What to eat and when

In the previous chapters, we have given the classification of the elements in foods (foodstuffs) which supply the body needs. In this chapter the foods commonly used are classified according to the predominance of these elements.

CARBONACEOUS FOODS

While all foods contain a combination of elements, some contain a greater proportion of carbohydrates and fats, and are classed as carbonaceous.

Of the carbohydrates, next in importance to the sugars and to the starches in their purest form (cornstarch, tapioca, sago, and arrowroot), come the roots and tubers, such as potatoes, sweet potatoes, beets, parsnips, turnips, and onions.

The following table shows the proportion of various foodstuffs in these vegetables. The skins of the vegetables are included.

TABLE I
Roots and Tubers

Potatoes. It will be noted from the table given above that sweet potatoes contain a larger percentage of carbohydrates, hence they produce more heat and energy than any other vegetable; next to the sweet potato comes the Irish or white potato.

While the white potato contains two per cent. of protein, this is almost all located in a very thin layer immediately beneath the skin, so that when the potato is peeled in the ordinary way, the protein is removed. This is true of many vegetables. They lose their distinctive flavor, as well as their value as tissue-building foods, when the skins are removed, especially before cooking. Many vegetables may be peeled after being cooked and their value in nutrition is thus increased. All tubers gain in dietetic value if they are cooked in their skins, the thin outer covering being removed after the cooking process is completed. The ordinary cook, however, is unwilling to take the trouble to prepare them in this way.

In vegetables as usually prepared for the table the proportion of carbohydrates is increased and the proportion of protein is diminished. The skins render many of the foods unsightly, hence they are discarded in the preparation for cooking.

When a potato is baked the outer skin is readily separated from the less perceptible layer containing the protein. Potatoes boiled in their skins retain the protein.

In the white potato, of the twenty-two per cent. of carbohydrates, three and two-tenths per cent. is sugar and eighteen and eight-tenths per cent. is starch. In the sweet potato ten and two-tenths per cent. is sugar and sixteen per cent. is starch.

Since sugar digests more quickly than starch, the sweet potato digests more quickly than the white. Because of the large percentage of carbohydrates in each, it is a mistake to eat these two vegetables at the same meal, unless the quantity of each is lessened. For the same reason, bread and potatoes, or rice and potatoes, should not be eaten to any extent at the same meal, unless by one who is doing heavy manual labor, requiring much energy.

Onions. Only about four per cent. of the onion represents nourishment; the eleven and three-tenths per cent. of carbohydrates is made up of two and eight-tenths per cent. sugar and the rest of extractives. Of the extractives the volatile oil, which causes the eyes to water when onions are peeled, is the most important.

The onion is not, therefore, so important for its actual nourishing qualities as for its relish and flavor, and for this it is to be commended.

It is a diuretic, encouraging a free action of the kidneys. Because of its diuretic value it is commonly called a healthful food. An onion and lettuce sandwich stimulates the action of the kidneys and is a nerve sedative.

The volatile oil makes the raw onion difficult for some to digest and, in that case, should be omitted from the diet.

Beets. There is no starch in beets, their seven and three-tenths per cent. of carbohydrates being sugar. They possess, therefore, more nutritive value than onions, and they are easily digested. It will be noted that it takes many beets to make a pound of sugar.

There are no more delicate or nutritious greens than the stem and leaf of the beet. These greens contain much iron and are valuable aids in building up the iron in the blood, thus aiding in the correction of anemia.

Carrots. Carrots are valuable as food chiefly on account of their sugar. They are somewhat more difficult of digestion than beets and they contain more waste. They make a good side dish, boiled and served with butter or cream.

Turnips. Turnips have little value as a food. Their nutriment is in the sugar they contain. For those who enjoy the flavor they are a relish, serving as an appetizer, and, like the onion, are to be recommended as a side dish for this purpose.

Parsnips. Like carrots, parsnips are chiefly valuable for their sugar and for the extractives which act as appetizers.

Since turnips, carrots, onions, and parsnips owe a part of their nutritive value to the extractives which whet the appetite for other foods, it follows that, if one does not enjoy their flavor or their odor, these vegetables lose in value to that individual as a food. If one does enjoy the flavor, it adds to their food value, therefore taste for the flavors of all foods should be cultivated.

The question may be asked with reason: “Why do we eat green vegetables?” They contain only about four per cent. nutriment, as will be seen in Table II, and are mostly made up of water and pulp. It will be noted that they are distinctly lacking in protein and in carbohydrates; hence, they have little food value.

Some of them, however, contain acids which tend to increase the alkalinity of the blood, and salts which are needed by the system.

Their merit lies in the fact that they have distinct flavors and thus whet the appetite. Another reason why green vegetables are thoroughly enjoyed is because they come in the spring, when the appetite is a little surfeited with the winter foods.

They are diuretic, helping the kidneys and the skin to rid the system of waste.

Because of their bulk of waste they are useful in constipation as they act as a stimulus to the peristaltic action of the bowels; thus they are more laxative to the intestines than the root vegetables, partly because of the salts which they contain and partly because of the undigested vegetable fiber. This vegetable fiber, being coarse, assists in cleansing the mucous lining of the stomach and intestines. They are diuretic and, if for no other reason than for this cleansing of the kidneys, and to make the stomach and intestines more efficient, the use of green vegetables is to be commended, and it is well to eat freely of them.

TABLE II
Green Vegetables

In larger cities, fresh vegetables are in the markets the year around, but if they are raised in greenhouses, or in any way forced, they lack the flavor which comes with natural maturity and they also lack the full amount of iron given by the rays of the sun. If raised in the south and shipped from a distance, they are not fresh and they do not have as good an effect on the system as when fresh and fully matured by the sun.

Greens, as spinach, chard, dandelions, and beet tops, as previously stated, contain iron and build red blood corpuscles.

Cabbage, of which there are many varieties, contains much sulphur. If fermentation exists in the intestines the sulphur unites with hydrogen causing gas of an unpleasant odor.

They promote the formation of calcium oxalate in the urine and should be avoided as a food by any one inclined to gout, rheumatism, or gall-stones.

Cabbage is usually not well digested by invalids.

Eaten raw, because of its bulk, it is laxative. Some dyspeptics, who cannot digest cooked cabbage, digest raw cabbage readily.

Celery is wholesome when cooked, because of the milk and butter in which it is prepared. Eaten raw the fiber is hard for the digestive juices to dissolve and should be thoroughly masticated. It has little nutritive value save for its appetizing flavor.

Because of the salts, largely sulphates and phosphates, which it contains, celery has been called a nerve food, but the proportion of these is so small that their food value is negligible.

Tomatoes are easily digested and are refreshing. They are not well borne by some and on account of the oxalic acid they contain should not be used by those having an excess of uric acid.

Asparagus, because of its delicate flavor and appearance early in spring, is a vegetable universally liked. It is easily digested and may be eaten by invalids; they usually greatly relish it. Its particular food value lies in its sulphur and in its value as an appetizer.

Rhubarb is one of the most wholesome of vegetables and is being much more widely used. Thoroughly cooked it is digestible and a natural laxative.

Its tart flavor and appearance in early spring render it a pleasant change from the ordinary diet. Eaten in excess, like cabbage, it produces calcium oxalate in the urine and should not be eaten in large amounts by those inclined to gout.

All fresh vegetables should be masticated to almost a fluid consistency; otherwise, they are difficult of digestion, containing, as they do, so much fiber.

Technically speaking, fruits include all plant products which bear or contain a seed. They are valuable for their acids and organic salts—citrates, malates, or tartrates of potassium, sodium, magnesium, and calcium.

They are composed for the most part of starch, sugar, water, and various organic acids, cellulose, and pectin. (Pectin is the substance which jellies under heat.) Fruits which do not contain pectin must be combined with others which do, or with gelatin, if jelly from them is desired.

The organic acids in fruits are readily split up in the body, and form alkalis. For this reason acid fruits are useful in certain acid conditions of the stomach, because they combine with the stomach acids, liberating substances which cause an alkaline reaction.

The citrus fruits—oranges, lemons, grapefruit and limes—are rich in citric acid.

Malic acid is found in gooseberries, peaches, pears, apples, currants, and apricots.

Tartaric acid is prominent in grapes.

The value of fruits as a food depends largely on the amount of starch and sugar they contain, though their agreeable odor and taste, by furnishing variety in the diet, render them, also, of great value as appetizers.

As a rule they contain too much water to be of great food value if eaten alone.

The organic acids and salts contained in fruits are of value as they stimulate the activity of the kidneys and lessen the acidity of the urine. The urine may even be rendered alkaline by them; hence, when a test shows evidence of too much uric acid, acid fruits are used to neutralize the acids in the tissues, particularly the acids of the citrus fruits.

The fruit juices are readily absorbed and the potassium calcium, sodium, and magnesium they contain are liberated with the formation of alkaline carbonates.

These alkalis are largely eliminated through the kidneys, which accounts for the diuretic effect of fruits, their acids and salts stimulating the activity of the kidneys.

The seeds in the small fruits are not digested, but they serve the purpose of increasing intestinal peristalsis and of assisting the movement of the contents of the intestines. The skin and the fiber of fruits also assist the intestines in this way, just as the fiber in vegetables does.

All acid fruits—particularly lemons, limes, grapefruit, and oranges—stimulate the action of the skin as well as the kidneys and whenever the kidneys and skin are not sufficiently active, these fruits should be eaten freely.

In case of an excess of hydrochloric acid in the stomach, lemon juice or citrus fruits are valuable about half an hour before a meal, as when taken on an empty stomach they decrease the secretion of hydrochloric acid.

When the secretion of hydrochloric acid is limited, acids are given after a meal to supplement the deficiency, or stimulate the glands to activity.

Sweet or bland fruits are those containing a lesser percentage of acids. Among these are pears, raspberries, grapes, bananas, blackberries, blueberries, melons, and some peaches, apples, and plums.

Of this class of fruits, dates, figs, prunes, and grapes (raisins), furnish most nutriment, because, as will be noted by Table III, these fruits contain a large amount of carbohydrates in the form of sugar.

The protein in these sweet fruits is largely in the seeds and, as the seeds are not digested, they have no real food value for the individual.

Figs and prunes, peaches, apples, and berries are laxative—probably the laxative action of figs and berries is due to the seeds, and of the others to the salts and acids they contain, and to the cellulose or fibrous material which furnishes bulk.

TABLE III
Fruits

The astringent and acid taste of unripe fruits is due to the tannin and the acids. Oxygen is necessary to ripen fruits and the slow natural maturing of the fruit on the tree enables the oxygen to enter into combination with these substances, lessening their reaction and altering the starch into glucose or levulose.

Fruits ripened artificially lack this chemical action of sun and oxygen, hence the decreased palatability and digestibility of fruits so ripened. If underripe fruits are freely eaten they ferment in the alimentary tract and this fermentation causes the colic, vomiting, and diarrhea so often experienced. Overripe fruit, from the decomposition products which have already begun to form and which are further released in the stomach or bowels, may produce the same results.

Care should therefore be exercised to select thoroughly ripe fruits which have not begun to decay.

In order to reach their destination in fair condition, outwardly, many fruits are picked before they are ripe. Bananas are commonly picked green, because they decay so quickly that if they were picked ripe they would spoil before reaching the northern markets.

One test of a naturally ripened apple is to cut it with a steel knife—if the blade turns black, or if the cut surface of the apple turns brown in a few minutes, it should not be eaten, for it indicates an excess of tannin. It is this tannin which gives the small boy excruciating pains from his green apples.

It will be recalled that the tannin from the bark of trees toughens the skin of animals and forms leather. The effect on the membrane of the stomach and intestines, from the tannin in food, is not so pronounced, because of the activity and resistance of living matter.

The juice of lemons and oranges is most valuable in seasickness and scurvy, and is of benefit in nausea. A slice of lemon will often clear a coated tongue and give a refreshing sense of cleanliness to the mouth, especially in feverish conditions. Sour lemonade is one of the best drinks in summer because of its thirst-allaying qualities.

Table III shows that bananas contain nearly twenty-three per cent. of carbohydrates, which, in an immature state, are largely starches. The natural ripening process changes the starch to sugar, thus making them more easily digested. The starch globules, when not matured on the tree, are not easily broken and are thus difficult of digestion.

Bananas should not be given to children under two years of age because before this age the ptyalin and pancreatin are not sufficiently developed to digest the starch.

Many of the inhabitants of the tropics use bananas almost to the exclusion of other food and appear well nourished. They obtain them from the tree when the fruit has thoroughly ripened, the starch having been transformed by Nature into an easily digested product.

The reason many find they cannot digest bananas, as purchased in our markets, is due to the fact that the fruit is immature and unripe.

The banana meal or flour is usually thoroughly digestible, is nourishing, and has an agreeable taste. Invalids can often take banana meal in the form of gruel; it makes an appreciated addition to a limited diet. Made into a porridge and eaten with cream it is valuable in conditions of inflammation of the gastro-intestinal tract. The addition of a few drops of lemon juice renders it palatable to those who like an acid flavor. Children enjoy it as a variation from cereals. It is relished by typhoid fever patients as a change from milk.

It must be carefully cooked and well prepared as, like oatmeal, it can be spoiled by insufficient or poor cooking. Owing to the limited demand it is not obtainable in all markets, as it has not yet become popularized.

Grapes, because of their wholesome qualities, are useful to the system, as they contain sodium, iron, magnesium, potassium, and calcium. Because of their appetizing flavor they are universally enjoyed, and because they are cheap are universally used. The skins and seeds are indigestible and, if swallowed, may cause severe irritation or obstruction of the intestines. Grapes are rich in sugar, and on this account must not be eaten by diabetics.

Grape juice, when unfermented, is a valuable drink, in health, or for the convalescent. It is agreeable in taste and is mildly laxative. Added to other fruit juices, as lemon or orange, it allays thirst and furnishes a pleasant flavor, but on account of its high percentage of sugar does not allay thirst when used alone.

Apples, so universally used, are easily digestible when ripe, and may be prepared in so many ways that they constitute a valuable addition to the diet. Their laxative qualities, when taken on an empty stomach, as before breakfast, or just before retiring, are well known. They are thus valuable in constipation, and in some forms of dyspepsia may, with benefit, be eaten raw.

Apples should be thoroughly masticated.

The apple peel contains potassium salts and should be eaten with the fruit.

Most invalids digest apples better if they are cooked, especially baked. Stewed apples may have the beaten white of eggs whipped into them and invalids who revolt against eggs can take them thus prepared.

Because of the sugar necessary in cooking them they should be avoided by diabetics, and in conditions in which there is irritation of the gastro-intestinal tract.

Quinces are indigestible when raw, but well baked and eaten with cream are appetizing and nourishing.

Pineapples, if thoroughly ripe, contain a ferment which will digest protein, rapidly softening and disintegrating the tissue of meat. Like the pancreatic ferment it acts in both alkaline and acid mediums. Pineapple juice, therefore, is exceedingly valuable as an addition to the diet. The coarse fibers also have a laxative action. Care must be taken, however, to use this fruit only when it is well ripened, as when green, it is indigestible.

The juice of pineapple, because of the action of the ferment in dissolving tissue, is valuable in many forms of sore throat, particularly when accompanied by an ulcerous condition. The effort should be made to hold it in the mouth, allowing it to trickle down the throat by degrees.

Dried fruits are less palatable than fresh. Many of them, as prunes and raisins, are nourishing, but others, as citron, are indigestible, and should be finely chopped if used as flavoring.

Dried or evaporated fruits, through the action of heat, either artificial or from the rays of the sun, have lost the water they contained, and are preserved by their own sugar.

Dried grapes, or raisins, because of their sugar, soon satiate the appetite if eaten raw, but if cooked or added to cereals, puddings, or breads, enhance the palatability and nourishing qualities of these foods.

Dates and figs used in the same way, in cereals or puddings, are equally valuable.

Dried currants are the most indigestible of the dried fruits, owing to their large amount of skin in proportion to the nutriment.

NITROGENOUS FOODS

As previously stated, in a mixed diet, meat and eggs are the chief sources of nitrogenous foods. Next to these come the legumes.

Meat is composed largely of muscle fiber and contains connective tissue and fat. It has been estimated that beef contains one-third nutritive material, the other two-thirds being water and bone. Fat meat contains less nitrogenous material and less water than lean meat.

Lean meat is almost entirely digested in the stomach by the gastric juice, which changes it into peptone. It is needless to say that it should be thoroughly masticated, that the gastric juice may promptly act on it. If any part passes into the intestine undigested, the process is continued by the trypsin of the pancreatic juice.

The peptone is absorbed and carried by the blood and lymph to all tissues of the body, where it is used for growth and repair. As stated under “Heat and Energy,” any excess of protein above that needed for growth and repair is oxidized if sufficient oxygen is breathed, yielding energy and heat, and the waste is eliminated through the kidneys and the bile.

For purposes of comparison, one pound of beef has been said to equal in nutritive value, two and one-half pints or five glasses of milk, one-half pound (two-thirds of an ordinary baker’s loaf) of bread, and three eggs. However, these values vary.

TABLE IV
Animal Foods