All about coffee by William H. Ukers
13. General health and conditions of
816 words | Chapter 104
administration
Subsequent to these investigations was that of Hollingworth[312] which
is at once the most comprehensive, carefully conducted, and
scientifically accurate one yet performed. He employed an ample number
of subjects in his experimentation; and both his subjects, and the
assistants who recorded the observations, were in no wise cognizant of
the character or quantity of the dose of caffein administered, the other
experimental conditions being similarly rigorous and extensive.
The purpose of his study was to determine both qualitatively and
quantitatively the effect of caffein on a wide range of mental and motor
processes, by studying the performance of a considerable number of
individuals for a long period of time, under controlled conditions; to
study the way in which this influence is modified by such factors as the
age, sex, weight, idiosyncrasy, and previous caffein habits of the
subjects, and the degree to which it depends on the amount of the dose
and the time and conditions of its administration; and to investigate
the influence of caffein on the general health, quality and amount of
sleep, and food habits of the individual tested.
To obtain this information the chief tests employed were the steadiness,
tapping, coordination, typewriting, color-naming, calculations,
opposites, cancellation, and discrimination tests, the familiar
size-weight illusion, quality and amount of sleep, and general health
and feeling of well-being. A brief review of the results of these tests
is given in the tabular summary.
From these Hollingworth concluded that caffein influenced all the tests
in a given group in much the same way. The effect on motor processes
comes quickly and is transient, while the effect on higher mental
processes comes more slowly and is more persistent. Whether this result
is due to quicker reaction on the part of motor-nerve centers, or
whether it is due to a direct peripheral effect on the muscle tissue is
uncertain, but the indications are that caffein has a direct action on
the muscle tissue, and that this effect is fairly rapid in appearance.
The two principal factors which seem to modify the degree of caffein
influence are _body weight_ and _presence of food_ in the stomach at the
time of ingestion of the caffein. In practically all of the tests the
magnitude of the caffein influence varied inversely with the body
weight, and was most marked when taken on an empty stomach or without
food substance. This variance in action was also true for both the
quality and amount of sleep, and seemed to be accentuated when taken on
successive days; but it did not appear to depend on the age, sex, or
previous caffein habits of the individual. Those who had given up the
use of caffein-containing beverages during the experiment did not report
any craving for the drinks as such, but several expressed a feeling of
annoyance at not having some sort of a warm drink for breakfast.
It is interesting to note that he also found a complete absence of any
trace of secondary depression or of any sort of secondary reaction
consequent upon the stimulation which was so strikingly present in many
of the tests. The production of an increased capacity for work was
clearly demonstrated, the same being a genuine drug effect, and not
merely the effect of excitement, interest, sensory stimulation,
expectation, or suggestion. However, this study does not show whether
this increased capacity comes from a new supply of energy introduced or
rendered available by the drug action, or whether energy already
available comes to be employed more effectively, or whether fatigue
sensations are weakened and the individual's standard of performance
thereby raised. But they do show that from a standpoint of mental and
productive physical efficiency "the widespread consumption of caffeinic
beverages, even under circumstances in which and by individuals for whom
the use of other drugs is stringently prohibited or decried, is
justified."
_Conclusion_
Brief summarization of the information available on the pharmacology of
coffee indicates that it should be used in moderation, particularly by
children, the permissible quantity varying with the individual and
ascertainable only through personal observation. Used in moderation, it
will prove a valuable stimulant increasing personal efficiency in mental
and physical labor. Its action in the alimentary régime is that of an
adjuvant food, aiding digestion, favoring increased flow of the
digestive juices, promoting intestinal peristalsis, and not tanning any
portion of the digestive organs. It reacts on the kidneys as a diuretic,
and increases the excretion of uric acid, which, however, is not to be
taken as evidence that it is harmful in gout. Coffee has been indicated
as a specific for various diseases, its functions therein being the
raising and sustaining of low vitalities. Its effect upon longevity is
virtually _nil_. A small proportion of humans who are very nervous may
find coffee undesirable; but sensible consumption of coffee by the
average, normal, non-neurasthenic person will not prove harmful but
beneficial.
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