The Health Benefits of Green Tea

Fresh green tea

The main bioactive components in green tea are polyphenols known as catechins, especially epigallocatechin gallate (EGCG), epigallocatechin (EGC), epicatechin gallate (ECG) and epicatechin (EC). EGCG makes up 59% of the catechins in green tea.

Green tea

Studies demonstrate that the body absorbs and circulates green tea catechins systemically after oral ingestion. Catechin byproducts can be found in the blood and urine, reaching highest levels at 1-2 hours and 4-6 hours. Catechin bioavailability is dose dependent.

Extensive research demonstrates that green tea has diverse health benefits:

Anticancer Properties:

  • EGCG exhibits anti-angiogenic, anti-proliferative, pro-apoptotic and anti-metastatic mechanisms in various cancers like breast, prostate, lung and colorectal.
  • Human studies suggest green tea protects against certain cancers, especially with habitual long-term consumption. Case-control studies show the most consistent results.
  • Green tea or catechin mixtures may be more effective than isolated EGCG supplementation.

Cardiovascular Health:

  • Population studies link green tea intake to reduced cardiovascular mortality. It improves endothelial function, blood pressure, cholesterol, and biomarkers of inflammation and oxidative stress.
  • Green tea catechins inhibit platelet aggregation, potentially via arachidonic acid pathway inhibition and other anti-thrombotic effects.
  • Human trials show decreased LDL cholesterol and blood pressure with green tea consumption.

Anti-Inflammatory Effects:

  • Green tea reduces inflammatory mediators like IL-1β, IL-6, IL-8, TNF-α, COX and iNOS. It also inhibits neutrophil migration and adhesion.
  • Researchers have demonstrated the anti-inflammatory effects in arthritis models and suggest their relevance for other chronic inflammatory diseases.

Antimicrobial Properties:

  • Green tea exhibits antibacterial, antiviral and antifungal effects against many pathogens like E. coli, influenza and Candida.
  • Catechins damage microbial cell membranes and inhibit enzymes like protein tyrosine kinase, DNA gyrase and cysteine proteinases.

Oral Health:

  • Green tea polyphenols inhibit growth, acid production and biofilm formation by dental plaque bacteria like Streptococcus mutans.
  • Epidemiological studies associate green tea consumption with decreased dental caries and periodontitis.

The antioxidant activity of green tea catechins is a key mechanism underlying its health benefits. Catechins scavenge reactive oxygen species, chelate transition metals like iron and copper, and boost endogenous antioxidants. This provides protection against oxidative damage implicated in chronic diseases.

Many studies use test tubes and animals. However, an increasing number of trials involving humans demonstrate that green tea offers significant health benefits. A moderate intake of 1-2 cups daily may be adequate for a preventive effect.

However, human studies have shown mixed results, potentially due to differences in metabolism and lifestyle factors across populations. More clinical trials are needed to substantiate health claims, determine optimal dosing and assess relative catechin bioavailability from different green tea preparations.


Top Eight Health Benefits of Green Tea – Dr. Berg

Scientific Studies

An Update on the Health Benefits of Green Tea

Benefits of Green Tea: A Review

For an overview of the different types of tea, please follow this link (links to types of tea page)

For the health benefits of other teas, please follow these links:

Tea Health

Black tea health benefits

Herbal tea health benefits

Oolong tea health benefits

Puerh tea health benefits

White tea health benefits