From P.D. Mangan’s book “Best Supplements for Men“:
Green tea, which is commonly drunk in China and Japan, is associated with lower rates of cancer, about 30% lower in those who drank the highest amounts of green tea compared to the lowest. Deaths from cardiovascular disease were about 25% lower in the highest consumption group versus the lowest. This is of course epidemiological evidence, meaning that it can’t show whether green tea actually prevented disease, or that there’s some other connection such as that heather people drank more green tea.
Laboratory and other evidence, however, provides some good reasons to think that green tea is the real deal when it comes to sides prevention.
A recent study of the elderly in Singapore found tea consumption linked to much lower risk of neurocognitive decline in women and carriers of the “dementia gene” APOE ε4.
P.D. suggests that the health-promoting dose of tea is 3 to 5 cups a day, and black tea may be just as good as green.