CHAPTER XVIII

PHARMACOLOGY OF THE COFFEE DRINK _General physiological action--Effect on children--Effect on longevity--Behavior in the alimentary régime--Place in dietary--Action on bacteria--Use in medicine--Physiological action of "caffetannic acid"--Of caffeol--Of caffein--Effect of caffein on mental and motor efficiency--Conclusions_ By Charles W. Trigg Industrial Fellow of the Mellon Institute of Industrial Research, Pittsburgh, 1916-1920 The published information regarding the effects of coffee drinking on the human system is so contradictory in its nature that it is hazardous to make many generalizations about the physiological behavior of coffee. Most of the investigations that have been conducted to date have been characterized by incompleteness and a failure to be sufficiently comprehensive to eliminate the element of individual idiosyncrasy from the results obtained. Accordingly, it is possible to select statements from literature to the effect either that coffee is an "elixir of life," or even a poison. This is a deplorable state of affairs, not calculated to promote the dissemination of accurate knowledge among the consuming public, but it may be partly excused upon the grounds that experimental apparatus has not always been at the level of perfection that it now occupies. Also, to do justice to some of the able men who have interested themselves in this problem, it should be said that some of their results were obtained in researches, distinguished by painstaking accuracy, which have effected the establishment of the major reactions of ingested coffee. _The Physiological Action of Coffee_ Drinking of coffee by mankind may be attributed to three causes: the demand for, and the pleasing effects of, a hot drink (a very small percentage of the coffee consumed is taken cold), the pleasing reaction which its flavors excite on the gustatory nerve, and the stimulating effect which it has upon the body. The flavor is due largely to the volatile aromatic constituents, "caffeol," which, when isolated, have a general depressant action on the system; and the stimulation is caused by the caffein. The general and specific actions of these individual components, together with that of the hypothetical "caffetannic acid," are considered under separate headings. Coffee may be considered a member of the general class of adjuvant, or auxiliary, foods to which other beverages and condiments of negligible inherent food value belong. Its position on the average menu may be attributed largely to its palatability and comforting effects. However, the medicinal value of coffee in the dietary and _per se_ must not be overlooked. The ingestion of coffee infusion is always followed by evidences of stimulation. It acts upon the nervous system as a powerful cerebro-spinal stimulant, increasing mental activity and quickening the power of perception, thus making the thoughts more precise and clear, and intellectual work easier without any evident subsequent depression. The muscles are caused to contract more vigorously, increasing their working power without there being any secondary reaction leading to a diminished capacity for work. Its action upon the circulation is somewhat antagonistic; for while it tends to increase the rate of the heart by acting directly on the heart muscle, it tends to decrease it by stimulating the inhibitory center in the medulla.[188] The effect on the kidneys is more marked, the diuretic effect being shown by an increase in water, soluble solids, and of uric acid directly attributable to the caffein content of the coffee taken. In the alimentary tract coffee seems to stimulate the oxyntic cells and slightly to increase the secretion of hydrochloric acid, as well as to favor intestinal peristalsis. It is difficult to accept reports of coffee accomplishing both a decrease in metabolism and an increase in body heat; but if the production of heat by the demethylation of caffein to form uric acid and a possible repression of perspiration by coffee be considered, the simultaneous occurrence of these two physiological reactions may be credited. The disagreement of medical authorities over the physiological effects of coffee is quite pronounced. This may be observed by a careful perusal of the following statements made by these men. It will be noticed that the majority opinion is that coffee in moderation is not harmful. Just how much coffee a person may drink, and still remain within the limits of moderation and temperance, is dependent solely upon the individual constitution, and should be decided from personal experience rather than by accepting an arbitrary standard set by some one who professes to be an authority on the matter. A writer in the _British Homeopathic Review_[189] says that "the exciting effects of coffee upon the nervous system exhibit themselves in all its departments as a temporary exaltation. The emotions are raised in pitch, the fancies are lively and vivid, benevolence is excited, the religious sense is stimulated, there is great loquacity.... The intellectual powers are stimulated, both memory and judgment are rendered more keen and unusual vivacity of verbal expression rules for a short time." He continues: Hahnemann gives a characteristically careful account of the coffee headache. If the quantity of coffee taken be immoderately great and the body be very excitable and quite unused to coffee, there occurs a semilateral headache from the upper part of the parietal bone to the base of the brain. The cerebral membranes of this side also seem to be painfully sensitive, the hands and feet becoming cold, and sweat appears on the brows and palms. The disposition becomes irritable and intolerant, anxiety, trembling and restlessness are apparent.... I have met with headaches of this type which yielded readily to coffee and with many more in which the indicated remedy failed to act until the use of coffee as a beverage was abandoned. The eyes and ears suffer alike from the super-excitation of coffee. There is a characteristic toothache associated with coffee. In apparent contradiction of this opinion, Dr. Valentin Nalpasse,[190] of the Faculty of Medicine of Paris, states: When coffee is properly made and taken in moderation, it is a most valuable drink. It facilitates the digestion because it produces a local excitement. Its principal action gives clear and stable imaginative power to the brain. By doing that, it makes intellectual work easy, and, to a certain extent, regulates the functions of the brain. The thoughts become more precise and clear, and mental combinations are formed with much greater rapidity. Under the influence of coffee, the memory is sometimes surprisingly active, and ideas and words flow with ease and elegance.... Many people abuse coffee without feeling any bad effect. Discussing the use and abuse of coffee, I.N. Love[191] says: The world has in the infusion of coffee one of its most valuable beverages. It is a prompt diffusible stimulant, antiseptic and encourager of elimination. In season it supports, tides over danger, helps the appropriate powers of the system, whips up the flagging energies, enhances the endurance; but it is in no sense a food, and for this reason it should be used temperately. Also Dr. Jonathan Hutchinson[192] makes the following weighty pronouncement: In reference to my suggestion to give children tea and coffee. I may explain that it is done advisedly. There is probably no objection to their use even at early ages. They arouse the dull, calm the excitable, prevent headaches, and fit the brain for work. They preserve the teeth, keep them tight in their place, strengthen the vocal chords, and prevent sore throat. To stigmatize these invaluable articles of diet as "nerve stimulants" is an erroneous expression, for they undoubtedly have a right to rank as nerve nutrients. But Dr. Harvey Wiley[193] comes forth with evidence on the other side, saying: The effects of the excessive use of coffee, tea, and other natural caffein beverages is well known. Although the caffein is combined in these beverages naturally, and they are as a rule taken at meal times, which mitigates the effects of the caffein, they are recognized by every one as tending to produce sleeplessness, and often indigestion, stomach disorders, and a condition which, for lack of a better term, is described as nervousness.... The excessive drinking of tea and coffee is acknowledged to be injurious by practically all specialists. Dr. V.C. Vaughn,[194] of the University of Michigan, speaking of tea and coffee, expresses this opinion: I believe that caffein used as a beverage and in moderation not only is harmless to the majority of adults, but is beneficial. This verdict is upheld by the results of a symposium[195] conducted by the _Medical Times_, in which a large majority of the medical experts participating, among whom may be enumerated Drs. Lockwood, Wood, Hollingworth, Robinson, and Barnes, agreed that the drinking of coffee is not harmful _per se_, but that over-indulgence is the real cause of any ill effects. This is also true of any ingested material. Insomnia is a condition frequently attributed to coffee, but that the authorities disagree on this ground is shown by Wiley's[196] contention, "We know beyond doubt that the caffein (in coffee) makes a direct attack on the nerves and causes insomnia." While Woods Hutchinson[197] observes: Oddly enough, a cup of hot, weak tea or coffee, with plenty of cream and sugar, will often help you to sleep, for the grateful warmth and stimulus to the lining of the stomach, drawing the blood into it and away from the head, will produce more soothing effects than the small amount of caffein will produce stimulating and wakeful ones. The writer has often had people remark to him that while black coffee sometimes kept them awake, coffee with cream or sugar or both made them drowsy. In the course of experiments conducted by Montuori and Pollitzer[198] it was found that coffee prepared by hot infusion when given by mouth or hypodermically with the addition of a small dose of alcohol proved an efficient means of combating the pernicious effects of low temperatures. Coffee prepared by boiling, and tea, showed negative effects. The value of coffee as a strength-conserver, and its function of increasing endurance, morale, and healthfulness, was demonstrated by the great stress which the military authorities, in the late and in previous wars, placed upon furnishing the soldiers with plenty of good coffee, particularly at times when they were under the greatest strain. Various articles[199] record this fact; and these statements are further borne out by the data given below in the discussion of the physiological effects of caffein, to which the majority of the stimulating effects of coffee may be attributed. According to Fauvel,[200] with a healthy patient on a vegetable diet, chocolate and coffee increase the excretion of purins, diminishing the excretion of uric acid and apparently hindering the precipitation of uric acid in the organism. This diminution, however, was not due to retention of uric acid in the organism. "Habit-forming" is one of the adjectives often used in describing coffee, but it is a fact that coffee is much less likely than alcoholic liquors to cause ill effects. A man rarely becomes a slave of coffee; and excessive drinking of this beverage never produces a state of moral irresponsibility or leads to the commission of crime. Dr. J.W. Mallet,[201] in testimony given before a Federal Court, stated that caffein and coffee were not habit-forming in the correct sense of the term. His definition of the expression is that the habit formed must be a detrimental and injurious one--one which becomes so firmly fixed upon a person forming it that it is thrown off with great difficulty and with considerable suffering, continuous exercise of the habit increasing the demand for the habit-forming drug. It is well known that the desire ceases in a very short period of time after cessation of use of caffein-containing beverages, so that in that sense, coffee is not habit-forming. [Illustration: MEN AND WOMEN LABORERS PICKING COFFEE ON A SÃO PAULO ESTATE] [Illustration: SACKING COFFEE IN A WAREHOUSE AT THE PORT OF SANTOS] [Illustration: PICKING AND SACKING COFFEE IN BRAZIL] It has been shown by Gourewitsch[202] that the daily administration of coffee produces a certain degree of tolerance, and that the doses must be increased to obtain toxic results. Harkness[203] has been quoted as stating that "taken in moderation; coffee is one of the most wholesome beverages known. It assists digestion, exhilarates the spirits, and counteracts the tendency to sleep." Carl V. Voit,[204] the German physiological chemist, says this about coffee: The effect of coffee is that we are bothered less by unpleasant experiences and become more able to conquer difficulties; therefore, for the feasting rich, it makes intestinal work after a meal less evident and drives away the deadly ennui; for the student it is a means to keep wide awake and fresh; for the worker it makes the day's fatigue more bearable. Dr. Brady[205] believes that the so-called harmfulness of coffee is mainly psychological, as evidenced by his expression, "Most of the prejudice which exists against coffee as a beverage is based upon nothing more than morbid fancy. People of dyspeptic or neurotic temperament are fond of assuming that coffee must be bad because it is so good, and accordingly, denying themselves the pleasure of drinking it." The recounting of evidence, both _pro_ and _con_, relevant to the general effects of coffee could continue almost _ad infinitum_, but the fairest unification of the various opinions is best quoted from Woods Hutchinson[206]: Somewhere from 1 to 3 percent of the community are distinctly injured or poisoned by tea or coffee, even small amounts producing burning of the stomach, palpitation of the heart, headache, eruptions of the skin, sensations of extreme nervousness, and so on; though the remaining 97 percent are not injured by them in any appreciable way if consumed in moderation. So, if one is personally satisfied that he belongs to the abnormal minority, and has not been argued by fallacious reasoning into his belief that coffee injures him, he should either reduce his consumption of coffee or let it alone. Even those most vitally interested in the commercial side of coffee will admit that this is the logical procedure. _Effects of Coffee on Children_ The same sort of controversy has raged around the question of the advisability of giving coffee to children as has occurred regarding its general action. Dr. J. Hutchinson[207] advocates furnishing children with coffee, while Dr. Charlotte Abbey[208] is strongly against such a practise, claiming that use of caffein-containing beverages before the attainment of full growth will weaken nerve power. Nalpasse[209] observes that until fully developed the young are immoderately excited by coffee; and Hawk[210] is of the opinion that to give such a stimulant to an active school-child is both logically and dietetically incorrect. Dr. Vaughn[211] advances this scientific argument against the drinking of coffee by children under seven years of age: In proportion to body weight the young contain more of the xanthin bases than adults. They are already laden with these physiological stimulants, and the additional dose given in tea or coffee may be harmful. In a study of the effects of coffee drinking upon 464 school children, C.K. Taylor[212] found a slight difference in mental ability and behavior, unfavorable to coffee. About 29 percent of these children drank no coffee; 46 percent drank a cup a day; 12 percent, 2 cups; 8 percent, 3 cups; and the remainder, 4 or more cups a day. The measurements of height, weight, and hand strength also showed a slight advantage in favor of the non-coffee drinkers. If these results be taken as truly representative, their indication is obvious. However, it seems desirable to repeat these experiments upon other groups; at the same time noting carefully the factors of environment, and other diet, before any criterion is made. As a refutation to this experimental evidence is the practical experience of the inhabitants of the Island of Groix, off the Brittany coast, whose annual consumption of coffee is nearly 30 pounds per capita, being ingested both as the roasted bean and as an infusion. It is reported that many of the children are nourished almost entirely on coffee soup up to ten years of age, yet the mentality and physique of the populace does not fall below that of others of the same stock and educational opportunities.[213] Pertinent in this connection is Hawk's[214] statement that young mothers should refrain from the use of coffee, as caffein stimulates the action of the kidneys and tends to bring about a loss from the body of some of the salts necessary to the development of the unborn child as well as for the proper production of milk during the nursing period. The caffein of coffee also increases the flow of milk, but the milk produced is correspondingly dilute and a later decreased secretion may be expected. Furthermore, some of the caffein of the coffee may pass into the mother's milk, thus reaching the child, so that the use of coffee during the nursing period is undesirable on this ground also. Naturally, the question arises as to whether this arraignment is purely theoretical or based upon analytical and clinical data. It is a difficult matter definitely to set an age below which coffee should not be drunk, as the time of reaching maturity varies with climate and ancestral origin. Yet, from a theoretical standpoint, children before or during the adolescent period should be limited to the use of a rather small amount of tea and coffee as beverages, as their poise and nerve control have not reached a stage of development sufficient to warrant the stimulation incident to the consumption of an appreciable quantity of caffein. _Coffee Drinking and Longevity_ There are many who would have us believe that the use of coffee is only a means toward the end of quickly reaching the great beyond; but it is known that the habitual coffee drinker generally enjoys good health, and some of the longest-lived people have used it from their earliest youth without any apparent injury to their health. Nearly every one has an acquaintance who has lived to a ripe old age despite the use of coffee. Quoting Metchnikoff[215]: In some cases centenarians have been much addicted to the drinking of coffee. The reader will recall Voltaire's reply when his doctor described the grave harm that comes from the abuse of coffee, which acts as a real poison. "Well", said Voltaire, "I have been poisoning myself for nearly eighty years." There are centenarians who have lived longer than Voltaire and have drunk still more coffee. Elizabeth Durieux, a native of Savoy, reached the age of