Green tea (Camellia sinensis) for the prevention of cancer.

Filippini T, Malavolti M, Borrelli F, Izzo AA, Fairweather-Tait SJ, Horneber M, Vinceti M

The Cochrane database of systematic reviews · March 2, 2020

Background: Tea is one of the most commonly consumed beverages worldwide. Catechins are powerful antioxidants, and laboratory studies have suggested that these compounds may inhibit cancer cell proliferation. Some epidemiological studies have suggested that green tea may have cancer-preventative effects. Objectives: To assess possible associations between green tea consumption and the risk of cancer incidence and mortality. Main Results: We included in total 142 completed studies (11 experimental and 131 nonexperimental). In nonexperimental studies, we included over 1,100,000 participants from 46 cohort studies and 85 case-control studies. When comparing the highest intake of green tea with the lowest, we found a lower overall cancer incidence (summary RR 0.83, 95% CI 0.65 to 1.07), based on three studies, involving 52,479 participants (low-certainty evidence). Conversely, we found no association between green tea consumption and cancer-related mortality (summary RR 0.99, 95% CI 0.91 to 1.07), based on eight studies and 504,366 participants (low-certainty evidence). Authors' Conclusions: 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.

PMID: 32118296 · DOI: 10.1002/14651858.CD005004.pub3