A Note on Tea

TEA originated in China several thousand years ago. There are two basic kinds of tea -- black and green -- containing more than 300 known compounds. The difference between the black and green tea is generated during the manufacturing process. Oolong tea is semi-fermented but is
closer to black tea than green.

Black Tea
Black tea undergoes a fermentation step whereby enzymes, present in the tea flush, convert certain components present (for example, proteins, amino acids, fatty acids, and polyphenols) into compounds that are responsible for the characteristic aroma and flavor of black tea. India
and Sri Lanka are the major producers of black tea.

Green Tea
Green tea manufacturing eliminates the fermentation process, but still inactivates the enzymes present. The initial step is subjecting the flush to either the Japanese process of steaming, or the Chinese process of dry heating. Both countries are the world's major producers of green tea.

Green tea has, for some inexplicable reason, attained "health food" status, even though it has some decidedly "unhealthy" properties. Green tea contains triterpene saponins, which have the ability to dissolve erythrocytes (a red blood cell), even when highly diluted. Green tea also has a high fluroide content (130-160mg/kg), as well as potassium and aluminum ions. Both black and green teas contain caffeine. Iced tea can contain as much as 70 mg. of caffeine per cup, and even decaffeinated is not totally free of caffeine. Caffeine was first discovered in tea in 1827 and named theine. Later, when it proved to be chemically identical to caffeine, the name was dropped, leaving caffeine as the name of similar compounds.

Both types of tea contain large amounts of catechin tannins (10-25%), with those in green tea being higher than in black. Fermentation (black) partially changes catechins into oligomeric quinones with tannin characteristics. Tannins are known to decrease the digestibility of proteins. A cup of tea contains lesser amounts of caffeine than coffee, but the tannin content is much higher. Although tannins have both anticancer and carcinogenic properties, what activates one over the other is thought to lie within an individual's own chemistry makeup.

Both also contain xanthine alkaloids (theobromine, theophylline, dimethylxanthine, xanthine, and adenine). Xanthine is a precursor to uric acid -- also found in many organ meats -- which causes kidney stones and gout. Closely related to caffeine, theobromine has diuretic properties, is an arterial dilator, and is a central nervous system stimulant. It is widely consumed, not only in tea, but in coffee, cola, and chocolate. It is also highly toxic to dogs. The USDA recently added values from research conducted by the Agricultural Research Service (1994-96 and 1998) indicating levels of caffeine and theobromine consumed by children through nine years of age. The average intake was 13.9 mg., with most being consumed in carbonated drinks and tea, with chocolate running a close second. The giving of green tea to infants and children is popular with mothers anxious to see that their children attain higher standards of health. The average intake of theobromine levels in these same children were reported to be 42.5 mg. or 23.8 mg./1000kcal. Theophylline targets the heart, bronchia, and kidneys, and is the most common medication used
for asthma and COPD patients.

Precautions for green tea users are noted in the Herbal PDR. Those who have a weakened cardiovascular system, renal diseases, thyroid hyperfunction, elevated susceptibility to spasms or certain psychic disorders (for example, panic or anxiety), or who are pregnant or nursing should avoid its use. Long term usage produces the same symptoms as other caffeinated drinks do: restlessness, irritability, sleeplessness, heart palpitations, vertigo, vomiting, diarrhea, loss of appetite, and headaches. The resorption of alkaline medications can be delayed because of chemical bonding with the tannins. An overdose is considered to be greater than 300 mg. caffeine or five cups of tea, which can lead to symptoms such as restlessness, tremors, and an elevated reflex excitability. The first signs of poisoning are vomiting and abdominal spasms.

Green tea may also interfere with the absorption of atropine, if taken orally. Large quantities may also increase the activity of Warfarin (Coumadin), which is a blood thinner. In addition, tannin-containing foods have been known to affect the absorption of Codeine and Cardec medications.