Tea is in the news today because of a research report that experimental cancer was reduced 40 per cent in rats given green tea to drink. What are the active ingredients? It is believed that tannins in the tea are responsible. The paradox here is that some tannin are also suspected of causing esophageal cancer in those who drink tea to excess over long periods of time.
We might properly credit Genghis Khan with introducing tea to Western Civilization. Tea served the Armies of the Great Khan very well: the caffeine derivatives and ephedrine in Chinese teas are well-known performance boosters. More important, tea is an infusion of leaves in boiling water. Boiling the water also protected these warriors from epidemics of dysentery that otherwise might have discouraged their dreams of conquest. It is not far-fetched to claim that tea was a major weapon in the armory of Genghis Khan!
Tea has always been a beverage to be enjoyed for pleasure. In the first place it is tastier than water, and as we have observed, safer. If you were pro-fluoridation, you would recommend tea for infants and children, since it is a natural source of fluoride. Two cups of tea made with non-fluoridated water contains about 1 mg of fluoride, which is considered to be optimal. Of course, if your water is fluoridated at the prescribed level of 1 part per million (1 mg per liter, that is, about 4 cups) then two cups of tea actually provides 1.5 mg of fluoride and 4 cups would contain 3 mg, which is getting close to the limit of safety for long term fluoride intake.
Tea also contains enzymes that inactivate thiamin, vitamin B1. Hence if one drinks tea in large amounts, one should be aware of sources of the vitamin: meat, nuts, whole grains, and wheat germ, yeast. Loss of thiamin is compounded by sugar, which uses up the vitamin in the chemical activities of the body. Adding heaps of sugar to iced tea is not a good idea.
With these modest warnings in mind, it is safe to say that tea is good for you. It has nutritional value and provides some magnesium and potassium. On the other hand, again, the tannins bind to minerals, such as iron and calcium. If you are iron deficient, tea is not for you. Some of us may think of tea as a feminine drink and coffee as more masculine. Actually, tea is a better drink for men because it hinders absorption of iron, a mineral that can accumulate to excess in men.
The tannins in tea are released at lower temperature than the flavorful substances, so if drink tea for the pleasure of its flavor then bring the water to boil before adding to the tea. Don't over-heat or simmer very long or the tannins will overtake the flavor. On the other hand, if you want a medicinal brew, soak it at low heat or simmer it longer, until it makes your mouth pucker at the taste of it.
Tannins are astringent; they bind to proteins in the mucous membranes of the mouth, just as they bind to the membranes of certain microorganisms, particularly yeasts. And this is a major medicinal use for tea: as a safe antibiotic against yeast, including Candida albicans. In my practice make good use of tannin, which is taken as a capsule for intestinal problems, a gargle for coated tongue or oral thrush, and as a douche for monilia. In each case it offers advantages.
Finally, tannins attach to various toxins and antigens in the gut, thus protecting the mucosa from injury in case of infection. It also prevents systemic invasion of the body by sealing damaged cells. In short, tea contains tannins that are well suited as first-line agents in case of diarrhea.
Now we see that tea has nutritional and medicinal value as well but that is perhaps of more interest to the physician. Let's hear it first for pleasure, thrice over.
©2007 Richard A. Kunin, M.D.