Important Articles of Diet.
107. Milk. The value of milk as a food cannot be overestimated. It affords nourishment in a very simple, convenient, and perfect form. It is the sole food provided for the young of all animals which nourish their young. It is an ideal food containing, in excellent proportions, all the four elements necessary for growth and health in earlier youth.
| Careful analyses have beenmade of the different articles of food, mostly of the raw, or uncookedfoods. As might be expected, the analyses on record differ more or less inthe percentages assigned to the various constituents, but the followingtable will give a fair idea of the fundamental nutritive value of the morecommon foods: | ||||||
| In 100 parts | Water | Proteid | Fat | Carbohydrate | Ash | |
|---|---|---|---|---|---|---|
| Digestible | Cellulose | |||||
| Meat | 76.7 | 20.8 | 1.5 | 0.3 | — | 1.3 |
| Eggs | 73.7 | 12.6 | 12.1 | — | — | 1.1 |
| Cheese | 36-60 | 25-33 | 7-30 | 3-7 | — | 3.4 |
| Cow’s Milk | 87.7 | 3.4 | 3.2 | 4.8 | — | 0.7 |
| Wheat Flour | 13.3 | 10.2 | 0.9 | 74.8 | 0.3 | 0.5 |
| Wheat Bread | 35.6 | 7.1 | 0.2 | 55.5 | 0.3 | 1.1 |
| Rye Flour | 13.7 | 11.5 | 2.1 | 69.7 | 1.6 | 1.4 |
| Rye bread | 42.3 | 6.1 | 0.4 | 49.2 | 0.5 | 1.5 |
| Rice | 13.1 | 7.0 | 0.9 | 77.4 | 0.6 | 1.0 |
| Corn | 13.1 | 9.9 | 4.6 | 68.4 | 2.5 | 1.5 |
| Macaroni | 10.1 | 9.0 | 0.3 | 79.0 | 0.3 | 0.5 |
| Peas and Beans | 12-15 | 23-26 | 1½-2 | 49-54 | 4.7 | 2-3 |
| Potatoes | 75.5 | 2.0 | 0.2 | 20.6 | 0.7 | 1.0 |
| Carrots | 87.1 | 1.0 | 0.2 | 9.3 | 1.4 | 0.9 |
| Cabbage | 90 | 2.3 | 0.5 | 4-6 | 1-2 | 1.3 |
| Fruit | 84 | 0.5 | — | 10 | 4 | 0.5 |
Cheese is the nitrogenous part of milk, which has been coagulated by the use of rennet. The curd is then carefully dried, salted, and pressed. Cheese is sometimes difficult of digestion, as on account of its solid form it is not easily acted upon by the digestive fluids.
108. Meats. The flesh of animals is one of our main sources of food. Containing a large amount of proteid, it is admirably adapted for building up and repairing the tissues of the body. The proportion of water is also high, varying from 50 to 75 per cent. The most common meats used in this country are beef, mutton, veal, pork, poultry, and game.
Beef contains less fat and is more nutritious than either mutton or pork. Mutton has a fine flavor and is easily digested. Veal and lamb, though more tender, are less easily digested. Pork contains much fat, and its fiber is hard, so that it is the most difficult to digest of all the meats. Poultry and game have usually a small proportion of fat, but are rich in phosphates and are valued for their flavor.
109. Eggs. Consisting of about two-thirds water and the rest albumen and fat, eggs are often spoken of as typical natural food. The white of an egg is chiefly albumen, with traces of fat and salt; the yolk is largely fat and salts. The yellow color is due partly to sulphur. It is this which blackens a silver spoon. Eggs furnish a convenient and concentrated food, and if properly cooked are readily digested.
110. Fish. Fish forms an important and a most nutritious article of diet, as it contains almost as much nourishment as butcher’s meat. The fish-eating races and classes are remarkably strong and healthy. Fish is less stimulating than meat, and is thus valuable as a food for invalids and dyspeptics. To be at its best, fish should be eaten in its season. As a rule shell-fish, except oysters, are not very digestible. Some persons are unable to eat certain kinds of fish, especially shell-fish, without eruptions on the skin and other symptoms of mild poisoning.
111. Vegetable Foods. This is a large and important group of foods, and embraces a remarkable number of different kinds of diet. Vegetable foods include the cereals, garden vegetables, the fruits, and other less important articles. These foods supply a certain quantity of albumen and fat, but their chief use is to furnish starches, sugars, acids, and salts. The vegetable foods indirectly supply the body with a large amount of water, which they absorb in cooking.
112. Proteid Vegetable Foods. The most important proteid vegetable foods are those derived from the grains of cereals and certain leguminous seeds, as peas and beans. The grains when ground make the various flours or meals. They contain a large quantity of starch, a proteid substance peculiar to them called gluten, and mineral salts, especially phosphate of lime. Peas and beans contain a smaller proportion of starch, but more proteid matter, called legumin, or vegetable casein. Of the cereal foods, wheat is that most generally useful. Wheat, and corn and oatmeal form most important articles of diet. Wheat flour has starch, sugar, and gluten—nearly everything to support life except fat.
Oatmeal is rich in proteids. In some countries, as Scotland, it forms an important article of diet, in the form of porridge or oatmeal cakes.
Corn meal is not only rich in nitrogen, but the proportion of fat is also large; hence it is a most important and nutritious article of food. Rice, on the other hand, contains less proteids than any other cereal grain, and is the least nutritious. Where used as a staple article of food, as in India, it is commonly mixed with milk, cheese, or other nutritious substances. Peas and beans, distinguished from all other vegetables by their large amount of proteids—excel in this respect even beef, mutton, and fish. They take the place of meats with those who believe in a vegetable diet.
113. Non-proteid Vegetable Foods. The common potato is the best type of non-proteid vegetable food. When properly cooked it is easily digested and makes an excellent food. It contains about 75 per cent of water, about 20 per cent of carbohydrates, chiefly starch, 2 per cent of proteids, and a little fat and saline matters. But being deficient in flesh-forming materials, it is unfit for an exclusive food, but is best used with milk, meat, and other foods richer in proteid substances. Sweet potatoes, of late years extensively used as food, are rich in starch and sugar. Arrowroot, sago, tapioca, and similar foods are nutritious, and easily digested, and with milk furnish excellent articles of diet, especially for invalids and children.
Explanation of the Graphic Chart. The graphic chart, on the next page, presents in a succinct and easily understood form the composition of food materials as they are bought in the market, including the edible and non-edible portions. It has been condensed from Dr. W. O. Atwater’s valuable monograph on “Foods and Diet.” This work is known as the Yearbook of the U.S. Department of Agriculture for 1894.
KEY: 1, percentage of nutrients; 2, fuel value of 1 pound in calories. The unit of heat, called a calorie, or gramme-degree, is the amount of heat which is necessary to raise one gramme (15.43 grains) of water one degree centigrade (1.8° Fahr.). A, round beef; B, sirloin beef; C, rib beef; D, leg of mutton; E, spare rib of pork; F, salt pork; G, smoked ham; H, fresh codfish; I, oysters; J, milk; K, butter; L, cheese; M, eggs; N, wheat bread; O, corn meal; P, oatmeal; Q, dried beans; R, rice; S, potatoes; T, sugar.
This table, among other things, shows that the flesh of fish contains more water than that of warm-blooded animals. It may also be seen that animal foods contain the most water; and vegetable foods, except potatoes, the most nutrients. Proteids and fats exist only in small proportions in most vegetables, except beans and oatmeal. Vegetable foods are rich in carbohydrates while meats contain none. The fatter the meat the less the amount of water. Thus very lean meat may be almost four-fifths water, and fat pork almost one-tenth water.
COMPOSITION OF FOOD MATERIALS
Nutritive ingredients, refuse, and fuel value.
Fig. 45.—Graphic Chart of the Composition of Food Materials.
114. Non-proteid Animal Foods. Butter is one of the most digestible of animal fats, agreeable and delicate in flavor, and is on this account much used as a wholesome food. Various substitutes have recently come into use. These are all made from animal fat, chiefly that of beef, and are known as butterine, oleomargarine, and by other trade names. These preparations, if properly made, are wholesome, and may be useful substitutes for butter, from which they differ but little in composition.
115. Garden Vegetables. Various green, fresh, and succulent vegetables form an essential part of our diet. They are of importance not so much on account of their nutritious elements, which are usually small, as for the salts they supply, especially the salts of potash. It is a well-known fact that the continued use of a diet from which fresh vegetables are excluded leads to a disease known as scurvy. They are also used for the agreeable flavor possessed by many, and the pleasant variety and relish they give to the food. The undigested residue left by all green vegetables affords a useful stimulus to intestinal contraction, and tends to promote the regular action of the bowels.
116. Fruits. A great variety of fruits, both fresh and dry, is used as food, or as luxuries. They are of little nutritive value, containing, as they do, much water and only a small amount of proteid, but are of use chiefly for the sugar, vegetable acids, and salts they contain.
In moderate quantity, fruits are a useful addition to our regular diet. They are cooling and refreshing, of agreeable flavor, and tend to prevent constipation. Their flavor and juiciness serve to stimulate a weak appetite and to give variety to an otherwise heavy diet. If eaten in excess, especially in an unripe or an overripe state, fruits may occasion a disturbance of the stomach and bowels, often of a severe form.
117. Condiments. The refinements of cookery as well as the craving of the appetite, demand many articles which cannot be classed strictly as foods. They are called condiments, and as such may be used in moderation. They give flavor and relish to food, excite appetite and promote digestion. Condiments increase the pleasure of eating, and by their stimulating properties promote secretions of the digestive fluids and excite the muscular contractions of the alimentary canal.
The well-known condiments are salt, vinegar, pepper, ginger, nutmeg, cloves, and various substances containing ethereal oils and aromatics. Their excessive use is calculated to excite irritation and disorder of the digestive organs.
118. Salt The most important and extensively used of the condiments is common salt. It exists in all ordinary articles of diet, but in quantities not sufficient to meet the wants of the bodily tissues. Hence it is added to many articles of food. It improves their flavor, promotes certain digestive secretions, and meets the nutritive demands of the body. The use of salt seems based upon an instinctive demand of the system for something necessary for the full performance of its functions. Food without salt, however nutritious in other respects, is taken with reluctance and digested with difficulty.
Salt has always played an important and picturesque part in the history of dietetics. Reference to its worth and necessity abounds in sacred and profane history. In ancient times, salt was the first thing placed on the table and the last removed. The place at the long table, above or below the salt, indicated rank. It was everywhere the emblem of hospitality. In parts of Africa it is so scarce that it is worth its weight in gold, and is actually used as money. Torture was inflicted upon prisoners of state in olden times by limiting the food to water and bread, without salt. So intense may this craving for salt become, that men have often risked their liberty and even their lives to obtain it.
119. Water. The most important natural beverage is pure water; in fact it is the only one required. Man has, however, from the earliest times preferred and daily used a variety of artificial drinks, among which are tea, coffee, and cocoa.
All beverages except certain strong alcoholic liquors, consist almost entirely of water. It is a large element of solid foods, and our bodies are made up to a great extent of water. Everything taken into the circulating fluids of the body, or eliminated from them, is done through the agency of water. As a solvent it is indispensable in all the activities of the body.
It has been estimated that an average-sized adult loses by means of the lungs, skin, and kidneys about eighty ounces of water every twenty-four hours. To restore this loss about four pints must be taken daily. About one pint of this is obtained from the food we eat, the remaining three pints being taken as drink. One of the best ways of supplying water to the body is by drinking it in its pure state, when its solvent properties can be completely utilized. The amount of water consumed depends largely upon the amount of work performed by the body, and upon the temperature.
Being one of the essential elements of the body, it is highly important that water should be free from harmful impurities. If it contain the germs of disease, sickness may follow its use. Without doubt the most important factor in the spread of disease is, with the exception of impure air, impure water. The chief agent in the spread of typhoid fever is impure water. So with cholera, the evidence is overwhelming that filthy water is an all-powerful agent in the spread of this terrible disease.
120. Tea, Coffee, and Cocoa. The active principle of tea is called theine; that of coffee, caffeine, and of cocoa, theobromine. They also contain an aromatic, volatile oil, to which they owe their distinctive flavor. Tea and coffee also contain an astringent called tannin, which gives the peculiar bitter taste to the infusions when steeped too long. In cocoa, the fat known as cocoa butter amounts to fifty per cent.
121. Tea. It has been estimated that one-half of the human race now use tea, either habitually or occasionally. Its use is a prolific source of indigestion, palpitation of the heart, persistent wakefulness, and of other disorders. When used at all it should be only in moderation. Persons who cannot use it without feeling its hurtful effects, should leave it alone. It should not be taken on an empty stomach, nor sipped after every mouthful of food.
122. Coffee. Coffee often disturbs the rhythm of the heart and causes palpitation. Taken at night, coffee often causes wakefulness. This effect is so well known that it is often employed to prevent sleep. Immoderate use of strong coffee may produce other toxic effects, such as muscular tremors, nervous anxiety, sick-headache, palpitation, and various uncomfortable feelings in the cardiac region. Some persons cannot drink even a small amount of tea or coffee without these unpleasant effects. These favorite beverages are unsuitable for young people.
123. Cocoa. The beverage known as cocoa comes from the seeds of the cocoa-tree, which are roasted like the coffee berries to develop the aroma. Chocolate is manufactured cocoa,—sugar and flavors being added to the prepared seeds. Chocolate is a convenient and palatable form of highly nutritious food. For those with whom tea and coffee disagree, it may be an agreeable beverage. The large quantity of fat which it contains, however, often causes it to be somewhat indigestible.
124. Alcoholic Beverages. There is a class of liquids which are certainly not properly food or drink, but being so commonly used as beverages, they seem to require special notice in this chapter. In view of the great variety of alcoholic beverages, the prevalence of their use, and the very remarkable deleterious effects they produce upon the bodily organism, they imperatively demand our most careful attention, both from a physiological and an hygienic point of view.
125. Nature of Alcohol. The ceaseless action of minute forms of plant life, in bringing about the decomposition of the elaborated products of organized plant or animal structures, will be described in more detail (secs. 394-398).
All such work of vegetable organisms, whether going on in the moulding cheese, in the souring of milk, in putrefying meat, in rotting fruit, or in decomposing fruit juice, is essentially one of fermentation, caused by these minute forms of plant life. There are many kinds of fermentation, each with its own special form of minute plant life or micro-organism.
In this section we are more especially concerned about that fermentation which results from the decomposition of sweet fruit, plant, or other vegetable, juices which are composed largely of water containing sugar and flavoring matters.
This special form of fermentation is known as alcoholic or vinous fermentation, and the micro-organisms that cause it are familiarly termed alcoholic ferments. The botanist classes them as Saccharomycetes, of which there are several varieties. Germs of Saccharomycetes are found on the surfaces and stems of fruit as it is ripening. While the fruit remains whole these germs have no power to invade the juice, and even when the skins are broken the conditions are less favorable for their work than for that of the moulds,[[18]] which are the cause of the rotting of fruit.
But when fruit is crushed and its juice pressed out, the Saccharomycetes are carried into it where they cannot get the oxygen they need from the air. They are then able to obtain oxygen by taking it from the sugar of the juice. By so doing they cause a breaking up of the sugar and a rearrangement of its elements. Two new substances are formed in this decomposition of sugar, viz., carbon dioxid, which arises from the liquid in tiny bubbles, and alcohol, a poison which remains in the fermenting fluid.
Now we must remember that fermentation entirely changes the nature of the substance fermented. For all forms of decomposition this one law holds good. Before alcoholic fermentation, the fruit juice was wholesome and beneficial; after fermentation, it becomes, by the action of the minute germs, a poisonous liquid known as alcohol, and which forms an essential part of all intoxicating beverages.
Taking advantage of this great law of fermentation which dominates the realm of nature, man has devised means to manufacture various alcoholic beverages from a great variety of plant structures, as ripe grapes, pears, apples, and other fruits, cane juices, corn, the malt of barley, rye, wheat, and other cereals.
The process differs according to the substance used and the manner in which it is treated, but the ultimate outcome is always the same, viz., the manufacture of a beverage containing a greater or less proportion of alcoholic poison. By the process of distillation, new and stronger liquor is made. Beverages thus distilled are known as ardent spirits. Brandy is distilled from wine, rum from fermented molasses, and commercial alcohol mostly from whiskey.
The poisonous element in all forms of intoxicating drinks, and the one so fraught with danger to the bodily tissues, is the alcohol they contain. The proportion of the alcoholic ingredient varies, being about 50 per cent in brandy, whiskey, and rum, about 20 to 15 per cent in wines, down to 5 per cent, or less, in the various beers and cider; but whether the proportion of alcohol be more or less, the same element of danger is always present.
126. Effects of Alcoholic Beverages upon the Human System. One of the most common alcoholic beverages is wine, made from the juice of grapes. As the juice flows from the crushed fruit the ferments are washed from the skins and stems into the vat. Here they bud and multiply rapidly, producing alcohol. In a few hours the juice that was sweet and wholesome while in the grape is changed to a poisonous liquid, capable of injuring whoever drinks it. One of the gravest dangers of wine-drinking is the power which the alcohol in it has to create a thirst which demands more alcohol. The spread of alcoholism in wine-making countries is an illustration of this fact.
Another alcoholic beverage, common in apple-growing districts, is cider. Until the microscope revealed the ferment germ on the “bloom” of the apple-skin, very little was known of the changes produced in cider during the mysterious process of “working.” Now, when we see the bubbles of gas in the glass of cider we know what has produced them, and we know too that a poison which we do not see is there also in corresponding amounts. We have learned, too, to trace the wrecked hopes of many a farmer’s family to the alcohol in the cider which he provided so freely, supposing it harmless.
Beer and other malt liquors are made from grain. By sprouting the grain, which changes its starch to sugar, and then dissolving out the sugar with water, a sweet liquid is obtained which is fermented with yeast, one kind of alcoholic ferment. Some kinds of beer contain only a small percentage of alcohol, but these are usually drunk in proportionately large amounts. The life insurance company finds the beer drinker a precarious risk; the surgeon finds him an unpromising subject; the criminal court finds him conspicuous in its proceedings. The united testimony from all these sources is that beer is demoralizing, mentally, morally, and physically.
127. Cooking. The process through which nearly all food used by civilized man has to pass before it is eaten is known as cooking. Very few articles indeed are consumed in their natural state, the exceptions being eggs, milk, oysters, fruit and a few vegetables. Man is the only animal that cooks his food. Although there are savage races that have no knowledge of cooking, civilized man invariably cooks most of his food. It seems to be true that as nations advance in civilization they make a proportionate advance in the art of cooking.
Cooking answers most important purposes in connection with our food, especially from its influence upon health. It enables food to be more readily chewed, and more easily digested. Thus, a piece of meat when raw is tough and tenacious, but if cooked the fibers lose much of their toughness, while the connective tissues are changed into a soft and jelly-like mass. Besides, the meat is much more readily masticated and acted upon by the digestive fluids. So cooking makes vegetables and grains softer, loosens their structure, and enables the digestive juices readily to penetrate their substance.
Cooking also improves or develops flavors in food, especially in animal foods, and thus makes them attractive and pleasant to the palate. The appearance of uncooked meat, for example, is repulsive to our taste, but by the process of cooking, agreeable flavors are developed which stimulate the appetite and the flow of digestive fluids.
Another important use of cooking is that it kills any minute parasites or germs in the raw food. The safeguard of cooking thus effectually removes some important causes of disease. The warmth that cooking imparts to food is a matter of no slight importance; for warm food is more readily digested, and therefore nourishes the body more quickly.
The art of cooking plays a very important part in the matter of health, and thus of comfort and happiness. Badly cooked and ill-assorted foods are often the cause of serious disorders. Mere cooking is not enough, but good cooking is essential.