TABLES OF DIGESTIVE HARMONIES AND DISHARMONIES

Vegetables

(Leafy or succulent vegetables as lettuce, spinach).
Fresh peas, carrots, parsnips, etc.—Potatoes being starchy, not included.

TABLES OF DIGESTIVE HARMONIES AND DISHARMONIES

Acid Fruits

(All acid and subacid fruits as listed in Lesson VIII)

TABLES OF DIGESTIVE HARMONIES AND DISHARMONIES

Sweet Fruits

(All non-acid fruits as listed in Lesson VIII)

TABLES OF DIGESTIVE HARMONIES AND DISHARMONIES

Sugars

(Cane and maple-sugars, sirup, and honey)

Lesson XIII

LESSON XIII

Simple Classification of Foods

While there is a dominating substance in all foods, yet they usually contain many compounds which render them, from a chemical standpoint, very difficult to classify accurately. For example, the principal nutrients in wheat are carbohydrates (starch and sugar), yet wheat contains mineral salts, fat, and protein, the latter being a compound consisting of carbon, hydrogen, oxygen, nitrogen, and sulfur. Wheat would, therefore, be placed in the carbohydrate class, but it would overlap into several other classes. What is true of wheat, is true of nearly all other articles of food. Furthermore, foods do not chemically reproduce themselves when taken into the body, but in the process of metabolism they are converted either into other elements or into other compounds. From this it will be understood that the articles listed under the following headings are classified according to the nutritive substance which predominates in them, and are given for the purpose of guiding the practitioner in the selection of such foods as will supply the various chemical constituents of the body.

Foods which contain two or more substances in generous proportions may appear under two or more of the following headings, as in the case of peanuts. This humble article of food contains 19 per cent carbohydrates, 20 per cent protein, and 29 per cent fat, hence it is listed under the three headings—carbohydrates, proteids, and fats.

The tables comprise the best selections of food available in all countries and at all seasons of the year. They contain everything the body needs under the varying conditions of age, climate, and activity, except, perhaps, in some parts of the frigid zone.

In compiling these tables I have selected only such articles of food as experience has proved most useful.

SIMPLE CLASSIFICATION OF FOODS BASED ON PRINCIPAL NUTRITIVE SUBSTANCES

PURPOSES WHICH THE DIFFERENT CLASSES OF FOOD SERVE IN THE HUMAN BODY

While all the articles of food in the four above-named classifications contain other elements than the one under which heading they appear, yet the body uses or appropriates them for the following purposes:

PURPOSE OF CARBOHYDRATES

The carbohydrate substance in food is used by the body chiefly for the purpose of keeping up body-weight; that is, for the purpose of supplying the various fluids which fill the cell-structure. If one is suffering from emaciation, the carbohydrate element in food should predominate. While some of the more soluble proteids, especially milk and eggs, will give a rapid gain in weight, the weight will not be permanent unless sufficient carbohydrates are taken to supply the blood with all the required elements of nutrition, or, in other words, to level or to balance the body requirements.

PURPOSE OF FATS

Fats are used by the animal body primarily for the purpose of producing heat. Food is burned or oxidized in the blood, undergoing very much the same action as does the combustion of coal in a grate. The heat thus generated is delegated to the blood, and the blood, by its circulation, distributes this heat throughout the body. The carbon dioxid or waste matter formed during the circulation, is carried to the lungs, where it reunites with the oxygen which we breathe, and thereby again passes back into the atmosphere.

PURPOSE OF PROTEIDS

Proteid is a compound containing chiefly nitrogen, oxygen, and carbon. Its purpose is to form the muscular and the tissue structure of the body. To use a homely illustration, proteid may be compared to the material which makes the honeycomb, while the carbohydrate substance may be compared to the honey; that is, to the fluids which fill the cells.

Those performing heavy or active muscular labor should eat liberally of the proteid class of foods.

Under normal conditions, natural hunger will call for the quantity of proteid needed. The tendency, however, should be toward the minimum; that is, one should take the lowest quantity of proteid that the body requires to keep up the cell-structure. (See Lesson VI, p. 216.) Modern investigations have shown that, in many cases of extreme athletic tests, a low proteid diet has given the greatest endurance. This is accounted for by the fact that nearly all carbohydrates, especially of the grain family, contain from 8 to 12 per cent of proteids, which is quite sufficient, in many instances, to supply the body with all the tissue-building material necessary.

Inasmuch as the several nutritive elements found in a single article of food are better proportioned by Nature, than man can usually proportion them, the relation of one substance to another will be better divided if the entire meal be made to consist of only one kind of food, and both digestion and assimilation will therefore be more perfect. Under these conditions the blood will be laden with very little waste matter, which is the thing that reduces our powers of endurance. Therefore, when it is possible to secure the carbohydrate, the proteid, and the fatty substances from a single article of food which will give to the body greater strength and endurance than when we secure these substances from several sources, we should confine our menus to single articles of well-proportioned food. This thought, carried to its logical end, leads one more and more, as experience progresses, toward the mono-diet system.

PURPOSE OF MINERAL SALTS

Mineral salts serve two distinct purposes in the body:

1 They assist in building up the cartilage and the body-structure

2 They assist in the digestion, and in the dissolution of other foods, especially of the carbohydrate group, and more especially of the grain family

Grains are very difficult to subdivide into their constituent elements; that is, to reduce to a solution so fine that assimilation will be perfect. A liberal use of the foods containing mineral salts aids very materially in this process of solution.

DIFFERENCE BETWEEN DIGESTIBILITY AND ASSIMILABILITY

The true interpretation of the word "digestion" is the preparation of food by the action of:

1 The saliva

2 The gastric juice

3 The bile, and

4 The pancreatic juice

When food is properly prepared by mastication by the time it reaches the pancreas, it should be thoroughly split up or subdivided, in which state it is ready for assimilation.

The true interpretation of the word "assimilation" is the absorption of all food substances through the walls of the intestinal tract, and the final passing of them into the circulation.

It is nothing unusual, however, for a person to become afflicted with predigestion, and, at the same time, with poor or faulty assimilation; in other words, digestion being too rapid, and assimilation being too slow. This condition frequently occurs in cases of superacidity. On account of the excess of acid, the food digests or passes from the stomach prematurely; that is, before it has been dissolved by the action of the hydrochloric acid. The food, thus super-charged with acid, passes from the stomach into the lower intestines, and sets up a condition of irritation. This irritation or swelling of the mucous surface (lining) of the intestines, closes the small canals, or winking valves, as they are sometimes called, thus seriously interfering with the passing of the dissolved food matter into the circulation.

The following table is designed to show the comparative assimilability of the leading articles of food, together with their starch, sugar, and water content:

TABLE SHOWING COMPARATIVE ASSIMILABILITY AND CARBOHYDRATE AND WATER CONTENT OF CEREALS, LEGUMES, AND VEGETABLES

* While all the vegetables mentioned in the above table belong to the carbohydrate class, yet the starch element contained in them is very much more assimilable than the starch contained in grains or legumes, therefore these vegetables may be eaten freely by those having rheumatic or gouty tendencies.

The starch and the sugar content in fresh vegetables appears low owing to the fact that they contain a large percentage of water. Eliminating the water, these foods rank in their starch and sugar content with cereals and legumes, and are much more easily digested and assimilated. In other words, if the chemist should reduce the water content to the same per cent as that of cereals, the carbohydrate content would rise in the same ratio as the water content is reduced. Both the starch and the sugar content of these vegetables is more digestible, and more readily assimilated than the starch and the sugar found in cereals and legumes.

PURPOSE OF THE VIENO TABLE

The student should remember that not only the quantity but the quality of food must be considered. The vieno system of food measurement, as herein explained, is the simplest system of food measurement that has ever been published. It is amply complete, and accurate enough for the purpose for which it is intended, and that is the calculation of the energy and the available nitrogen contained in natural dietaries.

This measurement is really a quantitative measurement; that is, it measures the quantity, not the quality. In order to have a full knowledge of a bill of fare, it is necessary to know, in addition to the quantity, the exact chemical nature of each particular food, and also to know the other foods with which that food will combine.

This food table tells accurately the amount of energy that may be derived from food by chemical analysis, but it does not tell the amount of energy that the body must expend in the work of assimilation. This cannot be given in a table, because it varies with the individual and the condition of his digestive organs.

LESSON XIV

Heat is another form of energy. Heat and work can be converted into each other. The steam-engine turns heat into work, while a "hot box" on a car-wheel is a case of work being turned back into heat.

Experience shows that a definite amount of heat will yield a definite amount of work, so that the amount of heat produced by a given amount of food, when combined with oxygen, is taken as a measure of its energy. This is ordinarily expressed in calories, a calorie being the amount of heat required to raise the temperature of one thousand grams of water one degree on the centigrade thermometer scale.

The use of these terms need not concern the student. Instead of using the calorie I will use a unit which is equal to one hundred calories. I have selected a unit of this size because it gives about the ordinary service of food at meals which is easily measured and remembered.

NITROGEN

Nitrogen is the chemical element that is most concerned with the function of life. All animal tissue contains nitrogen, which forms about one-sixth part, by weight, of all the nitrogenous or protein substances.

If we were to take a hundred pounds of lean meat, or muscle, and evaporate from it all the water, we would have about eighteen pounds of dry material left. If we should analyze this dry substance, we would find that about one-sixth, or three pounds, would be the element nitrogen. Thus we say that muscle contains eighteen per cent of protein, or three per cent of nitrogen. In ordinary practise the protein is mixed with fats and salts, and cannot be measured by simply drying out the water, so the chemist finds the amount of nitrogen present and multiplies by 6.25, which gives about the correct per cent of protein. This method is not exact because the per cent of nitrogen in various proteids is not always the same, but it will give an intelligent average. I will discard the use of the term protein, and refer to the amount of nitrogen directly.

All compounds of the element nitrogen are not available as food. For example: The nitrogen of the air, of ammonia gas, or gunpowder cannot be utilized in the animal body. The nitrogen in foods only refers to available nitrogen. Compounds containing other forms of nitrogen are not foods, but are frequently poisons.

SYSTEMS OF FOOD MEASUREMENTS COMPARED

THE "OLD" SYSTEM

Under the old system of food measurement, feeding the human body cannot be made a practical science for the masses, therefore a new system becomes necessary. That we may more fully appreciate the value of a new system, let us consider the methods hitherto available.

Suppose a man is using two quarts of milk a day, and wishes to determine the amount of available nitrogen or tissue-building material and energy it contains. Under the old system he must get a book on food analysis, or send to Washington for a Government bulletin. If he does not understand the meaning of the terms and figures used, the tables would be useless to him until he goes to a chemist to have them explained. He is now ready to work out the nutritive value of his milk, and proceeds as follows:

First, he gets the number of cu cm in the milk, thus—952.8 (number cu cm in 1 quart) x 2 = 1905.6, number of cu cm in 2 quarts of milk. Second, he gets the weight of his milk in grams—1.032 (number grams in 1 cu cm of milk) x 1905.6 = 1966.57, number of grams in 2 quarts of milk.

He now turns to a table of analysis which tells him that milk contains 3 per cent of protein, 3½ per cent of fat, and 4½ per cent of sugar. As the amount of nitrogen in milk is approximately one-sixth of its entire protein, he would now get 16 per cent of the 3 per cent (.16 x .03 = .0048), which is the percentage of nitrogen contained in milk.

His next step would be—1966.57 (number grams in 2 quarts of milk) x .0048 = 9.44, the number of grams of nitrogen in 2 quarts of milk.

I will not explain the way in which the energy would have to be figured, but will merely give the arithmetical processes by which the result is obtained:

3  ×  4.1  =  12.3
3.5  ×  9.3  =  32.55
4.5  ×  4.1  =  18.45
12.3  +  32.55 + 18.45 =  63.30
1966.57  ×  63.30 = 124483.88
124483.88  ÷  100 =  1244, the No. of calories or energy (heat units) contained in two quarts of milk.

THE NEW OR "VIENO" SYSTEM

To a unit of food-energy which is equal to one hundred calories (see last paragraph on "Energy"), I have given the name of Vieno, derived from "vital" and "energy," and pronounced vi-eń-o. The Vieno system, therefore, will measure all foods by vi-en-os, or units of energy equal to one hundred of the chemist's calories. One vieno of milk is one-sixth of a quart, or two-thirds of an ordinary glass. From this it is readily seen that two quarts of milk will give twelve vienos of energy, or, if we wish to express it in the chemist's term, twelve hundred calories.

The table also states that milk has a nitrogen factor of .8. Therefore, if we wish to know the amount of nitrogen in the two quarts of milk, all we need do is to multiply the number of vienos by the nitrogen factor; 12 x .8 = 9.6, which figure represents the nitrogen consumption expressed in grams. (See explanation of fourth column of table.) These results are practically the same as those obtained by the old system of computation, but expressed in simpler terms. Thus we see that the vieno system of computing food values is unique in its simplicity, and will be a very material aid in putting Food Science on a practical basis.

NECESSITY FOR A SIMPLE SYSTEM

Things are commonly measured by volume, or by weight. That volume could not be made sufficiently accurate in the measurement of food values is evident. A bushel of lettuce leaves would contain much less food value than a bushel of wheat. Weight would seem to be a fairer way to compare foods, but all foods contain water, which may vary from five to ninety-five per cent. A pound of turnips, which is nine-tenths water, would not be comparable with sugar, which has scarcely any water.

Even if it were not for the water, weight would not be a fair method of comparison because some foods are of more value per pound than others, owing to their difference in chemical composition. For instance, a pound of butter gives about two and one-fourth times as much heat to the body as sugar.

As before mentioned, the two chief food factors which we ought to measure are energy-producing and tissue-building power.

All true foods when assimilated in the body produce some energy. In fact, only such substances as produce bodily energy, when combined with the oxygen taken in through the lungs, can be correctly termed food.

I have taken this energy-producing power of food as the best basis for measurement and comparison. The nitrogen could have been taken as a unit, and the energy figured by a table, but it is simpler to use energy as a unit (as given in column 3, p. 655), and figure the nitrogen in the various foods by means of a table which gives the amount of nitrogen per unit of energy. (Column 4, p. 655.)

Multiplication of units of energy (column 3) by the nitrogen factor (column 4) is necessary because the ratio of nitrogen to energy is different in each food.

EXPLANATION OF TABLE

In the table that follows, I have attempted to give in the simplest way the amount of each particular food that one vieno equals.

The second column shows, in the plainest language possible, what one vieno of food equals—as, one vieno of barley equals one ounce; or, one vieno of nuts equals one rounded tablespoonful, etc. This method is, of course, only approximate, as in some foods it is impossible to find a simple term to express the amount of one vieno. This is especially true of cooked foods because of the varied amounts of water contained. In such cases the way for the student to become familiar with a vieno is to weigh one pound of the raw material, and, after it is cooked, weigh it again, and then calculate the water content.

The definition given in the second column in the case of milk, butter, eggs, and cheese is fairly accurate. The description given in the case of cereals and bread is also fairly accurate. In the list of fresh vegetables, no attempt has been made to describe one vieno by volume, as, vegetables being loose and bulky, it is practical to measure them only by weight.