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 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 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 (see separately). 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.
There are many herb teas on the market today, each having a particular health benefit. One tea, however, stands head and shoulders above the rest as an all-round healthy alternative and that is Rooibos tea.
Rooibos is a member of the legume family, Fabaceae/Leguminosae Aspalathus linearis, and grown only in Cedarburg, a small area north of Cape Town, South Africa. Also known as the red bush, Rooibos is shrubby in nature with a smooth-barked main stem that subdivides into strong offshoots which eventually produce soft, needle-like leaves that can reach ten centimeters in length. Locals have long known that these leaves made a tasty, aromatic tea.
The health benefits of Rooibos tea are significant; moreso even than green tea. Before listing what the tea does have, what it does not have is equally significant. Rooibos does not contain oxalic acid; therefore, it can be safely consumed by those prone to kidney stones.
Rooibos also does not have caffeine; unlike green tea, which has 30-60 mg in 8 oz. and coffee which has over 100 mg in the same amount. For generations, mothers have instinctively known about its lack of caffeine and anti-spasmodic effects for they have given Rooibos to their colicky infants and have used it to supplement their breastmilk. Since Rooibos soothes the central nervous system, it is not only good for babies but also for adults who are bothered by digestive upsets, headaches, insomnia, stress, and irritability.
What Rooibos does contain are about 37 powerful antioxidants (flavonoids) 50 times that of green tea. Antioxidants are significant in the fight against free radicals that weaken the immune system, promote aging, and contribute to a wide variety of diseases. One antioxidant, aspalathin, is found only in Rooibos and appears to be stronger than the more commonly known ones of quercetin, rutin, and luteolin. These three are known to be antispasmodic, anticancer, anti-inflammatory, anti-thrombotic, anti-allergic, and anti-viral. Allergies sufferers, especially those with asthma or hay fever, often cannot consume herb teas but find they have no problem with Rooibos tea.
Japanese scientists have shown that Rooibos has benefits relating to constipation, blood sugar levels, poor circulation, and skin diseases. A study published in the Journal of Physiological Research (Prague; 2003:52(4):461-6), showed that Rooibos tea has a significant protective effect on the liver and recommended that it be included in the diets of those with liver disorders. Various studies carried out by several South African universities showed that Rooibos contains a significant quantity of minerals (calcium, potassium, magnesium, manganese, copper, iron, and zinc, as well as trace amounts of the electrolyte, sodium, and natural fluoride), vitamin C, and alpha-hydroxy acid (something that promotes healthy skin).
Although Rooibos contains a small amount of tannin, the amount is so low that it does not affect the absorption of iron but may, in fact, improve absorption. Small amounts of tannin can have some health benefits, like stimulating the immune system, but large amounts can cause a decrease in food intake and absorption, growth rate, and protein digestibility. Some of the beverages rich in tannins include black, green, peppermint and chamomile (Matricaria recutita) teas, coffee, chocolate, and red wine. Because of the tannins, such beverages will usually have a bitter taste; but Rooibos has a natural sweetener that offsets any bitterness that might come from its small amount. This natural sweetener is also free of calories; a boon to diabetics and those on diets.
Rooibos tea is very versatile. It can be taken warm or cold and added to any recipe. It is especially good when it is substituted for water in a fruit/vegetable drink or when soaking dried fruits. It is also good for plants and pets.
For more information on Rooibos tea and its antioxidant and antimutagenic properties, read this detailed analysis provided by the American Botanical Council on a site called HerbalGram.