When buying green tea, make sure it is packed in air tight package. Antioxidants in green tea are sensitive to light and oxygen.

Also, once you break the seal, store your green tea in a sealed container in dark and cool areas. According to a 2009 study published in the Journal of Food Science, the antioxidants (especially catechins which are linked with a reduced risk of several types of cancer) in the green tea lose their value by 32 percent after 6 months.