starches and sugars is an important item for those who wish to call
upon the fats stored within the body for daily heat and energy and
thus reduce in weight. If sufficient starches, sugars, and fats are
not consumed in the food to supply the daily heat and energy released
by exercise, the body calls upon the sugars and starches temporarily
stored up and, when these have been consumed, upon the reserve of
fat. If much fat is consumed in the daily food this fat in the blood
will be oxidized before the fat stored about the muscular tissue. The
scientific reduction of weight, therefore, lies in the regulation of
the supply of starches, sugars, and fats consumed, and, the oxidation
of more of these substances through an increase in the daily exercise.
Deep breathing of pure air should accompany all exercises, to supply
sufficient oxygen for combustion, or oxidation.
Manual laborers require more fat for energy than do people whose habits
are sedentary. School children, or children who play hard, should have
sufficient fat, and where fats are withheld, sugar should be freely
supplied.
The supply of fat stored in the body depends upon the quantity
consumed with the food, upon the quantity used up in heat and energy,
in muscular exercise, or in mental force. The quantity thus consumed
depends somewhat upon the condition of the nerves. If the nerves are
weak, they do not properly direct digestion and assimilation and less
fat is consumed in the digestive and assimilative processes.
=Butter and Cream.= The fat present in milk depends, of course, upon
the quality of the milk. There is as much butter fat in a glass of
fresh Jersey milk as in a glass of cream, which has been separated, by
machinery, from the milk of some other cows. The cream from some Jersey
cows is almost all butter. Skimmed milk contains very little fat. If
milk is drunk by the adult, as a means of storing up more fat within
the body, the cream should be stirred into it.
=The Fat of Meat= should be thoroughly cooked and cooked with moisture.
All meats in the process of baking or frying should be covered, in
order to retain the moisture. To make fat easily digestible it should
be well masticated.
Bacon, if fully immersed in its own grease, in the process of frying,
is a common source of fat and is easily digested.
=Cod Liver Oil= from the liver of the codfish, is more easily absorbed
and assimilated than any other fat. The odor is not pleasant and a
little lemon juice, salt, baking soda, or any substance for pungency
and flavor, may be added to make it palatable. The pure oil taken in
this way is perhaps preferable to the prepared emulsions. One has the
advantage, at least, of knowing what he is taking.
=Olive Oil= is crushed from ripe olives. It is often used where cod
liver oil is prescribed, because more palatable. Cotton seed oil is
often substituted or mixed with the cheaper grades of olive oil. It is
wholesome, if fresh, but has not the pleasing flavor of the olive.
Many take olive oil for the purpose of rounding out the figure with
fat. If the system will assimilate fat, taken in quantities, the fat
may be stored up, but, as a rule, one is underweight because of a
failure to assimilate the regular diet and the overloading with fat
would not cause a better assimilation.
Olive oil in moderation is a good food where much heat and energy are
expended, but if ones occupation is sedentary, much fat is not required.
=Nut Oils= are good, but, with the exception of peanut butter, are not
often used.
* * * * *
[Sidenote: Sugar]
The sugars are cane and beet sugar, maple sugar, and glucose.
All sugars are carbohydrates,—carbon, hydrogen, and oxygen,—the oxygen
and hydrogen being in the same proportions as in water, (two atoms
of hydrogen and one of oxygen), the difference is that the carbon is
missing from the water.
Sugar is said to consist of about ninety-five per cent nutritive value.
=Glucose= is made by converting the starch in corn into sugar. It is
pure, wholesome, and cheap, and, for this reason, it is often used
to dilute other sugars. It is not as sweet as other sugars, and it
ferments more readily. Many of the syrups on the market are made from
it.
The common, granulated sugars are made from sugar cane or beets; beet
sugar is becoming more generally used.
Brown sugar is granulated sugar in the early stages of refinement.
Maple sugar is obtained by boiling down the sap of the maple tree. It
is often adulterated with other sugars or with glucose, because they
are cheaper. This adulteration does not make it unwholesome, but when
mixed with these it loses its distinct, maple taste and is more mild.
Before sugar can be used by the human system, it is changed into grape
sugar, or dextrose, (another form of sugar) by a ferment in the small
intestine called lactose. Milk sugar needs less chemical change than
other sugars and is taken almost at once into the circulation.
When an excess of sugar is consumed, it is stored within the body as
glycogen, until required.
Sugar is perhaps a better food than starch, because less force is
required for its digestion and it is easily assimilated, being more
readily converted into dextrose than are starches. Moreover it
furnishes the needed heat and energy to organisms that have no power to
digest starch. Milk sugar is a part of the natural food for the infant,
because the infant has not developed the ferment necessary for starch
digestion.
Sugar may be oxidized within a few minutes after eating, and, for
this reason, it is eaten by those who require to use an undue amount
of muscular strength. It yields heat and energy within thirty minutes
after eating and, in times of great exertion or exhausting labor,
the rapidity with which it is assimilated gives it advantage over
starch. Used in limited quantities, therefore, according to the
muscular or brain power exercised, sugar is one of the best foods for
the production of energy. Where much sugar is eaten less starch is
required.
It is also said to prevent fatigue, a man being able to do seventy-five
per cent more muscular work with less fatigue after consuming about
seventeen and one-half ounces of sugar dissolved in pure water.
It might be inferred from the above, that starches could be discarded
and replaced by sugars, but a small quantity of sugar soon surfeits
the appetite and if the foods were confined to those with a surplus of
sugars, sufficient food would not be eaten for the needs of the body.
This lack of appetite, occasioned by an excess of sugars, is due,
partly, to the fact that the gastric juice is not secreted as freely
when there is much sugar in the stomach.
Because of the slower secretion of gastric juice and the surfeit of
the appetite, sweetened foods are not used at the beginning of a meal,
and, while a moderate amount of sugar is desirable, a surfeit is to be
deplored.
While sugar is not converted into fat, it is so readily oxidized and
thus supplies heat and energy so promptly that the starches and fats
are not called upon until the latent energy in the sugar is used. Those
who wish to reduce in flesh should eat it sparingly that the starches
and fats may be called upon to furnish energy, but sugar should be as
freely used as the system can handle it, by those who wish to build up
in flesh.
Broadly speaking, about one-fourth of a pound of sugar, daily, in
connection with other foods, is well utilized by the system, the
quantity depending upon whether one leads an active or a sedentary life.
Candy is often made from glucose instead of molasses or cane sugar, and
while glucose is wholesome, it undergoes fermentation readily. Much
candy, unless one is actively exercising, tends to indigestion.
The desire of the child for sweets is a natural one, because it uses
so much energy, and sugar supplies this energy with less effort of the
digestive system. When the child begins to eat more solid foods, if
sugar is used in abundance for sweetening, it is no longer attracted
by the mild sweetness of fresh milk, and it is well to cut down the
allowance of sugar, when the child turns against milk, in the hope
of restoring the taste for this valuable food. Many of the best
authorities state that the child, up to its third year, should never
be allowed to taste sweets, in order that the appetite may not be
perverted from the natural sweets of milk.
Sugar is better supplied the child in a lump or in home-made candy,
rather than in the sweetening of porridge, oatmeal, or bread and milk,
etc.
Sweet fruits, fully ripened, contain much sugar and should be freely
given to the child. The natural flavor of fruits and grains is very
largely destroyed by sugar, which is used too freely on many articles
of diet.
Most vegetables and fruits contain sugar,—indeed sugar is the only
nutriment in many fruits. The sweet taste in all fruits and vegetables
is due to its presence. Sweet potatoes, beets, carrots, parsnips,
turnips, grapes, figs, and dates are especially rich in sugar and when
these are furnished with a meal, in any appreciable quantity, the
starches should be restricted—notably bread, potatoes and rice.
Harvesters, road-makers and others, who do hard work in the open air,
can consume large quantities of sugar in pie, pastry, etc., which are
difficult to digest, while one who lives an indoor life, should refrain
from an undue indulgence in these.
For one who is undernourished, sugar is a desirable food, if the starch
be diminished in proportion as the amount of sugar is increased; but
the inclination in sweetening foods is to take more starch than
the system requires, since it is the carbohydrate foods which are
ordinarily sweetened,—not the proteins.
On account of the latent heat and energy, sugars are more desirable
in cold weather than in warm. Nature supplies them more abundantly in
root vegetables for this season. More puddings and heavier desserts are
eaten in winter.
* * * * *
[Sidenote: Starch]
Starch is one of the most important carbohydrates used for nutrition.
It is formed by the chemical action produced by the sun’s rays upon the
cells of living plants, from the carbon-dioxid and water in the air and
in the soil.
Corn starch, sago, tapioca, and arrowroot are practically pure starch.
Cornstarch is from young maturing corn; tapioca is from the meal of
a tropical plant, cassava; sago is from the pith of the sago palm;
arrowroot is from a plant of the same name, a native of the West
Indies. Rice is almost pure starch, while wheat and other cereals
contain from sixty to seventy per cent.
Starch lacks flavor and for this reason all starchy foods are seasoned.
All starches must undergo much chemical change by action of the saliva,
the intestinal juice and by the liver, before they can be used by the
body. They are first converted into dextrine and then into maltose
(animal sugar). The digestion is begun by the saliva in the mouth and
continued in the stomach by the saliva swallowed with the food. If the
saliva fails to digest all of the starch, either in the mouth or the
stomach, it passes unchanged into the intestines, where it is converted
by the amylase of the intestinal juice, first into dextrine and then
into maltose, or sugar. It is absorbed into the blood as sugar. After
the digested starch (maltose) passes into the blood it is spoken of as
sugar. Before it is converted into energy it is again changed in the
liver into animal starch (glycogen) and stored for a time in the liver.
When the system is ready for it, it is again broken down into sugar,
because in the form of glycogen it cannot be absorbed into the blood.
The chemical process used in the formation of glucose, from the starch
in corn, is allied to the change in the liver, from starch into sugar.
The starches and sugars are really the “reserves” or “go-betweens” of
the body, being stored until needed.
If starches are consumed in unduly large quantities, without sufficient
exercise to burn them up, they overload the liver and clog the system.
Starchy foods should not be given to children before the starch
converting ferments are formed, nor to one in disease where these
ferments are interrupted.
Nitrogenous Foodstuffs or Proteins
The proteins form heat and energy when the supply of sugars, starches,
and fat are exhausted, but proteins, alone form muscle, bone and sinew.
They are, in this sense, the most important of foods,—they are, also,
the most costly.
The foods most rich in proteins are meat and eggs. These have undergone
chemical changes from the vegetable kingdom being built up into more
complex compounds in the animal kingdom.
Meat and eggs are the tissue builders. In this connection it may be
well to state that blood is tissue; thus meat and eggs build the blood,
as well as muscle and sinew.
Nitrogenous foods, or proteins, are so called because of the large
proportion of nitrogen which they contain. All nitrogenous foods
contain considerable carbon—mostly in the form of fat in the meat
elements—but the carbonaceous foods contain so little of the proteins
that they do not appreciably enter into the nutrition,—the carbon and
nitrogen in the carbo-nitrogenous foods are more equally divided.
The nitrogenous or protein elements in the body constitute about
one-fifth of its weight. They make the framework, forming the basis of
blood, lymph, muscle, sinew, bone, skin, cartilage, and other tissues.
Worn out body tissues is constantly being torn down and eliminated and
the protein in the foods must daily furnish material for repair, as
well as for building new tissue in the growing child.
A young animal’s first need is for growth, not having learned to
exercise sufficiently to use much energy, and the first food given is
an animal product—milk to babes and other mammals, while the young of
other animals are first fed upon eggs.
The nitrogenous foods are required in smaller bulk than vegetables and
fruits; they are more concentrated and contain less waste. According
to recent experiments, the average adult requires from two to four
ounces a day of nitrogenous foods, to repair the waste, according to
the proportion of nitrogen contained. Happily, where more is consumed,
the system has the power, up to a certain limit (depending upon the
physical condition and the daily activity), to eliminate an excess.
It is needless to say that if the daily waste is not re-supplied, the
digestion and bodily nutrition suffer. The system _must_ have the two
to four ounces to supply the nitrogen daily excreted, or the tissues
themselves will be consumed.
The proteins, of which meat is the principal one, are classified as
Albuminoids:—albumin (white of eggs), casein (curd of milk), myosin
(the basis of lean meat and gluten of wheat),
Gelatinoids, (connective tissue of meat),
Extractives (appetizing and flavoring elements).
DIGESTION
Any discussion in regard to the digestibility of foods must be general,
because food which agrees with one may disagree with another, and a
food which disagrees with one at a particular time may entirely agree
with him at some other time; therefore, before one passes upon the
adaptability of a food to the individual, it should be known that this
food agrees or disagrees with him under varying conditions.
The digestibility of food depends largely upon the physical condition
of the individual, because the amount of digestive juices poured into
the alimentary canal is influenced by this condition, particularly
by the condition of the nerves. If sufficient juices, in proper
proportions, are not poured into the digestive tract, the foodstuffs
are not made soluble for absorption into the blood. Digestion is
practically synonymous with solution,—all solid foods must be reduced
to a liquid state, through digestive juices and water, before they can
pass through the walls of the stomach and intestines.
Each individual should _learn to like_ the foods containing the
nutrient elements which experience and blood tests have shown to be
lacking in his case. The question of likes and of dislikes in regard to
foods, is largely habit, and one can learn to like almost any food one
wishes.
Where one forms the habit of discriminating too much in the food, or
discarding this food or that, because at some time it has disagreed,
due to the particular condition at the time, the mind approaches the
table as a more or less pessimistic censor and the saliva and the
gastric juices are retarded in their flow.
When one is exercising freely, so that the muscular and mucous coats
of the digestive system are strong, the body will handle foods which,
during sedentary habits, it would not digest. There are kinds of foods,
however, which, to certain individuals, according to the chemical
composition of the body, act as actual poisons, e. g., strawberries,
cheese, or coffee.
It may be well to here trace, briefly, the progress of the food through
the digestive tract and the action of the juices and the ferments upon
it.[3]
* * * * *
[Sidenote: Salivary Digestion]
The food in the mouth is mixed with saliva, which dissolves the
starches, converting them into sugar. The starches are the only foods
whose chemical digestion is begun in the mouth. They are first broken
up into dextrin and then into the more simple sugar, known as animal
starch, or _maltose_. Hereafter, in speaking of sugar, after it has
been absorbed into the blood, the reader will bear in mind that the
term refers not only to digested sugar, consumed as such, but also to
digested starches (maltose), as shown on page 63.
It is important that sufficient saliva be mixed with the food, through
mastication, that it may enter the stomach and there continue the
chemical process of digestion of starch. If starches are not thoroughly
masticated, sufficient saliva will not enter the stomach to convert the
starch into sugar; the food will pass into the small intestine, which
must then do more than its normal work of digestion.
The saliva consists of about ninety-nine and one-half per cent water
and one-half per cent solids. The solids consist of ptyalin, sodium
chlorid, sodium carbonate (baking soda), mucus, and epithelium.
Ptyalin, the most important of these, is an active digestive agent; the
mucus lubricates the masticated food; the sodium carbonate insures the
alkalinity of the food; the salt is present in all secretions; and the
water dissolves the food that the juices may more readily reach and act
upon each particle.
The saliva flows into the mouth, more or less, at all times, but more
copiously during mastication. Its evident purpose, when food is not
present, is to keep the lining of the mouth moist.
The flow of saliva is controlled, to a great degree, by nerves which
have their centers in the medulla oblongata. The sight of food,
pleasingly served, or even the thought of food which one likes, will
increase the salivary flow. This is one instance of the control of
thought materially affecting digestion, and the importance of _forming
the habit of cultivating a taste for all kinds of food_, is apparent.
The stronger the relish for the food, and the more thoroughly it is
masticated, and mixed with the saliva, the more perfect will be the
first step in digestion. This first step of thorough mastication is
all important, not only because the chemical action upon the starch
molecules is facilitated by the thorough softening and mixing with the
saliva, but thorough mastication also tends to prevent overeating.
Water encourages the flow of saliva and for this reason should be drunk
copiously before meals, particularly where digestion is weak. It may
also be taken at rest periods during the meal. (See page 44).
* * * * *
[Sidenote: Stomach Digestion]
As the food enters the stomach, the gastric juice pours out from
the mucous lining, very much as the saliva pours into the mouth. It
consists of ninety-nine and one-half per cent water and one-half per
cent solids, as does the saliva. The solids of the gastric juice are
composed of pepsin, rennin, hydrochloric acid, and mucus. The mucus
serves to lubricate the food as in the saliva. It also prevents the
digestion of the mucous lining of the stomach itself.
The hydrochloric acid and the pepsin cause the principal chemical
changes in the food while in the stomach, acting alone upon the
proteins. The only digestion of starches in the stomach is that
continued by the saliva. The salivary digestion proceeds until the
gastric juice is secreted in sufficient quantity to cause a marked
acidity of the stomach contents, when the starches are passed into the
intestines.
Gastric juice begins to flow into the stomach soon after eating, but it
is not secreted in sufficient quantity to supersede salivary digestion
for from twenty to forty-five minutes.
The result of gastric digestion of proteins is their conversion, first,
into albumin, then into proteosis and, lastly, into peptone, which is
protein in a more simple, soluble, and diffusible form. In the form of
peptone, the proteins are in condition to be absorbed.
If the food has been properly cooked and masticated the gastric
digestion will be completed in one and one-half to three hours. If not
properly cooked and masticated, the stomach digestion may continue one
to two hours longer. It should, however, be completed in three hours.
The most readily digested animal foods remain less time in the stomach.
Meat, as a rule, is easily digested, because the action of the
digestive juices of the animal has converted the starches and sugars.
The white meat of chicken, being soft, is digested in a shorter time
than the red or the dark meat.
Fluids leave the stomach more rapidly than solids. Seven ounces of
water leave the stomach in one and one-half hours, seven ounces of
boiled milk in about two hours.
The flow of gastric juice, as the flow of saliva, is governed by the
nerves;—the sight, taste, and smell of food, and the attitude of mind
toward it, to a certain extent, regulates its flow.
After the food has extensively accumulated, during the progress of
a meal, the stomach begins a series of wave-like movements called
peristaltic waves.[4] These waves work downward through the length of
the stomach towards its lower opening, known as the pyloric orifice. As
the food is moved down the stomach by these motions, it is thoroughly
mixed with the gastric juice.
During the early stages of digestion, the sphincter muscles of the
pylorus keep the lower end of the stomach closed, but, as digestion
progresses, the pylorus gradually relaxes to let the digested, soluble
portion of the food pass into the intestine. If the food still remains
in a solid form, by reason of being improperly cooked or poorly
masticated, as it touches the pylorus, these sphincter muscles, almost
as if they were endowed with reasoning faculties, close, forcing the
undigested mass back to be further acted upon by the gastric juice,—the
solid mass is not allowed to pass until dissolved.
If the individual continues to abuse the stomach and to cause it to
work overtime, it becomes exhausted and demands rest; it refuses to
discharge the gastric juice in proper proportion; the peristaltic
movements are weak; and food is not promptly or forcefully moved along
the stomach and mixed with the gastric juice. This demand for a rest is
termed _Indigestion_.
To sum up,—digested sugar is dextrose; digested starch is first
dextrin, then maltose (animal, sugar); digested protein is peptone;
and, digested fat is saponified fat.
* * * * *
[Sidenote: Intestinal Digestion]
The food passes from the stomach, through the pylorus into the small
intestine. The first twelve inches of the small intestine is known as
the duodenum. In the duodenum it is acted upon by the pancreatic juice
from the pancreas, the bile from the liver, and the intestinal juices.
These juices act upon proteins, fats, and carbohydrates. The bile acts
upon the fats, while the pancreatic and intestinal juices act chiefly
upon the carbohydrates.
As the food enters the intestine, it is changed, by the sodium
carbonate, from the acid condition produced in the stomach, to alkaline
reaction.