Like most Americans I tend to be more of a coffee drinker, rather than a tea drinker. However a few recent journal articles on the benefits of green tea has had me sipping on a hot cup of green tea in the afternoon lately.
A recent study in the Chinese Medicine Journal reviewed the published medical literature dating back to 1980 regarding the health benefits and possible risks of green tea consumption. Green tea is thought to have many benefits including the prevention and/or reduction of risk of developing certain types of cancers and heart disease. Green tea is also thought to have anti-inflammatory and antibacterial and antiviral activity. Additionally green tea may even lower cholesterol. The main reason for these benefits are thought to be high flavanol or flavonoid content of fresh green tea.
Green tea (as well as other types of teas) comes from the leaves of the plant Camellia sinesis. One reason believed to account for the difference in health benefits of green tea versus the other teas has to do processing methods. The green tea leaves are steamed after harvesting while black tea and other teas undergo a fermentation process that breaks down the flavaoid compounds which may affect the biological physiological activity of these compounds.
Green tea may have some benefit with increasing in bone density. One study found that the consumption of green tea was an independent factor protecting against the risk of hip fractures regardless of smoking status or hormone replacement therapy. (Muraki 2003)
Green tea components have been shown to improve glucose metabolism and animal studies of type 2 diabetes as well as protecting inserted into the pancreas and animal studies. Other studies looking at the effect of the components of green tea in obesity and diabetes and animal studies have also demonstrated improvement of blood glucose levels and a reduction in body weight in mice. A few studies looking at green tea consumption in men indicated increased fat oxidization in the group of men that consumed green tea, however these were smaller studies and larger studies still need be done.
There are some adverse effects of consuming too much green tea. Different individuals may metabolize the components differently based on genetic makeup. One component of green tea can be toxic to liver cells if taken any large dose and some people may be sensitive to increase caffeine levels.
It will be interesting over the next couple years as more human-specific studies come out looking at the health benefits of green tea
