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The Relation of Food to the Body.
ОглавлениеIn order to understand the relation of food to the sustenance and repairing of the body, it will be necessary to learn, first, of what the body is composed, and the corresponding elements contained in the food required to build and keep the body in a healthy condition. The following table gives the approximate analysis of a man weighing 148 pounds:—
| Oxygen | 92.1 | pounds. |
| Hydrogen | 14.6 | " |
| Carbon | 31.6 | " |
| Nitrogen | 4.6 | " |
| Phosphorus | 1.4 | " |
| Calcium | 2.8 | " |
| Sulphur | 0.24 | " |
| Chlorine | 0.12 | " |
| Sodium | 0.12 | " |
| Iron | 0.02 | " |
| Potassium | 0.34 | " |
| Magnesium | 0.04 | " |
| Silica | ? | " |
| Fluorine | 0.02 | " |
| ——— | ||
| Total | 148.00 | pounds. |
As food contains all these elements, and as there is constant wearing and repair going on in the body, it will be readily seen how necessary some knowledge of the relation of food to the body is, in order to preserve health.
Hydrogen and oxygen combined form water, hence we find from the above calculation that about three-fifths of the body is composed of water. Carbon is a solid: diamonds are nearly pure carbon; "lead" of lead pencils, anthracite coal and coke are impure forms of carbon. Carbon combined with other elements in the body makes about one-fifth of the whole weight. Carbon with oxygen will burn. In this way the carbon taken into the body as food, when combined with the oxygen of the inhaled air, yields heat to keep the body warm, and force—muscular strength—for work. The carbonic acid (or carbon dioxide) is given out through the lungs and skin. In the further study of carbonaceous foods, their relation to the body as fuel will be more clearly understood, as carbon is the most important fuel element. Phosphorus is a solid. According to the table, about one pound six ounces would be found in a body weighing 148 pounds. United with oxygen, phosphorus forms what is known as phosphoric acid; this, with lime, makes phosphate of lime, in which form it is found in the bones and teeth; it is found also in the brain and nerves, flesh and blood. Hydrogen is a gas, and like carbon unites with the oxygen of the inhaled air in the body, thus serving as fuel. The water produced is given off in the respiration through the lungs and as perspiration through the skin.[3] Calcium is a metal. The table given allows three pounds of calcium; united with oxygen, calcium forms lime. This with phosphoric acid makes phosphate of lime, the basis of the bones and teeth, in which nearly all the calcium of the body is found.
The elements which bear no direct relation to the force production of the body, but which enter into tissue formation, are chlorine, sulphur, iron, sodium, potassium, phosphorus, calcium and magnesium. Bone tissue contains about 50 per cent. of lime phosphate, hence the need of this substance in the food of a growing infant, in order that the bones may become firm and strong. Lack of iron salts in the food impoverishes the coloring matter of the red blood corpuscles on which they depend for their power of carrying oxygen to the tissues; anæmia and other disorders of deficient oxidation result. The lack of sufficient potash salts is a factor in producing scurvy, a condition aggravated by the use of common salt. A diet of salt meat and starches may cause it, with absence of fresh fruit and vegetables. Such illustrations show the need of a well-balanced diet.
In order to understand the value of the various classes of food and their relation to the body as force producers, tissue builders, etc., the following table may prove helpful:—
| Nitrogen. | C.H. Combustibles Calculated as Carbon | |
| Beef, uncooked | 3.00 | 11.00 |
| Roast beef | 3.53 | 17.76 |
| Calf's liver | 3.09 | 15.68 |
| Foie-gras | 2.12 | 65.58 |
| Sheep's kidneys | 2.66 | 12.13 |
| Skate | 3.83 | 12.25 |
| Cod, salted | 5.02 | 16.00 |
| Herring, salted | 3.11 | 23.00 |
| Herring, fresh | 1.83 | 21.00 |
| Whiting | 2.41 | 9.00 |
| Mackerel | 3.74 | 19.26 |
| Sole | 1.91 | 12.25 |
| Salmon | 2.09 | 16.00 |
| Carp | 3.49 | 12.10 |
| Oysters | 2.13 | 7.18 |
| Lobster, uncooked | 2.93 | 10.96 |
| Eggs | 1.90 | 13.50 |
| Milk (cows') | 0.66 | 8.00 |
| Cheese (Brie) | 2.93 | 35.00 |
| Cheese (Gruyere) | 5.00 | 38.00 |
| Cheese (Roquefort) | 4.21 | 44.44 |
| Chocolate | 1.52 | 58.00 |
| Wheat (hard Southern, variable average) | 3.00 | 41.00 |
| Wheat (soft Southern, variable average) | 1.81 | 39.00 |
| Flour, white (Paris) | 1.64 | 38.50 |
| Rye flour | 1.75 | 41.00 |
| Winter barley | 1.90 | 40.00 |
| Maize | 1.70 | 44.00 |
| Buckwheat | 2.20 | 42.50 |
| Rice | 1.80 | 41.00 |
| Oatmeal | 1.95 | 44.00 |
| Bread, white (Paris, 30 per cent. water) | 1.08 | 29.50 |
| Bread, brown (soldiers' rations formerly) | 1.07 | 28.00 |
| Bread, brown (soldiers' rations at present) | 1.20 | 30.00 |
| Bread, from flour of hard wheat | 2.20 | 31.00 |
| Potatoes | 0.33 | 11.00 |
| Beans | 4.50 | 42.00 |
| Lentils, dry | 3.87 | 43.00 |
| Peas, dry | 3.66 | 44.00 |
| Carrots | 0.31 | 5.50 |
| Mushrooms | 0.60 | 4.52 |
| Figs, fresh | 0.41 | 15.50 |
| Figs, dry | 0.92 | 34.00 |
| Coffee (infusion of 100 grams) | 1.10 | 9.00 |
| Tea (infusion of 100 grams) | 1.00 | 10.50 |
| Bacon | 1.29 | 71.14 |
| Butter | 0.64 | 83.00 |
| Olive oil | Trace | 98.00 |
| Beer, strong | 0.05 | 4.50 |
| Wine | 0.15 | 4.00 |
"The hydrogen existing in the compound in excess of what is required to form water with the oxygen present is calculated as carbon. It is only necessary to multiply the nitrogen by 6.5 to obtain the amount of dry proteids in 100 grams of the fresh food substance." (Dujardin-Beauretz.) The following simple rules are given by Parks:—"1st. To obtain the amount of nitrogen in proteid of foods, divide the quantity of food by 6.30. 2nd. To obtain the carbon in fat multiply by 0.79. 3rd. To obtain the carbon in carbohydrate food multiply by 0.444. 4. To obtain the carbon in proteid food multiply by 0.535."
Finding that our food and our bodies contain essentially the same elements, we must also bear in mind that the body cannot create anything for itself, neither material nor energy; all must be supplied by the food we eat, which is transformed into repair material for the body. Therefore, the object of a course of study dealing with the science of this question, as it relates to the daily life, should be to learn something of how food builds the body, repairs the waste, yields heat and energy, and to teach the principles of food economy in its relation to health and income. This, with the development of executive ability, is all that can be attempted in a primary course.
FOOTNOTE:
[3] An illustration of vapor rising may be given by breathing upon a mirror.
