Get Your Personalized Supplement StackSupplement Stack Quiz

Green And Black Tea Extract

Also known as: Green tea extract (GTE), Black tea extract (BTE), Tea polyphenols, EGCG, Theaflavins, Camellia sinensis Extract

Overview

Green and black tea extracts are concentrated forms of bioactive compounds derived from the leaves of Camellia sinensis. Green tea extract is rich in catechins, particularly epigallocatechin gallate (EGCG), due to its unfermented processing. Black tea extract, conversely, contains theaflavins and thearubigins, which are formed during the fermentation process. These extracts are primarily utilized for their potential benefits in cardiovascular health, metabolic regulation (including glucose and lipid metabolism), and their potent antioxidant properties. They are classified as botanical extracts and polyphenol-rich dietary supplements, with a moderate to high level of research maturity, supported by numerous randomized controlled trials and meta-analyses.

Benefits

Green and black tea extracts offer several evidence-based benefits, particularly for cardiovascular and metabolic health. Green tea extract has been shown to reduce systolic blood pressure (SBP) by approximately 1.98 mmHg and has a modest effect on diastolic blood pressure (DBP). It also significantly reduces fasting blood glucose, though it does not consistently impact fasting insulin or HbA1c. Black tea extract can reduce SBP by about 1.85 mmHg and significantly lowers LDL cholesterol by approximately 0.43 mmol/L, a clinically relevant reduction for cardiovascular risk. While some evidence suggests anti-inflammatory effects, particularly through modulation of C-reactive protein (CRP), findings are inconsistent. Benefits are most observed in adults with cardiovascular risk factors like hypertension and dyslipidemia, and in those with impaired glucose metabolism. The modest blood pressure reductions are considered meaningful at a population level for cardiovascular risk reduction. Effects can be observed within weeks, with lipid improvements potentially requiring longer supplementation durations (up to 6 months).

How it works

The primary mechanisms of action for green and black tea extracts involve their rich polyphenol content, specifically catechins (EGCG) and theaflavins. These compounds act as potent antioxidants, scavenging free radicals and reducing oxidative stress throughout the body. They also modulate endothelial nitric oxide synthase (eNOS), leading to increased nitric oxide (NO) production, which improves vasodilation and contributes to blood pressure reduction. Furthermore, these extracts may inhibit the nuclear factor kappa B (NF-κB) pathway, thereby reducing inflammation. In the cardiovascular system, they improve endothelial function and reduce LDL oxidation. Metabolically, they influence glucose metabolism by potentially improving insulin sensitivity and reducing glucose absorption. While catechins have moderate bioavailability, their bioefficacy can be influenced by formulation and co-ingestion with other nutrients, with black tea polyphenols having distinct metabolites.

Side effects

Green and black tea extracts are generally considered safe when consumed within recommended supplemental doses. Common side effects, though infrequent, include mild gastrointestinal discomfort. Uncommon side effects (1-5% incidence) may involve rare allergic reactions or caffeine-related symptoms such as jitteriness, depending on the extract's caffeine content. Very rarely (less than 1%), hepatotoxicity has been reported, primarily with high-dose green tea extracts in isolated cases, and is not typical with standard dosages. Potential drug interactions include anticoagulants (due to trace vitamin K in tea), stimulant medications, and certain cardiovascular drugs. Caution is advised for pregnant or breastfeeding individuals and those with pre-existing liver disease, who should consult a healthcare professional before use. Data on children and the elderly are limited, and individuals sensitive to caffeine should exercise caution.

Dosage

For green tea extract, a minimum effective dose of around 300 mg of catechins per day has shown effects on blood pressure and glucose. Optimal dosage ranges typically fall between 300–600 mg of catechins per day. Black tea extract dosages vary but are often standardized to polyphenol content equivalent to consuming 3–5 cups of brewed tea daily. The maximum safe dose for green tea catechins is generally considered up to 800 mg per day; however, higher doses warrant caution due to rare reports of liver toxicity. To improve tolerance and absorption, it is often recommended to take divided doses with meals. For consistency, extracts standardized to EGCG (for green tea) or theaflavins (for black tea) are preferred. While no specific cofactors are strictly required, co-administration with vitamin C may enhance catechin bioavailability.

FAQs

Is green and black tea extract safe for daily use?

Yes, generally safe at recommended doses with minimal side effects for most individuals.

Can these extracts replace medication for hypertension or diabetes?

No, they are supportive supplements and should not replace prescribed medical treatments for chronic conditions.

How soon can benefits be expected?

Some effects on blood pressure and glucose may appear within weeks, while lipid changes might require longer supplementation periods.

Are caffeine effects a concern?

Extracts vary in caffeine content; decaffeinated options are available for individuals sensitive to caffeine.

Does brewing tea provide the same benefits as extracts?

Extracts provide standardized and higher concentrations of active compounds compared to typical brewed tea.

Research Sources

https://pmc.ncbi.nlm.nih.gov/articles/PMC7350188/ – This systematic review and meta-analysis of RCTs found that green tea supplementation significantly reduces fasting blood glucose, but had no significant effect on fasting insulin or HbA1c. The study highlights heterogeneity in doses and populations among the included trials, yet provides a high-quality assessment of green tea's impact on glycemic control.
https://pmc.ncbi.nlm.nih.gov/articles/PMC7433290/ – This Cochrane Review, based on 11 RCTs, concluded that black tea reduces LDL cholesterol and systolic blood pressure significantly. While it noted some risk of bias and a small number of trials per outcome, it provides moderate-quality evidence for black tea's cardiovascular benefits over durations up to 6 months.
https://www.nature.com/articles/srep06251 – This meta-analysis of 13 RCTs demonstrated that green tea significantly reduces systolic blood pressure by approximately 1.98 mmHg, with modest effects on diastolic blood pressure. Despite including some lower-quality studies and noting heterogeneity, the study followed PRISMA guidelines, providing moderate-quality evidence for green tea's antihypertensive effects.
https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2022.1084455/full – This systematic review and meta-analysis indicated that green tea supplementation improves lipid profiles, though effects on C-reactive protein (CRP) were inconsistent. The study, which applied GRADE assessment, noted statistical heterogeneity and potential publication bias, but overall provides moderate to high-quality evidence for green tea's impact on lipids.
https://journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0103247 – This systematic review and meta-analysis of 11 RCTs found that black tea reduces systolic blood pressure by 2 mmHg and diastolic blood pressure by 1 mmHg. Despite the modest effect size and relatively small sample size across studies, it provides moderate-quality evidence supporting black tea's role in blood pressure regulation.