Green Tea is made from the natural dried leaves of the tea plant, Camellia sinensis. Black tea is oxidized green tea.
Green tea contains polyphenols, which are a form of bioflavonoids that occur naturally in certain foods and which work as antioxidants to protect the body from oxidative stress that causes disease. Animal tests appear to show that Green Tea polyphenols have anti-inflammatory properties. L-Theanine (or Theanine) is an amino acid found in in the leaves of green tea. In animal tests, Theanine has been shown to increase levels of the neurotransmitter chemicals GABA and dopamine, which may explain its purported mood-enhancing and stress-reducing effects in humans. Indeed, in Japan theanine is added to soft drinks and chewing gum for the purpose of inducing relaxation.
Cooled, decaffeinated green tea is used by some naturopathic avian vets to boost the immune system, and to relieve anxiety and behavioral problems.