In many people the use of the above stimulants produces greater energy, especially for mental work, and the process of thought may be facilitated by their means, although we are not prepared to approve them as a general rule. At any rate if such properties are to be found in these stimulants, they are available only in small amounts and not exceeding a given limit, for in excess the same rule applies to them as to alcohol.
There are, indeed, certain authorities who condemn them, and go so far even as to call them poisonous. But it is a leading principle of this work to condemn exaggeration and fanaticism in any form, and always to observe the means that are best for all rules of life. Sobriety and impartiality in everything must be the guiding stars for such a work as this. We must not forget that the millions of human beings that are on the earth have each a different kind of constitution, and many of them practically cannot exist without the assistance of certain stimulants, without which life would be a burden to them; and as it does no good to make prohibitions which cannot be kept, even though made with the best of intentions, all we can do is to endeavor to control certain things and to see that some limit is set for their use.
There are two varieties of tea, both of which, however, are gathered from the same plant; their only difference lies in their method of preparation; their differentiation is in color—black and green. The former undergoes a process of fermentation and is then dried slowly over charcoal fires, while green tea derives its color from having been dried in a fresh condition over a wood fire.
When we want to make good tea we must take finely washed leaves and make an infusion, so that the greatest possible surface of the leaves shall come in contact with the boiling water; and it is best to let this contact be only for a short time, as otherwise the tea will be too strong and less beneficial to health.
The most important elements in tea are thein, a substance that is identically similar to caffein in coffee, ethereal oils, tannin, and extractives. Green tea contains more thein and ethereal oils, and also more tannic acid, than black tea; and the longer it is in contact with boiling water the greater will be the quantity of tannic acid derived from it. According to R. Hutchison,[320] the ashes of tea contain a large percentage of manganates (1.09 per cent. manganese hydroxide) and much iron (4.47 per cent. oxide of iron).
After taking a cup of tea there is a feeling of great comfort; we feel lighter and less fatigued, which is due, as discovered by Koch and Kraepelin,[321] to the combined action of the ethereal oils and of the thein. The tannic acid contained in tea may also give good results in the treatment of certain diarrhœas. The actions of tea are very similar to those of coffee, which is only natural, since both contain the same chemical agent, thein or caffein. Still, though chemically the same, physiologically doubtless there are some slight differences. Although both promote endurance in physical and mental work, according to some views, still in many people nervous irritability, such as sleeplessness, is greater from tea than from coffee. Coffee is a better diuretic than tea, and it has been found that common salt is eliminated in the larger quantity after taking coffee. For weak stomachs neither is advisable.
In many cases tea is less easily assimilated than coffee, on account of digestive disturbance caused by its tannin contents; while to many others tea proves more suitable than coffee. When these beverages are taken in large quantities there are very serious symptoms of nervous disorders, such as great excitability, sleeplessness, palpitation of the heart, trembling, etc. Indeed, sometimes the very serious condition of actual intoxication is brought about.
It is quite amazing what large quantities of tea are consumed in certain countries—in England, for example; and in many instances the moderate use of good wine would certainly create less mischief than the immoderate use of tea. Tea is not so beneficial to the kidneys as coffee, and as we have mentioned in the chapter on the hygiene of the kidneys, irritation of the kidney tissues may be at times observed after the use of tea. As in the case of alcohol, moderation with tea and coffee is necessary. According to the researches of Böttger even weak infusions of tea and coffee are harmful to children, and strong infusions to grown up people.
The most important substance in coffee is caffein, a product already mentioned as being chemically identical with thein. When we take a cup of coffee about 0.1 gramme of caffein enters the system, and also 0.2 gramme of tannic acid, as shown by Robert Hutchison. When coffee is roasted aromatic oils arise, which give coffee its delicious aroma. Coffee acts as a stimulant to the heart and also to muscular contractions. Its beneficial action on the kidneys has been referred to. When coffee is taken it is more hygienic to take it not too strong, and invariably with cream or milk.
According to Emil Fisher, caffein is a thrice methylated xanthin, from which it can be produced artificially. As caffein, or thein, contains purin bodies, they also augment the amount of uric acid in the body, and especially so when they are taken in large quantities. Because coffee, tea, or cocoa give rise to uric acid, Haig would like to banish them entirely from the diet. We do not feel inclined to follow Haig in such a fanatical view, for after all it is nearly impossible to so live that we should not introduce some small amount of uric acid into the system; we are always producing a certain amount of it in the system, as already mentioned, and whether a trifle more or less be taken can make no difference, as minute quantities of uric acid cannot play an important rôle if our kidneys are in good condition to eliminate them. With a large amount of meat we eliminate two grams of uric acid in every twenty-four hours, and even with an entirely vegetarian diet the urine still contains 0.2 to 0.7 gramme, according to Bunge. Should we be so unreasonable as to refuse a person a cup of weak tea or coffee, after their having been accustomed to such for a lifetime, merely to avoid a few more atoms of uric acid. Especially should we refuse them a weak cup of coffee, remembering that such is a good diuretic and assists in the elimination of baneful products through the kidneys? Only to actually gouty people might such a veto, perhaps, be reasonably applied.
Cocoa is a very valuable article of food, and at the same time a very mild stimulant. As its active principle it contains theobromin, which is a twice methylated xanthin. In its chemical and physiological actions theobromin is very similar to caffein. It is, however, in some respects superior to caffein. Thus it can assist muscular activity, according to some authorities, to a higher degree than caffein or thein.
Cocoa has the further advantage of being more digestible than coffee or tea; and as a foodstuff it shows a great superiority over both the latter, as it contains 12 per cent. of albumin, 13 per cent. of carbohydrates, and contains fat—indeed, about 50 per cent.—in a fresh condition.
Cocoa presents fewer drawbacks than tea or coffee; it is less exciting to the nervous system, more digestible, and much more nutritious also. We think, therefore, it is clearly indicated as the best of all stimulants, and, for reasons already stated, we are not afraid to recommend it, in spite of the fact that it may nominally increase the amount of uric acid. Cocoa was also the favorite beverage of the great botanist Linné.
Chocolate is composed of cocoa and a large quantity of sugar, and is quite a pleasant sugar food, which doubtless can be used with profit as a dessert to a lacto-vegetarian diet. It is also suitable for the use of tourists and sporting men in order to enable them the better to endure great fatigue. We often recommend its use in its best quality and in small quantities to those people from whose diet meat is excluded.
Tobacco is a plant, the leaves of which, when prepared by a special process and smoked in the shape of cigars, or in pipes, are able to produce in many people a feeling of exhilaration; and many such smokers are able to do more work, especially brain work, with the aid of a good cigar. Tobacco contains, in addition to noxious salts, a poisonous alkaloid, nicotine, which produces in small amounts in those not accustomed to it, and in all people if in larger quantity, a condition of intoxication. When nicotine is taken for many years, and sometimes even in a shorter time, either by smoking or chewing, very injurious consequences from nicotine poisoning may ensue. According to König, cigarettes are the most dangerous in this respect. It is quite a mistake to think that no nicotine is introduced into the system through smoking; and in chewing mixtures the presence of foreign matters must not be overlooked. Nicotine may exercise a fatal action on various organs—for instance, on the inner parts of the eye and the optic nerve, and the nervous system; but without doubt its most injurious action is on the heart and the stomach. At first it may cause only an irregular pulse and an occasional feeling of a stopping of the heart; but if continued, in spite of these symptoms, for a long time, it can undoubtedly produce the condition of atheromatosis, and will assist in the development of arteriosclerosis, which is probably caused by the action of this substance on the adrenals; for it has been noted by many leading authorities—e.g., Prof. Isaac Adler, of New York—that tobacco produces effects similar to adrenalin.
According to Sir Lauder Brunton[322] and others, tobacco raises the blood-pressure, sometimes enormously. As Brunton says: “I do not know that there is anything that causes such a tremendous contraction of the vessels and raises blood-pressure to such an enormous extent as does nicotine, except, perhaps, the extract of suprarenal capsules, which has an action almost identical with nicotine.”
It has also been shown by Esser[323] that chronic nicotine poisoning is able to produce in animals a great disturbance of the heart and histological alterations of the vagus fibers, and that if nicotine is injected into the circulation it excites the vagus and slows the action of the heart.
Clinically we have observed the great frequency of arteriosclerosis in great smokers, but we do not think that two or three light cigars a day, but never before meals, can do any harm, save in exceptional cases. Indeed, there are a few instances of persons living to be over 100, notwithstanding the fact that they were smokers—a fact contrary to the observations of Hufeland, who pretends that he never heard of such a case. The famous English painter, Mr. Frithe, who died in October, 1909, used to smoke six cigars a day; and Mr. F——, of Chartres, in France, passed last year his 100th birthday in spite of his having taken snuff all his life.