The Active Fraction

Green tea's bioactivity is concentrated in its catechins - flavan-3-ol polyphenols, chiefly epigallocatechin gallate (EGCG), plus EGC, ECG and EC. EGCG is both the most abundant and the most researched, which is why it anchors most standardised grades. The summary below cites controlled trials and meta-analyses rather than single observational studies.

Antioxidant Capacity

Green tea catechins are potent dietary antioxidants that scavenge free radicals and support cellular defence; green tea is one of the richest practical sources of these compounds. This antioxidant action underlies much of the broader interest in the extract.

Reference: Higdon JV & Frei B, 2003; Critical Reviews in Food Science and Nutrition.

Thermogenesis & Fat Oxidation

A controlled study reported that green tea extract increased 24-hour energy expenditure and fat oxidation beyond what its caffeine content alone would explain - implicating the catechins themselves as the active fraction. This is the mechanistic basis for green tea's use in thermogenic and metabolic formulas.

Reference: Dulloo AG et al., 1999; American Journal of Clinical Nutrition.

Weight Management

A meta-analysis of randomised trials found that catechin-caffeine mixtures produced a modest but statistically significant effect on body weight and weight maintenance. The effect is real but moderate - useful framing for honest product claims.

Reference: Hursel R et al., 2009; International Journal of Obesity.

Cholesterol & Lipids

A meta-analysis of controlled trials reported that green tea catechins significantly lowered total and LDL cholesterol, consistent with a cardiovascular-support role for the polyphenols.

Reference: Zheng XX et al., 2011; American Journal of Clinical Nutrition.

Blood Pressure

A meta-analysis of randomised trials reported small but significant reductions in systolic and diastolic blood pressure with green tea intake, attributed in part to improved endothelial function.

Reference: Khalesi S et al., 2014; Journal of Hypertension.

Focus & Cognition

The combination of L-theanine and caffeine native to green tea has been shown to improve attention and alertness in controlled studies - the basis for green tea's place in nootropic and calm-energy formulations.

Reference: Owen GN et al., 2008; Nutritional Neuroscience.

Safety guardrail - EGCG and the liver: EFSA's 2018 assessment concluded that EGCG doses at or above 800 mg/day from supplements are associated with a hepatic-safety signal (raised liver transaminases). The EU subsequently set conditions on green-tea catechins (Regulation (EU) 2022/2340) including warning statements. Formulators should calculate and declare the finished-product EGCG dose and keep it within applicable limits.

Selected References

This article is for B2B formulation and educational purposes only. It is not medical advice and does not constitute a health claim. Finished-product claims must be independently substantiated and compliant with the regulations of each destination market.