Green tea is an evergreen shrub that has long been used in much of the world as a popular beverage and a respected medicinal agent. An early Chinese Materia Medica lists green tea as an agent to promote digestion, improve mental faculties, decrease flatulence and regulate body temperature. The earliest known record of consumption is around 2700 B.C. Ceremonies, celebrations, relaxation time and ordinary meals usually consist of tea in most parts of the world, except the United States, where coffee has become the most popular beverage. Unlike black tea (also Camellia sinensis) which is produced by oxidizing the young tea leaves, green tea is produced from steaming fresh leaves at high temperatures, thereby inactivating the oxidizing enzymes and leaving the polyphenol content intact.
Green tea is an antioxidant and is used in promoting cardiovascular health and reducing serum cholesterol levels in laboratory animals and humans. Studies suggest that green tea contains dietary factors that help decrease the development of some infectious diseases and dental caries. Green tea has diuretic, stimulant, astringent, antibacterial, antifungal, anticarcinogenic, thermogenic and anti-inflammatory properties. Green tea has also been reported to enhance immunity.
Findings from a recent study suggest that green tea may protect DNA from damage associated with aging. The placebo-controlled, cross-over supplementation study included 18 healthy volunteers who were randomly assigned to receive two cups of green tea or water every day for 4 weeks. A six-week washout period separated each four-week intervention, and blood and urine samples were collected before and after each intervention. The results of the study found a 20% reduction in levels of DNA damage, while measures of whole-body oxidative stress were unchanged. These findings indicate that regular consumption of green tea may protect against damage at a genetic level and slow the aging process.1
1. Han KC, Wong WC, Benzie IF. Genoprotective effects of green tea ( Camellia sinensis) in human subjects: results of a controlled supplementation trial. Br J Nutr. Sep2010:1-8.