Energy
Green tea extract
Green tea extract supplies catechins, but low pre-workout doses have no proven performance benefit.
How it counts: Not part of the score
We show it on the label and count it as disclosed, but it never affects Dose, any sub-score or the grade. The basis below explains why.
- Clinical dose
- No established clinical dose
- Safety ceiling
- —
- Evidence
- weak
- Category
- Energy
Evidence summary
Research confidence: low
No reference dose. Green tea extract supplies catechins such as EGCG; in one study about 366 mg EGCG taken over the day before exercise raised fat burning during cycling by 17% (Venables 2008), but a larger trial of a decaffeinated extract found no effect (Randell 2014), and neither measured performance. The 45 mg on these labels provides about 20 mg EGCG, under a tenth of the studied amount. An extract that is 98% polyphenols can contain at most about 1 mg of caffeine per 45 mg, which is negligible, though supplement labels are not always accurate about caffeine.
Research sources
- Green tea extract ingestion, fat oxidation, and glucose tolerance in healthy humans (Venables et al., Am J Clin Nutr 2008)(opens in new window)
- Variable duration of decaffeinated green tea extract ingestion on exercise metabolism (Randell et al., Med Sci Sports Exerc 2014)(opens in new window)
19 men, decaffeinated green tea extract for 1, 7 or 28 days: no change in fat burning during exercise vs placebo, contradicting the earlier positive report.
- Scientific opinion on the safety of green tea catechins (EFSA ANS Panel, EFSA Journal 2018)(opens in new window)
Supplement doses of 800 mg EGCG/day or more for 4+ months were associated with liver-enzyme rises in a small share of people; no safe level could be set from the data. Label doses (~20 mg EGCG) are far below this.
- Catechin and caffeine content of green tea dietary supplements and correlation with antioxidant capacity (Seeram et al., J Agric Food Chem 2006)(opens in new window)
19 green tea supplements tested: label claims often did not match measured catechin content, and only 7 of 19 declared caffeine, so the caffeine in a given extract can't be read off the label.