gut health can help with reducing cholesterol in the gut, which will help lower our LDL values a lot more than a than a green tea extract, or really, any supplement for that matter,” she says.
Should You Take Green Tea Extract?
ROUTHENSTEIN RECOMMENDS SKIPPING green tea extract. Drink up to four cups of green tea per day instead. She likes Sencha by Rishi Tea and Botanicals.
If you really want your tea in supplement form, talk to your doctor first, especially if you have diabetes, heart-health issues, or are overweight or over age 50, says Naumovski. Review your health history and medications. Green tea extract can make some drugs less effective. It can also increase your risk of side effects.
“If you’re on a blood thinner, a statin, or certain antibiotics, and you take a green tea extract, especially a high-dose green tea extract, you’re putting more pressure on your liver, and you’re adding in potential harm from a drug-supplement interaction that doesn’t happen in the lower dosages found in actual green tea consumed in the right amounts,” says Routhenstein.
A safety review by the U.S. Pharmacopeial Convention advises avoiding green tea supplements if you have a liver problem.
If you try green tea supplements anyway:
Watch your liver.
Tell your doctor if you develop signs of trouble: abdominal pain, dark pee, or yellowing skin or eyes. Help your liver by taking these supplements with food, not on an empty stomach. The European Food Safety Authority says it’s risky to take 800 mg of green tea extract or more. Some people have developed liver problems using even less.
Consider paring down your supplement regimen.
“Another strategy is to reduce the number of supplements being consumed at the same time, especially ones that are marketed to have high polyphenolic and antioxidant content,” says Naumovski. “It is important to remember that too much of the good thing can be harmful, particularly if you don’t need it.”
Check for caffeine.
Some green tea supplements have no caffeine. Others have more than a cup of coffee. Don’t combine them with caffeinated pre-workout supplements, says Naumovski. Excess caffeine can cause anxiety, tremors, irritability, headache, and sleeping problems.
Stay in touch with your doctor.
If you take certain medications, you might need extra lab work when using green tea extract.