Dr. Smith alleges that “tea promotes all vital actions, the action of the skin particularly being increased and that of the bowels lessened, the kidney secretions are also affected, and the urine, perhaps, somewhat diminished, the latter being uncertain.” Other recent authorities agreeing that the direct effect of tea upon the human system is to increase the assimilation of food, both of the heat-giving and flesh-forming kinds, and that with an abundance of food it promotes nutrition, while in the absence of sufficient food it increases the waste of the tissues and body generally. An infusion of cold tea has been known to check violent retching and vomiting, while a very hot one will prove beneficial in severe attacks of colic and diarrhœa, having a specific action on the kidneys and urine. An application of infused tea leaves will subdue inflammation of the eyes produced by cold or other causes, but should be applied only and allowed to remain over night; and people who travel much will find a supply of tea a valuable accompaniment, as it is found to improve the taste and counteract the effects of the most brackish water, proving efficient also in preventing the dysenteric and diarrhetic results produced by the frequent and extreme changes of drinking waters. It is for the purpose of qualifying the water expressly that tea is so generally used in China, as very little good drinking water is to be met with in any part of that country.
With brain-workers it has always been a favorite beverage, the subdued irascibility, the refreshed spirits, and the renewed energies which the student so often owes to it, have been the theme of many an accomplished pen. Yet it is impossible to speak too strongly against the not uncommon habit frequently adopted by ardent students when prosecuting their studies far into the night, to resist the claims of nature for repose, and keep off the natural sleepiness by repeated libations of tea. That it answers the purpose for the time being cannot be denied, but the object is often attained at a fearful price, the persistent adoption of such a practice being certain to lead to the utter destruction of the health and vigor of both body and mind. Less injury in such cases will result from the use of coffee, there being this difference between the morbid states of the nervous system produced by coffee and that resulting from tea. The effect of the former generally subsides or disappears entirely on relinquishing its use, while that caused by tea is more permanent and often incapable of being ever eradicated.
That tea does not suit all temperaments, constitutions and all ages is no valid argument against its general use. That it is less adapted to children than adults is admitted; indeed, for very young children it is entirely improper, producing in them, like all narcotics, a morbid state of the brain and nervous system in general. It is also unsuited to those of an irritable temperament as well as for those of a leuco-phlegmatic constitution, such persons illy bearing much liquid of any kind, particularly in the evening, prospering best on a dry diet at all times, and to which young children especially should be strictly confined. Briefly it may be summed up that tea is best suited to persons in health, the plethoric and sanguine, and upon which principle it is the proper diet at the beginning of fevers and all inflammatory complaints. Besides the more obvious effects with which all who use it are familiar, tea saves food by lessening the waste of the body, thus nourishing the muscular system while it excites the nervous to increased activity, for which reason old and infirm persons derive more benefit and personal comfort from its use than from any corresponding beverage. To the question “does tea produce nervousness?” the answer is “in moderation, emphatically No!” One to two cups of tea prepared moderately strong, even when taken two to three times per day will not make any one nervous, but when drunk to excess it undoubtedly will. Tea-testers and experts who are tasting it all the time, day in and day out, for the purpose of valuing it, are frequently made nervous by it, soon recover by a little abstinence. Tea, like liquor and drugs, when taken in moderate quantities, produce one effect, but when used in large and immoderate quantities produce just the contrary result. China and Japan teas, containing more theine and less tannin, are consequently less hurtful and more refreshing than India and Ceylon teas, which contain nearly double the quantity of tannin, the astringent property to which India and Ceylon teas owe the harsh, bitter taste so often complained of in them, and which is undoubtedly the unsuspected cause of the indigestion and nervousness produced by their use.
DIETICAL PROPERTIES.
That the universal employment of tea has displaced many other kinds of food is certain, and regarding its dietical properties much has been written for and against. While some physicians have praised its value as an article of food, on account of the large proportion of nitrogen which it contains, others have as strenuously maintained that it is non-nutritious, and does not serve as a substitute for food, and that the only beneficial properties it contains are due to the milk and sugar added in its use. So that in considering the nourishing effects of tea, the nutriment contained in the milk and sugar certainly must not be overlooked, neither must the powerful influence of the heat of the steaming draught be forgotten. According to the chemical classification of food, the “flesh formers” contained in tea of average quality is about 18, and the “heat givers” 72 per cent., water and “mineral matter” being divided between the residue, the several constituents as they are found in one pound of good tea being as follows:—
The use of theine as an article of diet has not so far been satisfactorily determined; but that it is a question of no mean interest is obvious when we consider that it is found to exist in so many plants, differing widely in their botanical origin and yet all instinctively used for the same purpose, by remotely situated nations, for the production of useful, agreeable and refreshing beverages.
By taking the normal temperature of the human body at 98°, it follows that where food is taken into the stomach of a lower temperature than that of the body it must necessarily abstract heat from the stomach and surrounding tissues, so that where the practice of taking cold food becomes habitual depression occurs and the stomach is consequently disordered, and the system must make good this heat lost in raising the temperature of cold food or else suffer. The body demanding food when in an exhausted state, cold food or drink makes an immediate drain upon the system for heat before it can supply material for producing combustion, and the body is thereby taxed to supply heat at a time when it is least fitted for it. It is natural, therefore, that there should be a craving for warm food, and as liquid food is deficient in heat-giving matter, the use of cold drink is more injurious than that of cold food. From other experiments it appears that the introduction into the stomach of three or four grains of theine, which is the quantity contained in the third of an ounce of good tea, has the remarkable effect of diminishing the daily waste or disintegration of the bodily tissues which may be measured by the quantity of solid constituents contained in the many secretions, and if such waste be lessened the necessity for food to repair that waste will obviously be decreased in corresponding proportions. In other words, says Professor Johnstone, “by the consumption of a certain quantity of tea daily the health and strength of the body will be maintained to an equal degree upon a smaller supply of ordinary food.” Tea, therefore, saves food; stands to a certain extent in place of food, while at the same time it soothes the body and enlivens the mind. While tea, according to Dr. Sigmond, “has in most instances been substituted for spirituous liquors, and the consequence has been a general improvement in the health and morals of the people, the time, strength, and vigor of the human body being increased by its use. It imparts greater capability of enduring fatigue, and renders the mind more susceptible of the innocent and intellectual pleasures of life, as well as of acquiring useful knowledge more readily, being not only a stimulant to the mental faculties but also the most beneficial drink to those engaged in any laborious or fatiguing work.” Dr. Jackson testifying “that a breakfast of tea and bread alone is much more strengthening than one of beefsteak and porter.”
In his admirable work on hygiene Dr. Parker remarks that “tea possesses a decidedly stimulating and restorative action on the human system, no depression whatever following its use, the pulse being a little quickened, and the amount of pulmonary carbonic acid accordingly increased.” From this experiment he regards “tea as a most useful article of diet for soldiers, the hot infusion being potent against heat and cold, and more useful still in great fatigue in tropical countries by its great purifying effect on brackish and stagnant water.” Adding that “tea is so light, easily carried and so readily prepared, that it should form the drink, par excellence, of the soldier in service or on the march, above all its power of lessening the susceptibility to malarial and other influences.” And Admiral Inglefield is quoted as strongly recommending the use of tea to Arctic travelers and explorers, as seamen who surveyed with him in the polar regions after an experience of one day’s rum drinking came to the conclusion that tea was more beneficial to them while undergoing the severe work and intense cold. Under the infirmities of advancing age, especially when the digestive powers become enfeebled and the size and weight of the body begin perceptibly to diminish, the value of tea in checking the rapid waste of tissue is particularly observable, and persons, when very much fatigued, will be sooner refreshed by drinking a cup of moderately strong, good tea, than by drinking wine or spirits of any kind. In allaying or satisfying severe thirst, no beverage will be found as efficacious as a draught of cold tea.
Lettson furnishes a calculation, partly his own and partly from other sources, in which he endeavors to prove how much is, in his view, unnecessarily expended by the poor for tea. But the observations of Liebig, if correct, and in all probability they are, offer a satisfactory explanation of the cause of the partiality of the poorer classes, not alone for tea, but for tea of an expensive and therefore superior quality. “We shall never certainly,” he says, “be able to discover how people were led to the use of hot infusions of the leaves of a certain shrub (tea) or a decoction of certain roasted seeds (coffee); some cause there must be which would explain how the practice has become a necessary of life to whole nations.” But it is still more remarkable that the beneficial effects of both plants on the health must be ascribed to one and the same substance, the presence of which in two vegetables belonging to natural families, the product of different quarters of the globe, could hardly have presented itself to the boldest imagination, recent research having shown in such a manner as to exclude all doubt that the caffeine of coffee and the theine of tea are in all respects identical. And without entering into the medical action of this principle, it will surely appear a most startling fact, even if we deny its influence on the process of secretion, that this substance, with the addition of oxygen and the elements of water, can yield taurine, the nitrogenous compound peculiar to bile. So that if an infusion of tea contain no more than 1-10 of a grain of theine, and contributes, as has been shown, to the formation of bile, the action, even of a such a small quantity, cannot be looked upon as a nullity. Neither can it be deemed that in the case of non-atomized food or a deficiency of the exercise required to cause a change of matter in the tissues, and thus to yield the nitrogenized product which enters into the composition of bile, the health may be benefited by the use of compounds essential to the production of this important element of respiration. In a chemical sense, and it is this sense alone that theine is in virtue of its composition better adapted to this purpose than all other nitrogenized vegetable principles yet discovered. To better prove how the action of tea may be explained, we must call to mind that the chief constituents of the bile contain only 3.8 per cent. of nitrogen, of which only one-half belongs to the taurine. Bile contains in its natural state water and solid matter in the proportion of 90 parts of the former to 10 parts of the latter, and if, we suppose, these 10 parts of solid matter to be cholenic acid with 5.87 per cent. of nitrogen, then 100 parts of bile must contain 0.171 of nitrogen in the form of taurine, which quantity is contained in .06 parts of theine, or, in other words, 272 grains of theine can give to an ounce of bile the quantity of nitrogen it contains in the form of taurine. The action of the compound in ordinary circumstances is not obvious, but that it unquestionably exists and exerts itself in both tea and coffee is proven by the fact that both were originally met with among nations whose diet was chiefly vegetable. These facts clearly show in what manner tea proves to the poor a substitute for animal food, and why it is that females, literary persons and others of sedentary habits or occupation, who take but little exercise, manifest such a partiality for tea, and also explain why the numerous attempts made to substitute other articles in its place have so signally failed.