Through archaeological carbon dating, it was discovered that Green Tea leaves were first boiled in water over 500,000 years ago. It has been cultivated in India, China, and Japan for hundreds of centuries and has been used for at least five thousand years to support digestion, promote a healthy cardiovascular system, promote healthy metabolism of sugars, provide support for clear thinking and encourage an energetic lifestyle. Its consumption worldwide is second only to water. Green tea comes from the unfermented leaves of the Camellia sinensis shrub, while oolong tea is partially fermented, and black tea is fully fermented and has the highest caffeine and lowest antioxidant activity. Green tea has been shown to have the some of the highest antioxidant activity of any plant known. It was shown to have more antioxidant capacity than both Vitamin C and Vitamin E in a study conducted in 1989.