When this investigation, the results of which have been detailed in
the foregoing pages was first planned, it was intended to be simply a
physiological study of the minimal proteid requirement of the healthy
man, extended over sufficient time to render the results of scientific
and practical value. There were no special theories involved, no special
system of dietetics in view, but the object was simply to ascertain
experimentally the minimum amount of proteid or albuminous food necessary
for the maintenance of health and strength, under ordinary conditions
of life. The impression in the mind of the writer was that there was
no satisfactory scientific evidence to support the views held by most,
if not all, physiologists regarding the needs of the body for food,
especially nitrogenous or proteid food, and that the dietary standards
universally adopted by scientific men were of very questionable accuracy,
being founded mainly upon the customs and habits of mankind rather than
upon any systematic study of what the actual necessities of the body are.
The results attained have certainly thrown a great deal of light upon
this question of minimal proteid requirement, and the experimental
study has been throughout a purely physiological one, but as the work
has progressed the writer has been more and more impressed with the
importance and significance of the results in their bearing upon the
broader problem of general physiological economy in nutrition. There
is no question, in view of our results, that people ordinarily consume
much more food than there is any real physiological necessity for, and
it is more than probable that this excess of food is in the long run
detrimental to health, weakening rather than strengthening the body, and
defeating the very objects aimed at.
Confining our conclusions to general statements, it may be said that
our results, obtained with a great diversity of subjects, justify
the conviction that the minimal proteid requirement of the healthy
man under ordinary conditions of life is far below the generally
accepted dietary standards, and far below the amounts called for by the
acquired taste of the generality of mankind. Expressed in different
language, the amount of proteid or albuminous food needed daily for the
actual physiological wants of the body is not more than one-half that
ordinarily consumed by the average man. Body-weight (when once adjusted
to the new level), health, strength, mental and physical vigor, and
endurance can be maintained with at least one-half of the proteid food
ordinarily consumed; a kind of physiological economy which, if once
entered upon intelligently, entails no hardship, but brings with it an
actual betterment of the physical condition of the body. It holds out
the promise of greater physical strength, increased endurance, greater
freedom from fatigue, and a condition of well-being that is full of
suggestion for the betterment of health.
Physiological economy in nutrition means temperance, and not prohibition.
It means full freedom of choice in the selection of food. It is not
cereal diet nor vegetarianism, but it is the judicious application of
scientific truth to the art of living, in which man is called upon to
apply to himself that same care and judgment in the protection of his
bodily machinery that he applies to the mechanical products of his skill
and creative power.
Food requirements must of necessity vary with changing conditions, but
with due recognition of this fundamental principle, all the results so
far obtained in this investigation, with a great variety of persons,
point to the conclusion that the real demands of the body for proteid
food do not exceed fifty per cent of the amount generally consumed.
One-half of the 118 grams of proteid food called for daily by the
ordinary dietary standards is quite sufficient to meet all the real
physiological needs of the body, certainly under ordinary conditions of
life; and with most individuals, especially persons not leading an active
out-of-door life, even smaller amounts will suffice. Excess means waste,
but of far greater importance is the unnecessary strain placed upon the
body by this uncalled-for excess of food material, which must be gotten
rid of at the expense of energy that might better be conserved for more
useful purposes.
Further, the _total_ consumption of food by the average individual,
non-nitrogenous as well as nitrogenous, is considerably greater than the
real needs of the body demand, although here we must give closer heed
to the varying requirements of the body incidental to varying degrees
of activity. The man whose work is mainly mental has no real need for
high fuel values in his daily ration. For such a man, a high potential
energy in the daily intake of food is an incubus and not a gain. Body
equilibrium can be maintained on far less than 3000 calories per day by
the brain worker, and in the interest of health, strength, and vigor,
as well as scientific truth, why teach the doctrine that a healthy man
needs, on an average, foodstuffs to furnish 3000 calories or more per
day, with 16 to 18 grams of nitrogen in the form of proteid? Moreover,
as our experiments have clearly indicated, even the man who is called
upon to perform considerable physical work has no apparent need for a
fuel value in his food of 3000 calories per day. No doubt, the man who
works at hard labor for ten or twelve hours a day will require a larger
intake of fats and carbohydrates, sufficient to yield even more than 3000
calories, but this is not true of the moderate worker, nor of the average
man whose work is in large measure mental rather than physical.
Finally, the writer may be permitted to express the hope that the outcome
of this experimental work will serve to arouse scientific and intelligent
interest in a subject which promises fruitful results for the individual,
and for the community.