Supplements

green tea decreases cancer risk

In plain terms: Does green tea prevent cancer?

Contested Supplements 🔬 Includes disconfirming

RefutedContestedStrong support

consensus score 0.19

Not broadly. The Cochrane review of this question - one review in two editions, 2009 and its 2020 update - found no convincing overall cancer-prevention effect. Some individual (mostly observational) studies link green tea to lower risk of specific cancers - stomach, oral, breast, esophageal - but that evidence is weaker and inconsistent. Not a reliable cancer preventive.

📅 Last reviewed: 2026-07-15 ⓘ

Evidence ladder

How far up the ladder this claim has climbed. A high consensus on a low rung means "consistent so far," not "proven in people."

Top evidence so far: All trials, pooled (Meta-analysis)

MechanismIn-vitroAnimalObservationalRCTMeta-analysis

How the studies fall

9 support 2 contradict 2 tested null 1 mixed · 14 sources, 11 independent groups

What the evidence shows

The broad 'green tea prevents cancer' claim is NOT supported by the strongest evidence. The Cochrane review judged it insufficient/inconsistent; the largest dose-response meta-analysis across five cancers found no overall benefit (and black tea was a breast-cancer risk factor); breast and colorectal analyses are null. An umbrella review found 'convincing' evidence only for oral cancer.

Cochrane has no ruling yet see how our grade compares ▾

Cochrane · Low to very low certainty (GRADE) across outcomes Not directly comparable

“Overall, findings from experimental and nonexperimental epidemiological studies yielded inconsistent results, thus providing limited evidence for the beneficial effect of green tea consumption on the overall risk of cancer or on specific cancer sites. A beneficial effect of green tea consumption on cancer prevention remains unproven so far.”

Not directly comparable: their review asks a different question or reports an outcome we do not grade, so it neither corroborates nor contradicts this claim.

What is Cochrane, and why trust it?

Cochrane produces systematic reviews: instead of running a new study, they gather every trial ever done on a question, judge how well each was run, and pool the results. They take no commercial or industry funding, which is why the medical community treats their reviews as a gold standard — and why we check our own verdicts against theirs.

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The evidence (17)

Source	Grade	Stance	Quality	Finding
Kim TL, Jeong GH, Yang JW, Lee KH, Kronbichler A, van der Vliet HJ, Grosso G, Galvano F, Aune D, Kim JY, Veronese N, Stubbs B, Solmi M, Koyanagi A, Hong SH, Dragioti E, Cho E, de Rezende LFM, Giovannucci EL, Shin JI, Gamerith G 2020 · Adv Nutr	observational	mixed	moderate	Umbrella review 64 observational studies: only ORAL cancer met 'convincing' criteria (OR 0.62); most other sites weak/non-significant.
He JJ, Zhang YF, He ZH, Zheng L 2025 · Frontiers in oncology	animal	supports	moderate	Systematic review/meta-analysis of 20 preclinical studies (mouse/rat models) of green tea extract/EGCG in breast, ovarian, uterine cancer; pooled tumor volume reduced (Hedge's g=-2.332) and tumor weight reduced (Hedge's g=-2.105), EGCG null
Altinoz HB, Sanlier N 2026 · BMC cancer	observational	mixed	low	Narrative review of green tea catechins and prostate cancer; preclinical/in-vitro mechanisms promising but abstract states clinical evidence remains limited due to few, small human trials.
Yu F, Jin Z, Jiang H, Xiang C, Tang J, Li T, He J 2014 · BMC Cancer	meta-analysis	contradicts	high	Dose-response meta 41 cohorts (3M participants, 5 cancers): NO overall inverse association; black tea was a breast-cancer risk factor (RR 1.18).
Zhao H, Mei K, Yang L, Liu X, Xie L 2021 · Nutrition	observational	supports	moderate	Dose-response meta: inverse green tea - esophageal cancer.
Funabashi O, Sakaniwa R, Kawasaki R, Tamakoshi A, Iso H 2026 · Asian Pacific journal of cancer prevention : APJCP	observational	supports	moderate	JACC prospective cohort of 41,999 Japanese adults; green tea consumption inversely associated with liver cancer incidence, HR 0.61 (95% CI 0.40-0.95) for ≥7 cups/day vs <1 cup/day (p-trend=0.029).
Zhang Y, Xu Q, Hu J, Zhang F, Yu Y, Ma L 2025 · Am J Chin Med	observational	supports	high	Meta 43 studies: green tea RR 0.91 overall; EGCG RR 0.72; prostate 0.43, oral 0.44.
Wang S, Li X, Yang Y, Xie J, Liu M, Zhang Y, Zhang Y, Zhao Q 2021 · Public Health Nutr	observational	tested-null	moderate	Network meta (45 studies, 3.3M): tea/coffee NOT associated with lower overall breast cancer; only a weak ER-negative signal at >=5 cups/d.
Najaf Najafi M, Salehi M, Ghazanfarpour M, Hoseini ZS, Khadem-Rezaiyan M 2018 · Phytother Res	observational	supports	moderate	Meta 14 studies: green tea - breast cancer OR 0.81.
Zheng S, Suo X, Li C, Lu S, Han J, Bo Y, Guo J 2025 · Frontiers in nutrition	observational	supports	moderate	UK Biobank prospective cohort, 276,209 participants, 3,821 incident lung cancers; tea consumption associated with lower lung cancer risk (e.g. HR 0.67, 95% CI 0.60-0.76 for 2-3 cups/day vs non-drinkers), non-linear dose-response.
Gianfredi V, Nucci D, Abalsamo A, Acito M, Villarini M, Moretti M, Realdon S 2018 · Nutrients	observational	supports	moderate	Meta 13 studies: green tea inversely associated with breast cancer OR 0.85.
Boehm K, Borrelli F, Ernst E, Habacher G, Hung SK, Milazzo S, Horneber M 2009 · Cochrane Database Syst Rev	observational	contradicts	high	Cochrane review (RCTs + observational): evidence insufficient/inconsistent; no established site-specific cancer-prevention effect.
Ishikawa H, Mutoh M, Yamane T, Wakabayashi K, Hirata K, Iwama T, Nakamura T, Tomita N, Matsuyama Y, J-FAPP Study I Group 2026 · Genes and environment : the official journal of the Japanese Environmental Mutagen Society	RCT	mixed	low	Double-blind RCT (J-FAPP Study I), 80 FAP patients randomized to green tea extract (1.5g/day, 2 years) vs placebo; colorectal polyp enlargement risk ratio 0.43 (95% CI 0.12-1.49, p=0.16).
Liu S, Chen J, Wang Y, Xu Y 2023 · Nutr Hosp	observational	supports	low	Network meta 14 RCTs (73,365 men): ranked green tea catechins highest for reducing prostate cancer risk, but authors say more quality evidence needed.
Huang Y, Chen H, Zhou L, Li G, Yi D, Zhang Y, Wu Y, Liu X, Wu X, Song Q, Liu L, Yi D 2017 · Public Health Nutr	observational	supports	moderate	Dose-response meta: inverse green tea - gastric cancer.
Myung SK, Bae WK, Oh SM, Kim Y, Ju W, Sung J, Lee YJ, Ko JA, Song JI, Choi HJ 2009 · Int J Cancer	observational	tested-null	moderate	Meta: stomach cancer case-control OR 0.73 (protective) but cohort RR 1.04 (null) - the classic design split.
Filippini T, Malavolti M, Borrelli F, Izzo AA, Fairweather-Tait SJ, Horneber M, Vinceti M 2020 · Cochrane Database Syst Rev	observational	contradicts	high	Cochrane (updated): no convincing evidence green tea reduces cancer incidence; low-certainty subgroup signals.

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