Green tea is made from the dried leaves of the Asian plant Camellia sinesis and is
drunk widely across Asia. The rates of many cancers are much lower in Asia than
other parts of the world, which has led some to link the two. Laboratory studies
have shown that extracts from green tea, called polyphenols, can stop cancer cells
from growing. But results from human studies have been mixed. Some have
shown a protective effect while others have failed to find any evidence of protection.