The purposes of food are to promote growth, to supply force and heat, and to
furnish material to repair the waste which is constantly taking place in the
body. Every breath, every thought, every motion, wears out some portion of the
delicate and wonderful house in which we live. Various vital processes remove
these worn and useless particles; and to keep the body in health, their loss
must be made good by constantly renewed supplies of material properly adapted to
replenish the worn and impaired tissues. This renovating material must be
supplied through the medium of food and drink, and the best food is that by
which the desired end may be most readily and perfectly attained. The great
diversity in character of the several tissues of the body, makes it necessary
that food should contain a variety of elements, in order that each part may be
properly nourished and replenished. The food elements. ------------------- The
various elements found in food are the following: Starch, sugar, fats, albumen,
mineral substances, indigestible substances. The digestible food elements are
often grouped, according to their chemical composition, into three classes;
vis., carbonaceous, nitrogenous, and inorganic. The carbonaceous class includes
starch, sugar, and fats; the nitrogenous, all albuminous elements; and the
inorganic comprises the mineral elements. Starch is only found in vegetable
foods; all grains, most vegetables, and some fruits, contain starch in
abundance. Several kinds of sugar are made in nature's laboratory; cane, grape,
fruit, and milk sugar. The first is obtained from the sugar-cane, the sap of
maple trees, and from the beet root. Grape and fruit sugars are found in most
fruits and in honey. Milk sugar is one of the constituents of milk. Glucose, an
artificial sugar resembling grape sugar, is now largely manufactured by
subjecting the starch of corn or potatoes to a chemical process; but it lacks
the sweetness of natural sugars, and is by no means a proper substitute for
them. Albumen is found in its purest, uncombined state in the white of an egg,
which is almost wholly composed of albumen. It exists, combined with other food
elements, in many other foods, both animal and vegetable. It is found abundant
in oatmeal, and to some extent in the other grains, and in the juices of
vegetables. All natural foods contain elements which in many respects resemble
albumen, and are so closely allied to it that for convenience they are usually
classified under the general name of "albumen." The chief of these is gluten,
which is found in wheat, rye, and barley. Casein, found in peas, beans, and
milk, and the fibrin of flesh, are elements of this class. Fats are found in
both animal and vegetable foods. Of animal fats, butter and suet are common
examples. In vegetable form, fat is abundant in nuts, peas, beans, in various of
the grains, and in a few fruits, as the olive. As furnished by nature in nuts,
legumes, grains, fruits, and milk, this element is always found in a state of
fine subdivision, which condition is the one best adapted to its digestion. As
most commonly used, in the form of free fats, as butter, lard, etc., it is not
only difficult of digestion itself, but often interferes with the digestion of
the other food elements which are mixed with it. It was doubtless never intended
that fats should be so modified from their natural condition and separated from
other food elements as to be used as a separate article of food. The same may be
said of the other carbonaceous elements, sugar and starch, neither of which,
when used alone, is capable of sustaining life, although when combined in a
proper and natural manner with other food elements, they perform a most
important part in the nutrition of the body. Most foods contain a percentage of
the mineral elements. Grains and milk furnish these elements in abundance. The
cellulose, or woody tissue, of vegetables, and the bran of wheat, are examples
of indigestible elements, which although they cannot be converted into blood in
tissue, serve an important purpose by giving bulk to the food. With the
exception of gluten, none of the food elements, when used alone, are capable of
supporting life. A true food substance contains some of all the food elements,
the amount of each varying in different foods. Uses of the food elements.
-------------------------- Concerning the purpose which these different
elements serve, it has been demonstrated by the experiments of eminent
physiologists that the carbonaceous elements, which in general comprise the
greater bulk of the food, serve three purposes in the body; 1. They furnish
material for the production of heat; 2. They are a source of force when taken
in connection with other food elements; 3. They replenish the fatty tissues of
the body. Of the carbonaceous elements, starch, sugar, and fats, fats produce
the greatest amount of heat in proportion to quantity; that is, more heat is
developed from a pound of fat than from an equal weight of sugar or starch; but
this apparent advantage is more than counterbalanced by the fact that fats are
much more difficult of digestion than are the other carbonaceous elements, and
if relied upon to furnish adequate material for bodily heat, would be productive
of much mischief in overtaxing and producing disease of the digestive organs.
The fact that nature has made a much more ample provision of starch and sugars
than of fats in man's natural diet, would seem to indicate that they were
intended to be the chief source of carbonaceous food; nevertheless, fats, when
taken in such proportion as nature supplies them, are necessary and important
food elements. The nitrogenous food elements especially nourish the brain,
nerves, muscles, and all the more highly vitalized and active tissues of the
body, and also serve as a stimulus to tissue change. Hence it may be said that a
food deficient in these elements is a particularly poor food. The inorganic
elements, chief of which are the phosphates, in the carbonates of potash, soda,
and lime, aid in furnishing the requisite building material for bones and
nerves. Proper combinations of foods. ----------------------------- While it
is important that our food should contain some of all the various food elements,
experiments upon both animals and human beings show it is necessary that these
elements, especially the nitrogenous and carbonaceous, be used in certain
definite proportions, as the system is only able to appropriate a certain amount
of each; and all excess, especially of nitrogenous elements, is not only
useless, but even injurious, since to rid the system of the surplus imposes an
additional task upon the digestive and excretory organs. The relative proportion
of these elements necessary to constitute a food which perfectly meets the
requirements of the system, is six of carbonaceous to one of nitrogenous.
Scientists have devoted much careful study and experimentation to the
determination of the quantities of each of the food elements required for the
daily nourishment of individuals under the varying conditions of life, and it
has come to be commonly accepted that of the nitrogenous material which should
constitute one sixth of the nutrients taken, about three ounces is all that can
be made use of in twenty-four hours, by a healthy adult of average weight, doing
a moderate amount of work. Many articles of food are, however, deficient in one
or the other of these elements, and need to be supplemented by other articles
containing the deficient element in superabundance, since to employ a dietary in
which any one of the nutritive elements is lacking, although in bulk it may be
all the digestive organs can manage, is really starvation, and will in time
occasion serious results. It is thus apparent that much care should be
exercised in the selection and combination of food materials. Such knowledge is
of first importance in the education of cooks and housekeepers, since to them
falls the selection of the food for the daily needs of the household; and they
should not only understand what foods are best suited to supply these needs, but
how to combine them in accordance with physiological laws. About the Author
John Ugoshowa. For more information about cooking see the cooking section of The
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