ch_pic2FOOD ELEMENTSandSIMPLICITY of DIET
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byE. H. RISLEY, M.D.Chair of Chemistry, College of Medical Evangelists,Loma Linda, California
"Food is any substance that, being taken into the body of animal or plant, serves, through organic action, to build up normal structure or supply waste of tissue."
Food principles or elements are commonly grouped into the following classes:
A brief discussion of these food elements will help our readers to select their food supply more intelligently.
Proteins
The first class of food substances mentioned above are of very great importance to the body. The term "protein" really means, "of first importance." These compoundsare represented by such foods as the white of egg, lean meat, gluten of wheat, and casein of milk. Chemically, proteins are very complex, more so than any other class of food materials. They have in their structure the chemical elements carbon, hydrogen, oxygen, nitrogen, often sulphur and phosphorus, and, less commonly, iron. The nitrogenous element seems to be the most important, since the others mentioned can be obtained from other classes of food; but as these classes of food cannot take the place of protein, it seems clear that the nitrogen is the important constituent.
Most proteins coagulate on heating. An illustration of this property is the coagulation of the white of an egg when the egg is cooked. The proteins all undergo decomposition quite easily. This is evidenced by the ease with which eggs and meat spoil.
Protein molecules are made up of smaller molecules called amino acids. These are the "building stones" from which the working tissues of the body are formed. There are on the average about fifteen different kinds of these amino acids in the proteins, which are especially valuable in supplying building material for the tissues of the human body. These amino acids are united in long chains to form the protein molecule, and in this respect can be compared to cars in a train. By the work of digestion, the proteins are broken down into these comparatively simple building stones, which, when absorbed into the circulation, are used by the body in building working tissues as they are needed.
There are a number of classes of proteins; but since the classification is rather complicated, it will not be given here. To group the various foods as to their relative amounts of protein is often of interest. For example, foods very rich in protein, such as the gluten preparations, lean beef, and white of egg, may be regarded asthe first class; a second class might be formed of those which are moderately high in protein, such as peas, beans, lentils, and walnuts; a third class having a moderate amount of protein, represented by the cereals and breads; and still a fourth class very low in protein, such as vegetables and fruits.
Protein is the tissue builder of the body; but the actual amount of tissue built new each day is very small, therefore the need for a large supply of protein for this purpose is not apparent. Protein not only supplies tissue-building material, but it can also supply heat and energy in a manner similar to the other classes of food elements, carbohydrate and fat, one ounce of the protein yielding one hundred sixteen calories of energy. The excess taken in may be used in this way, as there is no storage of this material in the body. However, to use this kind of fuel takes more work on the part of the body as a whole, as the nitrogenous wastes must be eliminated by the kidneys.
One can see, then, that a certain amount of protein is needed to keep the tissues in good repair, but that it is better to get most of the heat and energy from the food elements specially designed for that purpose; that is, carbohydrate and fat.
The Chittenden standard of diet gives ten per cent of the total fuel value in the form of protein. On the basis of two thousand five hundred total calories a day, two hundred fifty calories of protein would be required. This is equal to two and one seventh ounces actual dry protein. This amount is thought by some to be low, but experimental evidence seems clearly to prove its adequacy in keeping up nutrition.
Fats
The second group of food elements in our classification are substances having a greasy feeling and taste. Theyare lighter than water, leave a grease spot upon paper, are insoluble in water, and soluble in such chemicals as gasoline and ether.
Fats have in their molecules the chemical elements carbon, hydrogen, and oxygen. These elements are put together into two groups, or compounds, glycerin and fatty acids, which, when chemically united, form a fat. When fats are exposed to the open air, and thus contaminated with bacteria, they are likely to become rancid; that is, some of the glycerin and fatty acids are set free from each other. If butter is the fat so decomposed, it becomes very disagreeable, on account of the volatile butyric acid that is set free.
Fatty bodies are usually grouped under a general heading called lipins, but the consideration of the other classes is not essential in this study.
The vegetable kingdom offers a large list of products containing fats, many of which are suitable for food. Following are a few examples, with the percentage of fat in each case: coconuts, sixty-eight per cent; olives, fifty-six per cent; peanuts, forty-one per cent; cotton seed, twenty per cent; oatmeal, six per cent; corn, four per cent.
The animal kingdom is also rich in fat products, illustrated by the following substances used as foods: butter, eighty-five per cent; bacon, sixty-five per cent; cheese, thirty per cent; eggs, eleven per cent; cow's milk, four per cent.
The function of fat in the body is to yield heat and energy primarily. Each ounce of fat yields two hundred sixty-four calories of heat, making the group two and one fourth times as active as either protein or carbohydrate in this respect.
Fats ordinarily supply from twenty-five to thirty per cent of the total calories of a well balanced dietary. On the basis of two thousand five hundred total calories aday, about seven hundred fifty should be fat. At two hundred sixty-four calories to an ounce, we have about three ounces as our daily need of this food element.
Fats are also stored in the body as a reserve of energy. Every one has more or less of this sort of reserve, unless he has been starving for some time, or is suffering from a wasting disease. This reserve of fat also acts as a protection, and gives shape and symmetry to the body.
Recently methods have been devised for changing the unstable vegetable oils into stable, lardlike, solid fats. This process is called hydrogenation, so named because the process is really one of adding hydrogen until the fat becomes saturated and less likely to undergo decomposition into fatty acid and glycerin. The fats thus formed seem to be equal to the animal fats so far as digestion and utilization are concerned, and hence are of considerable economic value at the present time.
Certain fats, including those of butter and milk, are rich in the so-called vitamines, and have been shown, by recent experiments upon animals, to be efficient growth stimulants.
Carbohydrates
The carbohydrates are made up of the chemical elements carbon, hydrogen, and oxygen. By noticing the name, one readily sees that the first part stands for the carbon. The latter half, "hydrate," indicates that water might be present; and in fact, nearly all of these bodies have hydrogen and oxygen present in the proportion to form water, that is, two parts hydrogen to one of oxygen. Carbohydrates ordinarily make up about sixty to sixty-five per cent of the total number of calories of our diet. Most carbohydrates, when pure, are either white powders or white crystalline solids. Many of them are sweet to the taste. The starches and the celluloses are not soluble in cold water, but the sugars are readily soluble.
The classification of the carbohydrates is comparatively simple; and part of it is given here, as it will help in our discussion of the properties of the group:
Celluloseis the coarse woody fiber found in the stems of all plants and in the outer coating of the various grains. Unless cellulose is very young and tender, it is not digested by the human digestive system. However, some forms of it are of value, as they give bulk to the food residue in the digestive tract, and thus stimulate the activity of the intestinal muscle. In this way, cellulose acts as a natural laxative, and in some cases is a very desirable substance to have in the food eaten. The bran of wheat and other cereals is an especially valuable form to use.
Starchis found in all cereals, in many vegetables, in some fruits, and in nuts. It occurs in these different foods in the form of a white, granular substance. The granules have characteristic forms for the different grains, fruits, etc., which can be recognized by the aid of the microscope. Raw starch is insoluble in cold water; hence to be most readily digested, it should be cooked. The cooking process ruptures the granules, and makes the starch itself partially soluble; and in this form, it is more easily attacked by the digestive juices.
Dextrinis formed by heating starch to about 350° F., as in an oven. This degree of heat changes the starch chemically to dextrin. In this dextrin form, it is soluble, and is in reality one step along in the process of digestion.
TABLE A—CEREALS AND LEGUMES
TABLE B—FRUITS
TABLE C—NUTS
TABLE D—VEGETABLES
TABLE E—MISCELLANEOUS FOODS
Thoroughly toasted bread is quite well dextrinized. It is more easily digested, has a sweeter taste than ordinary bread, and in some cases, is more desirable.
Sugar Group
Cane sugaris probably the most important member of the sugar groups. It is obtained from the sugar cane and the sugar beet, the two forms being identical chemically. It can be obtained in a high state of purity, often up to ninety-nine and eight tenths per cent. The English-speaking races use the largest amount of this sugar, in some countries averaging as high as eighty-five pounds per capita a year. Cane sugar is white, crystalline, soluble in water, and has a very sweet taste.
Malt sugaris obtained from grains, such as barley or wheat, by allowing them to sprout. During the sprouting process, there is developed in the grain a ferment that is capable of changing starch to malt sugar. After the malt diastase, as the ferment is called, has had a chance to convert the starch to malt sugar, the sugar is extracted with water, and the resulting solution evaporated to a sirup. This sirup can be evaporated further and the malt sugar or maltose taken out as a solid; but it is usually used in the form of a sirup. This maltose is a natural product to the body, as it is formed by the saliva and the pancreatic juice when they act upon starch.
Milk sugaris found to the extent of about five per cent in cow's milk. It is obtained as a by-product in the manufacture of cheese. The whey, or watery fluid left after the removal of the curd, is evaporated and purified until a fine, white, rather gritty powder, or in some cases a crystalline solid, is obtained. This milk sugar, or lactose, is soluble in water, and has a fairly sweet taste. Lactose is one of the essential food elements for the normal growth of a child or a young animal.Hence one can see why children cannot be reared easily without milk.
Glucoseis the most important sugar in the third group of carbohydrates as given above. It is found naturally in many fruits, and is here called grape sugar. It is the normal sugar of human blood, and in this connection, is usually called dextrose. Glucose is made commercially by boiling starch, most frequently cornstarch, in water, to which sulphuric acid has been added up to one to one and one half per cent. After sufficient boiling, the acid is neutralized with lime, and the sugar separated by chemical methods. If the process is carried out carefully, and reasonably pure reagents are used in the process, the result will be a sirup of fair purity and one of value as a food. Impure and poorly made samples of glucose have given this otherwise wholesome sugar a bad name.
Glucose can also be obtained in solid form by continuing the process of purification a few steps beyond the sirup stage. But let it not be forgotten that any of the sugars, taken in large amounts, may overload the digestive system and the liver, and hence they should be used in reasonable amounts.
Levulose, called also fruit sugar, is found in some of the sweet fruits and in bees' honey. The chief sugar of honey is called invert sugar, and is really made up of equal parts of dextrose and levulose. It is present up to seventy-five per cent in good samples of honey. These sugars, properly used, are excellent foods.
Importance of Carbohydrates
The carbohydrates are our chief source of heat and energy, and as previously stated, furnish sixty to sixty-five per cent of the total fuel value of our food. Each ounce of pure carbohydrate yields one hundred sixteencalories of heat when burned. In caloric yield, they are equal to the proteins gram for gram, but yield less than one half that of the fats. If two thousand five hundred calories are again taken as our standard, then sixty per cent would make one thousand five hundred calories to be furnished by the carbohydrates. At one hundred sixteen calories an ounce, we find that it would require thirteen ounces of pure carbohydrate a day to balance this part of our diet.
Other Essential Elements
The inorganic salts or ash of food are just as essential to the body as the other groups of food elements. These essential salts consist of the most common chemical elements, such as soda, potash, lime, magnesia, iron, phosphorus, sulphur, etc. One might expect to find some rare elements in a piece of mechanism as complicated as the human body, but such is not the case. The body salts are of the most common kinds. These salts are found in proper amounts in foods as produced by nature. We cannot take these salts as they are found in the chemical laboratory and use them to good advantage, but we should make sure that we are taking foods that will supply them in the proper amounts. Our best sources of supply are the grains, the fruits, and the vegetables. It is interesting to note that these mineral elements are generally found most abundantly, in the grains at least, in or near the outer coating, and that our high-grade flours are partially robbed of them when the bran and the middlings are removed. The same seems to be true of potatoes. In peeling, a large part of these salts is removed, and thus the real value of this splendid food product is lessened. This is one of the strong arguments for the use of whole wheat flours and other whole grain products. These inorganic salts are needed in the body to keep thevarious tissues up to their normal in composition. For example, the blood constantly needs some iron to build the red cells. Though the actual amount needed is very small, yet that small amount is exceedingly important to have at hand.
As some of these salts are constantly being eliminated from the body, there must be a constant supply to keep the tissues in equilibrium.
Vitamines
Vitamines are elsewhere considered in this booklet, hence only a very brief summary here. The chemistry of these products is very little understood at present. They were so named by Funk because of their nitrogen content and similarity to ammonia, the name really meaningvital ammonias. The term "vital" carries with it the idea of their importance to life. Some persons have questioned this name; but up to the present, it seems to be the best suggested.
The importance of the vitamines in nutrition has been very clearly demonstrated in experiments upon animals, and these experiments have been repeated a sufficient number of times to be conclusive. Animals have been fed upon pure protein, fat, carbohydrate, and salts, but with vitamine removed or destroyed; and although receiving calories enough, they fail to keep up their nutrition. With a simple change of dietary to include a small amount of food containing the vitamine, without any change in the total calories eaten, their nutrition improves quickly, and they come back to a normal state.
Foods rich in vitamine are represented by milk, fresh vegetables, fresh fruits, and whole grain products. Foods poor in these substances are represented by sterilized and preserved milks, dried fruits, dried vegetables, white flour, and polished rice.
Vitamines are reduced or lost by the following processes in the preparation of foods: taking off the coating of grain, overheating, washing out in cooking, and drying.
Importance of Water
Water, although not a food in the sense of yielding fuel value to the body, is a most important agent in all the various chemical processes taking place in the tissues.
Water is the universal solvent; and because of this property, it carries both food and waste to and from the tissues. The average person needs from three to five quarts a day, a part of which is taken as a portion of the food eaten. This leaves from three to five pints to be taken as a drink. Good drinking water should be colorless, odorless, and of an agreeable taste; should be free from organic matter, poisonous metals, and the bacteria of disease; and should be low in nonpoisonous mineral salts—that is, should be reasonably soft.
There are three common classes of water that are used for drinking purposes; namely, rain water, surface water, and ground water. Rain water is the purest if properly collected. Surface water—water from lakes, streams, etc.—is most likely to be contaminated with organic matter and bacteria. Ground water—that is, water from springs and wells—is likely to be the hardest, but is usually free from bacteria of disease unless there is some contamination from the surface. To take a fairly good quantity of water between meals is better than to drink too freely at the meal hour.
Great care should be taken in selecting the supply of drinking water, as when contaminated, it is a very fruitful means for the transmission of diseases, particularly such diseases as typhoid fever. If not certain of the purity of a water supply, one can be sure to destroy allthe disease-producing bacteria by boiling the water for a few minutes, then cooling, and drinking as usual.
Simple Dietetic Principles
1. Food should be pleasant to the sight and the taste.2. Eat slowly. Masticate thoroughly.3. Do not wash down your food with water or any kind of beverage.4. Cheerfulness is an important aid to digestion. The mind should be free from care, and the surroundings pleasant.5. Avoid overeating.6. There should be between five and six hours' interval between meals, and no food should be taken during this interval.7. Make your list of foods balance up with about ten per cent protein, twenty-five to thirty per cent fat, and sixty to sixty-five per cent carbohydrate.8. Eat few kinds of food at a meal, but vary the menu from day to day.9. Food should be properly cooked to get the best results.10. Do not eat late at night. The evening meal should be the lightest.11. Eat green vegetables frequently in season.12. Fresh fruits are very helpful in the diet.13. Combine fruits, grains, and nuts.14. Fruits and coarse vegetables are not a good combination.15. It is better not to take large quantities of cane sugar and milk together.16. Do not eat rich and complicated mixtures of food.17. Flesh meats are expensive, they make the protein high, and are second-hand foods. Their place may easilybe supplied by other foods.18. Avoid excessive amounts of salt.19. Do not use pepper or other irritating condiments and spices in seasoning your food.20. Tea and coffee are not foods, and should be entirely dispensed with.21. Alcohol is a poison, and should be entirely eliminated from the menu.
1. Food should be pleasant to the sight and the taste.
2. Eat slowly. Masticate thoroughly.
3. Do not wash down your food with water or any kind of beverage.
4. Cheerfulness is an important aid to digestion. The mind should be free from care, and the surroundings pleasant.
5. Avoid overeating.
6. There should be between five and six hours' interval between meals, and no food should be taken during this interval.
7. Make your list of foods balance up with about ten per cent protein, twenty-five to thirty per cent fat, and sixty to sixty-five per cent carbohydrate.
8. Eat few kinds of food at a meal, but vary the menu from day to day.
9. Food should be properly cooked to get the best results.
10. Do not eat late at night. The evening meal should be the lightest.
11. Eat green vegetables frequently in season.
12. Fresh fruits are very helpful in the diet.
13. Combine fruits, grains, and nuts.
14. Fruits and coarse vegetables are not a good combination.
15. It is better not to take large quantities of cane sugar and milk together.
16. Do not eat rich and complicated mixtures of food.
17. Flesh meats are expensive, they make the protein high, and are second-hand foods. Their place may easilybe supplied by other foods.
18. Avoid excessive amounts of salt.
19. Do not use pepper or other irritating condiments and spices in seasoning your food.
20. Tea and coffee are not foods, and should be entirely dispensed with.
21. Alcohol is a poison, and should be entirely eliminated from the menu.