Where Our Foods Come From.We eat a great many different kinds of foods, which come to our tables from all over the world, and hundreds of different animals and plants contribute to our daily meals. It would be fascinating to trace the story of even a single breakfast. The orange perhaps grew in a grove on the sunny shores of Florida. The rice may have been cultivated in Texas. The cream you pour on it probably came from the milk of cows in your own state, and the sugar, from a tall plant in the cane fields of Louisiana. The bread was made from wheat grown in the grain fields of the West; the butter may have been churned from the milk of a cow in Wisconsin; and the eggs were laid perhaps by hens in Kansas.
In other parts of the world men eat things that seem very strange to us, and some people thrive on what appears to be a very limited menu. The Chinaman eats rats and soup made of a sticky bird’s nest. The French epicure enjoys dishes prepared from frogs and snails. The East Indian makes rice the greater part of his diet, while the Eskimo eats great quantities of fat and whale oil. Yet they turn all these curious things into good human muscle and nerve and other tissue.
The Principal Kinds of Foods.Different as these various foods are in appearance, texture, and flavor, they are in reality made up of only a few kinds of substances, which are so important that every one should know about them. They are water, proteins, carbohydrates, fats, and salts.
Almost all foods contain a certain amount of water, though they may seem quite dry and hard. It is not surprising to know that milk is 85 per cent or more water, and an orange 65 per cent water; but it hardly seems possible that in a piece of beefsteak 6o to 70 per cent is water, and in a slice of bread 35 per cent, and that the body itself is about 70 per cent water. Water is constantly being given off from the lungs, the skin, and the kidneys. In order to make good this loss, we ought to drink about three pints, or six glasses, of water a day, besides the water we get in our foods.
Proteins are the food substances which are most abundant in meats and animal foods. Peas, beans, and certain other plant foods also contain a good deal of protein.
The white of egg (egg albumin) is a good example of such a food, being made up almost entirely of protein and water; and lean beef contains little but these two substances.
Carbohydrates (kar’ bo hi’ drats), on the other hand, occur most abundantly in plant foods, such as potatoes and cereals. Boiled potatoes are 20 per cent carbohydrate, and good bread over 50 per cent. Starch and sugar are the two commonest kinds of carbohydrate in our foods.
Fats are found in largest amounts in animal foods. We can often see the fat in various cuts of meat. Eggs contain about 10 per cent of fat, and milk about 4 per cent.
Our foods also contain salts or minerals of many kinds, not only the kind of salt that comes to the table in the salt shaker, but other mineral substances like it. These salts are present only in very small amounts, but the body needs a dozen or more different kinds in order to keep healthy. Lime, for instance, is essential to the building up of the skeleton, and iron and other salts are necessary for other tissues of the body.
People who live on a restricted diet of only a few kinds of foods, particularly cooked foods, may not thrive, even though they have plenty of all the five food elements described above. This has led to the theory that there are peculiar substances, called vitamins (vit’ a mins), in certain foods, which are necessary to the body. In order to supply these elements, the diet should always contain a moderate amount of uncooked foods, such as raw fruits, lettuce, and – tomatoes. Fruits and vegetables are important articles of diet for another reason: because the alkaline products formed from them in digestion neutralize the acid products formed in the digestion of meats, which are harmful to the body when present in excess.
Classification of Common Foods.The Life Extension Institute Manual on How to Live (by Professor Irving Fisher and Dr. E. L. Fisk) gives the following table of some common foods classified in regard to their richness in protein and fat. The foods in the lower left-hand corner of the table, which are poor in both protein and fat, are the richest in carbohydrate.
The Values of Food Substances.As we have already learned, we need foods for at least two general purposes: to build up new body tissue to replace that which is constantly wasting away, and to supply the energy for the various activities of life. The protein foods, especially, supply the first needthe building up and repair of body tissue. Proteins may also furnish energy, but the chief energy-producing foods are the carbohydrates and fats.
A general idea of the energy value of various kinds of food may be obtained by driving off the water they contain (as by drying for a long time in the sun) and then burning them. Heat is a form of energy, and whatever burns has energy, or the power of producing heat. Butter and sugar burn in a hot fire even without previous drying. Bread and meat burn freely after the water has been dried out. On the other hand, vegetables, such as cauliflower or spinach, and fruits dry almost to nothing and burn very feebly. If salt is put on the top of the stove, it does not burn at all, for salt contains no energy, although salts are necessary for the upbuilding and the healthy working of the body.
The energy value of food is measured in units called calories, just as flour is measured in pounds. One calorie of heat energy would warm one kilogram (about two pints) of water one degree Centigrade. One large egg, two medium slices of white bread, an ordinary portion of butter, or one large banana, each contains about 100 calories of food energy. To keep the body in good condition, the average grown person needs 2500 calories a day–or somewhat more, if he has much muscular work to do.
There is a great difference in the amount of energy that can be obtained from different kinds of food at the same cost. For instance, 100 calories in the form of an egg cost ten times as much as 100 calories in the form of flour. It is important that people who buy food, and those who pay for it, should know something about the energy value of different foods, in order that they may get the greatest value for the money spent. The relative amount of energy value to be obtained for ten cents in buying some common foods is shown in Fig. 34. More extensive tables of the caloric value and composition of certain foods are given in the Appendix, on page 372.
How These Facts were Discovered.One way of finding out the food needs of the body is to study the diet that people select and thrive on, when they can choose the foods they want. A more exact way is to keep people or animals in a carefully built, tight room, called a calorimeter chamber. The heat given off from their bodies to the air and the walls is measured; the air, which goes in and out through special pipes, is measured and analyzed; the food eaten is measured and analyzed; and so are all the excretions or discharges from the body. In this way it is possible to measure exactly the calories of energy which the body takes in as food and the calories which it gives off in heat and in work done. This sort of study of the food needs of the body was begun in Munich by a pioneer German physiologist, von Pettenkofer, and is carried on in many laboratories all over the world to-day.
Importance of Variety in Foods.It must be remembered that the energy value of food is not the only thing to be considered. As far as energy alone is concerned, we might obtain our 2500 calories a day by eating about twenty ounces of the white of egg or twenty ounces of sugar or ten ounces of butter. If this were all that were necessary, we could live entirely on such a simple cheap food as bread. Our instincts teach us, however, to eat foods of different kinds, and there is good reason for this.
Certain native peoples in the Philippine Islands and in Japan live largely on rice, which gives plenty of energy but lacks certain important food substances. These people suffer from a peculiar disease called beri beri, which is quickly cured by changing their diet. The sickness called pellagra, which occurs in our Southern states, seems to be closely connected with a diet poor in protein. In olden times, sailors on long voyages used to have a disease called scurvy, which we now know was due simply to the fact that they were fed on salted and cured meats, with no fresh fruits or vegetables. They were starved for one kind of food, though they had enough, and too much, of other kinds. Fruit juices supply the substances needed and quickly clear up any symptoms of scurvy that follow such a one-sided diet. Experience teaches that in order to keep healthy we must have a considerable variety of foods which contain all the kinds of food substance the body needs, in the right proportions.
EXPLANATION OF FIG. 34. The broad band opposite each food material indicates by its length the amount of nutrients (protein, fats, carbohydrates) which can be bought for ten cents. The three vertical lines at the top show the points on this scale which correspond to 1 lb., 2 lb., and 3 lb., respectively.
The narrow, solid black band indicates in the same way the calories of fuel value obtained for ten cents. The three vertical lines at the top correspond to 2000, 4000, and 6000 calories, respectively, when considered in relation to the solid black band.
For example, ten cents worth of fat salt pork furnishes about % lb. of nutrients (mostly fat) and about 3000 calories of fuel value. Ten cents worth of fresh dressed codfish furnishes only about 1/8 lb. of nutrients and about 250 calories. Codfish is almost entirely protein.
A Balanced Diet.Those who are responsible for the feeding of large numbers of people, as in armies, or schools and colleges, and other institutionsmake a scientific study of food values and work out regular diets which combine foods in the right amounts and proportions. Such a diet is known as a balanced diet, because in it the various food substances are so combined that they balance one another properly.
A good example of a balanced diet reduced to small pro-portions for easy transportation is the standard daily field ration of a soldier in the United States army. It contains 12 ounces of bacon, i8 ounces of bread, 2.4 ounces of beans, 20 ounces of potatoes, 1.28 ounces of prunes or preserves, 1.12 ounces of coffee, 3.2 ounces of sugar, 5 ounces of evaporated milk, .i6 gills of vinegar, .64 ounces of salt, .04 ounces of black pepper, .64 ounces of lard, and .5 ounces of butter. Protein is supplied by the bacon, beans, and milk, and in small part by the bread; carbohydrate by the bread, potatoes, sugar, milk, and beans; fat by the bacon, milk, lard, and butter. The prunes and preserves help to supply salts and “balance” the ration.
Excesses of Diet.It is probably more common for people to be made ill by too much of certain kinds of food than by too little. You have perhaps had some experience of your own which has taught you how ill one may be made by eating too much candy or green apples or some other unripe, indigestible fruit.
Many grown people become more or less ill because of overeating, though they may not have a pain, like the boy who eats green apples. They overload their digestive systems and do not know what the matter is when they feel heavy and dull and cross. In such a case, the whole body may be poisoned by the decay of the excess of food in the intestines and by the absorption of poisons formed by the bacteria which are decomposing it.
An excess of protein food is particularly unhealthful, and many people suffer from eating too much meat. Protein should make up about 15 per cent of the calories in the diet.
There are two good rules to remember in connection with this question. One is that meat should generally be eaten only once a day. The other is a more complicated rule suggested by Professor H. C. Sherman of Columbia University, that an ordinary family should, spend about as much for milk, vegetables, and fruits as for meat, fish, and eggs. Talk this rule over with your family at home.
Fads in Diet.A great many people get in the habit of thinking they can eat only certain things, and that other foods “disagree” with them. Sometimes this is true. Now and then we find a person who is really made ill by milk or eggs or strawberries or some other special article of food; in such a case, that food should be avoided. Often, however, the fear of certain foods is only prejudice. Sometimes it is founded on a wrong theory, on an idea that people should live entirely on nuts or fruits or breakfast foods or some other special food. Any such limit on the diet is a mistake. The ordinary healthy person thrives best with foods of different kinds.
If you wish to cultivate habits of eating which will keep you healthy, you should learn to like all wholesome kinds of vegetables and fruits, bread, butter, cereals, and the like. If you form the habit of eating slowly, you will be much less likely to eat too much or to eat the wrong kinds of food.
When to Limit the Diet.–In hot weather the digestive system does not do its work so readily as at other times, and the body does not need so much energy as when it has to produce a great deal of heat. It is always a good plan, therefore, to eat lightly in warm weather.
In illness, too, it is generally well to limit the diet. After a long illness, the body may need a good deal of especially strengthening food. At the beginning of an illness, however, particularly when there is fever or disturbance of the digestion, the food should often be cut down. Loose movements of the bowels, in particular, mean that little or no food should be taken for a time. Skipping a meal is often better than medicine in such a case.
Pure Food.The city, state, and national governments are doing many things to prevent fraud in foods of all kinds and to make sure that only pure food is sold. The national Pure Food Law, which was passed in 1906, requires that foods and drugs shall not be adulterated and forbids any false statements on the labels. It is very important that this law should be enforced, so that people may know just what they are buying and may not be cheated into paying high prices for foods that are mixed with cheaper or less desirable substances.
Clean Food.It is even more important that food should be clean than that it should be pure. Most of the common adulterants of food lower its quality or its food value but do not make it poisonous. If, however, food has been handled by a person with dirty hands, or if flies have crawled over it, it may have become infected with disease germs so as to be poisonous to people who eat it. Not long ago ninety-three people who had attended a church supper in California were taken ill with typhoid fever, because one of the women who cooked the supper was infected with this disease. Every person should make it a rule never to handle food, or to eat, without thoroughly washing the hands; and all food should be carefully-covered and protected from flies and dust.
The Decay of Foods.Another danger to be considered in connection with foods is spoiling or decay. The spoiling of food is always due to germs growing in it. In milk, for example, there are always a few germs; they grow very fast if the milk is in a warm place, and soon spoil or sour it. Sometimes in this spoiling, poisons are formed which make people very ill. All perishable food should be kept cool, so as to check the growth of germs; and one should be very careful not to eat food, particularly fish or meat, that does not smell sweet.
Cooked and Uncooked Foods.Some foods, such as fruits, are eaten raw, and we always need some raw foods in our diet. Most of our foods, however, are cooked, and for good reasons.
In the first place, many foods would be hard to digest without cooking. Starchy foods, like oatmeal or bread or potatoes, are highly indigestible unless the little grains of starch have been broken up by thorough cooking. In the second place, the high temperature used in most processes of cookery kills disease germs, and so makes safe many foods that would otherwise be dangerous. Cooking also makes food pleasant to the taste and thus aids in its digestion.
Methods of Cooking: Cooking is an art of great importance, and girls in particular should take every opportunity of learning how foods may be prepared so as to be healthful and appetizing.
There are four principal methods of cooking: boiling, baking, broiling, and frying. In boiling, the food is cooked in water. In baking or roasting, it is cooked in hot airin an oven or over a hot fire, but not in the flame. In broiling, the food is cooked directly over the fire itself; and in frying, it is cooked in a pan of hot fat.
Boiling is a cheap and easy method of cooking. It must be remembered, however, that in boiling much of the “goodness” of the food will escape into the water. This is, of course, desirable in the case of soups, but it is a wasteful method when we do not eat the liquid in which the food is boiled. If it is desired that the food sub-stances should be extracted, as in making soup from meat, the food should be put on the stove to boil in cold water.
Otherwise, it should be placed at once in boiling water, which has the effect of searing over the surface and keeping in much of the strength. One of the advantages of roasting and broiling over a hot fire is that the extreme heat forms a crust which keeps in the juices.
Frying is one of the least desirable methods of cooking, because fried foods are likely to be soaked with fat, which makes them hard to digest. To obtain the best results in frying, a large quantity of very hot fat should be used. This forms a crust over the food which keeps much of the fat out of it.
A very important aid to the housewife is the fireless cooker, which consists of a metal pail inclosed in a box, with an air space between the pail and the inner surface of the box. This air space is partially filled with paper or similar material. Food is heated thoroughly before it is put into the cooker. Often a hot stone is placed in the bottom of the pail before the food is put in. The covers of the pail and the box are closed tightly to prevent, as far as possible, the escape of heat. The food is then allowed to cook very slowly under the influence of the heat already contained in it and that contributed by the stone. This device saves time and expense for fuel, and keeps much of the food value and flavor that are lost in other methods of cooking.
Diet Accessories and Stimulants. Besides the various foods that are necessary for the body, people take many things with their meals, or between their meals, which are not needed at all as fuel or building materials, but which are eaten or drunk because of their pleasant taste or because of some stimulating effect on the body. Some of these, like soda water and lemonade, are harmless and pleasant when taken in moderation. Drinking soda water or other beverages too often between meals, however, may lessen the appetite for wholesome food and finally do harm.
Tea and coffee are food accessories that are in very general use. Both of them contain tannic acida substance which, when used in excess, may be injurious to the mucous membrane of the stomachand caffeine and other stimulants which act upon the heart and nervous system. There is a great difference in the effect of these drinks upon different individuals, and some people cannot take them at all. They should never be used by children. The word stimulant comes from the Latin name for an ox whip; and whipping up the body to do things is always dangerous.
QUESTIONS FOR DISCUSSION AND REVIEW
1. What different parts of the world supplied your dinner yesterday?
2. Compare the diet of a Mexican and an Eskimo. Why are they so widely different?
3. Name the principal substances of which our food is composed.
4. Name three foods in which each of these food substances is found.
5. What percentage of the human body is water?
6. Why is it well for us to eat a certain amount of uncooked fruit and vegetables?
7. What is the chief value of protein?
8. What are the greatest energy-producing foods?
9. What do we mean by a calorie?
10. What is the right calorie-value of food for the average man per day?
11. Why does a boy of ten need more food than his mother, who is perhaps twice as large?
12. Why does a man who shovels coal need more food than a man who takes tickets?
13. Criticize the following menus:
I. Macaroni with tomatoes and cheese H. Cream of. celery soup
Baked potatoes Roast pork, fried potatoes
White bread and butter Peanut butter and banana salad
Grapefruit salad, with crackers Doughnuts
Rice pudding Hot chocolate
III. Clear beef soup
Hard boiled egg salad, with cheese Baked meringue (white of egg)
14. Make a list of the different foods you ate at one particular meal, and after each food write its chief nutritive value. Can you suggest any improvements in this menu, as regards health?
15,. Why is it well to eat a variety of foods?
16. John was pale, undersized, and weak, The doctor said that he was undernourished. Suggest several possible causes. ’7. What is meant by a balanced diet?
18. What becomes of the excess, if we eat more food than we can digest?
19. Make a set of rules about healthful eating.
20. Under what conditions should we use less food than ordinarily?
21. What does the United States Government do for the protection of foods?
22. Why is a refrigerator or spring-house a necessary part of every household?
23. What are some of the advantages gained by cooking foods?
24. Give an example of each of the four principal methods of cooking.
25. Which are more easily digestedbaked or fried potatoes?
26. Why should doughnuts or crullers be fried in very hot, deep fat?
27. Should we drink water with our meals? Give your reason for your opinion.
28. What effect does the drinking of tea and coffee have upon. the human body? Compare the effects of these beverages on grown people and on children.
29. What is the best beverage for boys and girls?