TEA, Medical Properties of. The botany of tea is given under TETRA, in the NATURAL HISTORY DIVISION of this work ; its chemical properties are noticed under CAFEEINE ; for an account of its culture see TEA AND ?us TEA TRADE.
Before attempting to estimate the action of tea on the human system, it is necessary to call to mind that some of the offects are due to the plants mixed with the real tea, several of which, such as the Moroni/las ineonspicaus, are stimolants of the highest order ; and in other instances deleterious chemical compounds arc used by the Chinese to convert damaged black teas into saleable green teas. (Davis, ' Chinese,' ii. 406.) For the effects of these, tea is not justly chargeable. A correct estimate of the action of tea is not easily formed; yet the most dispassionate inquirers regard it as a narcotic, the stimulating period of which is the most conspicuous and of longest duration. Tea has been preposterously praised by some writers, and unjustly accused by others as being productive of numerous diseases : above all it has been charged with causing an increase of nervous diseases It would perhaps be more just to attribute the increase of such complaints to the more complicated state of our social relations, arising from an augmented population, and an advance in luxury, with the more frequent infringement of the natural laws, particularly turning night into day, and not seldom day into night, as is tbe practice of the votaries of fashion. That tea should not suit all constitutions or all ages is not remarkable. It is less suited for young children than for adults ; indeed for very young children it is extremely improper, pro ducing, like all narcotics, a morbid state of the brain and nervous system. It is also unsuited for those of an irritable nature, and like wise for those of a lencophlegmatic constitution. Such persons can ill bear much liquid of any kind, particularly in the evening, and prosper best on a very dry diet, to which growing children of this constitution should be strictly confined. [DILtiY.Yrs.] It may not be true that the use of tea, as alleged by Dr. Lettsom, has been the main cause of the increase of scrofulous diseases, still as diseases of this class are the only diseases which are proved by the reports of the registrar-general to be stationary, or perhaps more frequent than others, whatever impairs the nervous power and ultimately the digestive function in strumous children should be avoided. His advice is sound where he
says," It ought by no means to be the common diet of boarding schools ; if it be allowed sometimes as a treat, they should be at the same time informed that the constant use of it would be injurious to their health, strength, and constitution." Those to whom it is most suited are the plethoric and sanguine. Upon the same principle it is a proper article of diet and perhaps the best common drink at the beginning of fevers and inflammatory complaints. In a peculiar state of brain, termed by Mr. Newnham (`Observations on Medical and Dietetical Properties of Green Tea ') sthenic excitement, a state clearly bordering on inflammation, especially if produced by alcoholic stimu lants, or by intense and long-continued application of mind to any par ticular object of literary research, green tea acts as a salutary remedy. On the contrary, in states of diminished excitement, morbid vigilance and nervous disturbance follow its use. It is not an uncommon practice with ardent students, when pushing their studies far into the night, to resist the claims of nature for repose, and keep themselves awake by the frequent use of tea. That it answers the purpose at the time cannot be denied, but the object is often attained at a fearful price, the destruction of health and vigour both of mind and body being the penalty. But more effect is produced by small doses, frequently repeated, than by large ones. See the paper on the Uses of Tea in the healthy System,' read before the Society of Arts, 15th February, 1S61, p. 186. Dr. Smith's remarks are based upon a most extensive series of experiments—the results of which are most important. Less injury results in these cases from the use of coffee. There is this difference between the morbid states of the nervous system produced by coffee and those resulting from tea : that the former generally subside or disappear entirely on relinquishing its use; those from the latter are more permanent, and often incapable of being eradicated. Nevertheless many persona have immediately found their health improved by entirely relinquishing the use of tea, or even omitting it only at breakfast, for which meal it is certainly less proper than for the evening beverage. 1 hose for whom tea is unsuited will generally find weak cocoa the most proper substitute.