Green tea is different from black and oolong teas, as it does not undergo the same oxidation process. And while it originated in China, its cultivation and use has spread throughout the world.
Polyphenols found in green tea include epigallocatechin gallate (EGCG), epicatechin gallate, epicatechins and flavanols, which are under laboratory research for their potential effects in human subjects. Other components include three kinds of flavonoids, known as kaempferol, quercetin, and myricetin. The typical content of flavonoids and catechins in a cup of green tea is higher than that in the same volume of other food and drink items that are traditionally considered to promote health.
There are many health benefit claims to drinking green tea due to its antioxidant content and these claims continue to show positive results in many ways like heart health that shows green tea can reduce cardiovascular disease*, and it also shows potential as a cancer-fighting helper*.
https://www.health.harvard.edu/heart-health/green-tea-may-lower-heart-disease-risk
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2748751/
https://www.healthline.com/health-news/drinking-tea-can-cut-risk-of-heart-disease-and-stroke-emb-midnight
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5824026/
*These statements have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure or prevent any disease.