HEALTH TALK
Green Tea (Photo – rivertea.com).
Green tea is prepared from the steamed and dried leaves of Camellia sinesis, a large shrub native to eastern Asia.
By H. S. Nemr
Source and chemical components
Because of the preparation process, the properties of green tea are similar to those of the fresh leaves and are different from those of black tea.
Green tea contains polyphenols (catechins), tannins, flavonoids, and methylxanthines (caffeine).
Actions
Green tea is believed to have a chemo-protective effect attributed to its content of polyphenols.These agents are believed to inhibit cell proliferation and tumor promotion. In vitro studies of green tea polyphenols induced programmed apoptosis (cell death) in human cancer cells (Hibasami et al.,1998; Ahmad et al., 1997). The fluoride and tannins in green tea are believed to decrease the formation of dental caries. Caffeine in green tea produces CNS stimulation.
Boseong Green Tea Field (Photo – Yellow Bellied Mustard Frog).
Therapeutic and reported folk uses
Therapeutic claims for green tea include the prevention of cancer, atherosclerosis, hypercholesterolemia, and dental caries. It is also promoted as having antibacterial, astringent, diuretic and chemoprotective effects.
Dosage
Epidemiological studies have suggested possible effects from drinking 6 cups daily; pharmacokinetic studies indicate that 3 capsules of green tea extract provide adequate plasma levels.
Adverse reactions and precautions
Immunoglobulin E mediated allergic reactions have been reported in patients with green tea asthma.
Interactions
Warfarin: Green tea can be a significant source of Vitamin K and thus can antagonize the effects of warfarin.
Ginseng containing products should be avoided in pregnancy and during breastfeeding.
H.S. Nemr is a graduate of BAU pharmacy school. He is currently a medication safety officer at Johns Hopkins Aramco Healthcare system.
References
- Professional’s Handbook of Complementary Alternative Medicines, 2nd edition.
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