You see green tea virtually everywhere—cakes and pastries, green tea lattes, matcha infused alcohol, just plain ol' brewed green tea, and there's a lot more than that.
But another place you'll commonly see green tea is in weight loss supplements.
There are all sorts of claims associated with its consumption, including cancer and cardiovascular disease prevention, reducing inflammation, antiarthritic, antibacterial, antiangiogenic, antioxidative, antiviral, neuroprotective, and cholesterol-lowering effects of green tea and isolated green tea extracts.
But sadly, it's not all good news where green tea extract is concerned.
What Is Green Tea Extract?
Green tea extract is exactly what it sounds like—a capsule derived from the Camellia sinensis plant that is a concentrated source of antioxidants, polyphenols, vitamins, and flavonoids naturally present in green tea.
The health benefits of green tea are largely attributed to its high content of polyphenols, especially flavanols and flavonols, which comprise about 30% of the dry weight of fresh green tea leaves 1.
But more so, these benefits of green tea and green tea extract are attributed to the most abundant catechin, (-)-epigallocatechin-3-gallate (EGCG).
Alone, EGCG isn't stable, so taking it as a sole supplement is less of an option; it becomes stable in green tea because of the presence of other antioxidants.
Benefits of GTE
If you're looking for research-backed claims for why you should take green tea extract, there's no shortage of them.
Here's a brief overview of why there's so much hype around green tea extract 2-7:
- Possesses antioxidant properties
- Protects brain function
- Promotes heart health
- Aids weight loss
- May enhance skin health
- May regulate blood glucose and insulin
Why It's Commonly Added to Fat Burning Products
If there's one area that green tea extract is particularly touted for, it's weight management and fat burning.
Tea catechins, especially EGCG, have been shown to have potent anti-obesity properties.
And while the mechanisms behind how green tea extract elicits its effects aren't yet fully understood, there's a lot of evidence suggesting it is related to specific pathways, including modulating energy balance, endocrine systems, food intake, and lipid and carbohydrate metabolism 8.
The ability of EGCG, and catechins in general, to regulate hormones that control thermogenesis labels it as an effective fat burner and weight loss aid.
What we do know green tea does is affect the function of catechol-O-methyltransferase (COMT), an enzyme that degrades catecholamines.
Research suggests that EGCG directly inhibits the activity of the COMT enzyme, which in turn increases serum concentrations of catecholamines (epinephrine and norepinephrine) and increases activity of the sympathetic nervous system.
Increased activity of the SNS plays a role in stimulating lipolysis and increasing fat oxidation 9, 10.
It is, of course, a bit more complicated than that, but it's the general idea behind how green tea extract can be beneficial for weight and fat loss.
Side Effects of GTE
While there is a pretty hefty list of positives associated with green tea extract, there's some important news that's generally not discussed that you should be aware of before you invest in some GTE.
Despite all the claims of how great it is, there have been several reports of hepatotoxicity following the consumption of green tea extract.
Liver damage is one of the biggest concerns when it comes to green tea extract that no bottles will warn you about.
And there is some research available that excessive consumption of green tea extract can be harmful for your liver—and it's not just from the caffeine.
The United States Pharmacopeia found 34 reports of liver damage, ranging from acute hepatitis to severe liver failure, following the use of various green tea extract preparations 11.
Interestingly, the hepatotoxicity that can result from green tea extract may be attributed to those same compounds that have previously been thought of as beneficial.
EGCG, specifically, is the biggest culprit 12. The major mechanisms behind hepatotoxicity include the destruction of mitochondrial membranes and the formation of reactive oxygen species.
And what's scary is this damage can happen in just three months 13. How's that for some enticements to get you to invest in a bottle?
How Much Is Safe?
When it comes to consuming green tea extract, ideally, the less the better.
There are many studies to support the general pattern that consumption of high dose green tea extract and EGCG are associated with GI toxicity and abnormal liver function biomarkers 14.
A review from 159 human studies on the effects of concentrated, catechin-rich green tea preparations resulted in hepatic adverse events in a dose-dependent manner.
Toxico- and pharmacokinetic evidence suggests that the internal dose of catechins is a key factor in any development of hepatotoxicity.
Studies recommend a safe intake level of 338 mg EGCG/day for adults in a concentrated dose (GTE) over a short period. An Observed Safe Level (OSL) of 704 mg EGCG/day may be considered for tea preparations 14.
As a general rule, if you're going to take GTE, don't exceed 500mg daily to prevent any adverse effects. But if you want to play it safe, opt for the options below.
What You Need Instead of GTE
Compounds that actually burn fat effectively can be few and far between to find, but two great ones that are proven to work are forskolin (ForsLean) and cayenne pepper extract (Capsimax).
Forskolin is a concentrated extract of the Coleus forskohlii root that acts directly on adenylate cyclase to activate cyclic adenosine monophosphate (cAMP).
cAMP is an important regulator of lipolysis and stimulates fat breakdown by upregulating thermogenesis, revving your metabolism, increasing your body's ability to use body fat, and enhancing the release of fatty acids from adipose tissue 15.
Capsimax, on the other hand, is a highly concentrated, bio-active extract from red chili peppers.
With a high concentration of capsaicinoids, Capsimax helps to support increased energy production by boosting metabolic rate, mobilizing fats for energy production, and generating heat in the body to boost internal temperature and maximize calorie burn.
When consumed, capsaicinoids elicit a response similar to that of exercise. By increasing sympathetic nervous system activity, they also upregulate secretion of catecholamines, in which serum levels play a major role in mobilizing fat stores and stimulating lipolysis.
Just 2mg per day of capsaicinoids daily is enough to increase energy expenditure by 50 kcal/day 16, which over time can add up to substantial weight loss.
If you're looking for safer alternatives to ramp up fat burn and weight loss, Burn Lab Pro is one of the cleanest, safest, and most effective fat burning supplements on the market.
It combines five powerful ingredients that work together to help you shed more fat, gain more muscle, and get the results you've always wanted.
- DL McKay, JB Blumberg. The role of tea in human health: an update. J Am Coll Nutr. 2002; 21(1): 1-13.
- JV Higdon, B Frei. Tea catechins and polyphenols: health effects, metabolism, and antioxidant functions. Crit Rev Food Sci Nutr. 2003; 43(1): 89-143.
- PV Babu, D Liu. Green tea catechins and cardiovascular health: an update. Curr Med Chem. 2008; 15(18): 1840-1850.
- S Mandel, O Weinreb, T Amit, MB Youdim. Cell signaling pathways in the neuroprotective actions of the green tea polyphenol (-)-epigallocatechin-3-gallate: implications for neurodegenerative diseases. J Neurochem. 2004; 88(6): 1555-1569.
- AG Dulloo, C Duret, D Rohrer, et al. Efficacy of a green tea extract rich in catechin polyphenols and caffeine in increasing 24-h energy expenditure and fat oxidation in humans. Am J Clin Nutr. 1999; 70(6): 1040-1045.
- PH Lu, CH Hsu. Does supplementation with green tea extract improve acne in post-adolescent women? A randomized, double-blind, and placebo-controlled clinical trial. Complement Ther Med. 2016; 25: 159-163.
- RA Anderson, MM Polansky. Tea enhances insulin activity. J Agric Food Chem. 2002; 50(24): 7182-7186.
- SM Chacko, PT Thambi, R Kuttan, I Nishigaki. Beneficial effects of green tea: a literature review. Chin Med. 2010; 5: 13.
- RT Borchardt, JA Huber. Catechol O-methyltransferase. 5. Structure-activity relationships for inhibition by flavonoids. J Med Chem. 1975; 18(1): 120-122.
- DS Goldstein, G Eisenhofer, IJ Kopin. Sources and significance of plasma levels of catechols and their metabolites in humans. J Pharmacol Exp Ther. 2003; 305(3): 800-811.
- DN Sarma, ML Barrett, ML Chavez, et al. Safety of green tea extracts: a systematic review by the US Pharmacopeia. Drug Saf. 2008; 31(6): 469-484.
- G Galati, A Lin, AM Sultan, PJ O'Brien. Cellular and in vivo hepatotoxicity caused by green tea phenolic acids and catechins. Free Radic Biol Med. 2006; 40(4): 570-580.
- United States National Library of Medicine. Drug Record Green Tea (Camellia sinesis) Available from: http://livertox.nlm.nih.gov/GreenTea.htm. Accessed October 15, 2012.
- J Hu, D Webster, J Cao, A Shao. The safety of green tea and green tea extract consumption in adults - Results of a systematic review. Regul Toxicol Pharmacol. 2018; 95: 412-433.
- S Henderson, B Magu, C Rasmussen, et al. Effects of coleus forskohlii supplementation on body composition and hematological profiles in mildly overweight women. J Int Soc Sports Nutr. 2005; 2(2): 54-62.
- J Deshpande, S Jeyakodi, V Juturu. Tolerability of Capsaicinoids from Capsicum Extract in a Beadlet Form: A Pilot Study. J Toxicol. 2016; 2016: 6584649.