Green tea extract is one of four ingredients in GlucoZone. This article is for general education only and is not medical advice.
What is green tea extract?
Green tea comes from the leaves of Camellia sinensis – the same plant used to make black and oolong tea. The difference is in the processing: green tea leaves are steamed or pan-fired and dried without being fermented, which helps preserve their natural plant compounds. Green tea has been part of daily life in China and across Asia for thousands of years.
Green tea extract is a concentrated form of the leaf. Its best-known compounds are catechins – especially one called EGCG (epigallocatechin gallate) – which are antioxidants. Green tea also naturally contains some caffeine.
From tea leaf to green tea extract
Green, black and oolong tea all come from the same plant: Camellia sinensis
1
Fresh leaves
Camellia sinensis
2
Steamed or pan-fired
gently heated
3
Dried
not fermented
4
Green tea extract
concentrated leaf compounds
Key natural compounds: catechins (antioxidants), especially EGCG • natural caffeine
Black tea, by contrast, is fermented (oxidized) before drying.
What are researchers studying?
Green tea is one of the most widely studied plants in nutrition research. According to the National Institutes of Health's National Center for Complementary and Integrative Health (NCCIH), studies have looked at heart health, cholesterol and body weight. NCCIH reports that green tea reduced total and LDL cholesterol to a small extent in studies, and that its catechins and caffeine may have a modest effect on body weight. Memorial Sloan Kettering Cancer Center's herb database notes that green tea is widely used to support heart health.*
NCCIH also notes that results are often inconsistent and that many questions remain, so it's best to think of green tea as one supportive part of a healthy routine rather than a quick fix.
How green tea extract fits into GlucoZone
GlucoZone combines green tea extract with berberine HCl, turmeric root extract and black pepper extract in one liquid dropper a day – designed to support healthy glucose metabolism and antioxidant protection as part of a healthy diet and active lifestyle.*
Important safety information
- Liver health. Liver injury is rare but has been reported with concentrated green tea extracts, usually at high doses. Health experts, including the U.S. Pharmacopeia, advise people with liver problems not to use green tea extract, and to stop use and contact a doctor if they notice unusual tiredness, nausea, stomach pain, dark urine or yellowing of the skin or eyes. The NIH's LiverTox database suggests taking green tea extract with meals.
- Taking medication? Green tea can reduce the effect of some medicines, including the blood-pressure drug nadolol, certain cholesterol-lowering statins and some cancer drugs. Check with your doctor or pharmacist first.
- Pregnant or nursing? Do not use GlucoZone if you are pregnant or nursing.
- Caffeine. Green tea extract contains caffeine. If you are sensitive to caffeine, keep this in mind with coffee, tea and other sources.
- Possible side effects can include nausea, stomach upset, constipation or trouble sleeping.
GlucoZone™
Berberine HCl, turmeric root extract, green tea extract and black pepper extract in one easy liquid dropper a day.*
Sources & further reading
- National Center for Complementary and Integrative Health (NIH). Green Tea: Usefulness and Safety. Updated February 2025.
- Memorial Sloan Kettering Cancer Center. About Herbs: Green Tea.
- National Institute of Diabetes and Digestive and Kidney Diseases (NIH). LiverTox: Green Tea.
- Sarma DN, et al. Safety of green tea extracts: a systematic review by the US Pharmacopeia. Drug Safety. 2008.
*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. The information in this article is for educational purposes and is not a substitute for advice from your healthcare provider.